TRAMP 2.6.3 User Manual
This file documents TRAMP 2.6.3, a remote file editing package for Emacs.
TRAMP stands for “Transparent Remote (file) Access, Multiple
Protocol”. This package provides an easy, convenient, and consistent
interface to editing remote files transparently, just as if they are
local files. This extends to editing, version control, dired
,
and more.
You can find the latest version of this document on the web at https://www.gnu.org/software/tramp/.
The latest release of TRAMP is available for download, or you may see Obtaining TRAMP for more details, including the Git server details.
TRAMP also has a Savannah Project Page.
There is a mailing list for TRAMP, available at tramp-devel@gnu.org, and archived at the TRAMP Mail Archive.
Copyright © 1999–2024 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover Texts being “A GNU Manual”, and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled “GNU Free Documentation License”.
(a) The FSF’s Back-Cover Text is: “You have the freedom to copy and modify this GNU manual.”
Table of Contents
- 1 An overview of TRAMP
- 2 Obtaining TRAMP
- 3 Short introduction how to use TRAMP
- 4 Configuring TRAMP
- 4.1 Types of connections to remote hosts
- 4.2 Inline methods
- 4.3 External methods
- 4.4 GVFS-based external methods
- 4.5 FUSE-based external methods
- 4.6 Selecting a default method
- 4.7 Selecting a default user
- 4.8 Selecting a default host
- 4.9 Connecting to a remote host using multiple hops
- 4.10 Passing firewalls
- 4.11 Using Non-Standard Methods
- 4.12 Selecting config files for user/host name completion
- 4.13 Reusing passwords for several connections
- 4.14 Reusing connection related information
- 4.15 Setting own connection related information
- 4.16 How TRAMP finds and uses programs on the remote host
- 4.17 Remote shell setup hints
- 4.18 Ssh setup hints
- 4.19 FUSE setup hints
- 4.20 Android shell setup hints
- 4.21 Auto-save, File Lock and Backup configuration
- 4.22 Protect remote files by encryption
- 5 Using TRAMP
- 5.1 TRAMP file name conventions
- 5.2 Alternative file name syntax
- 5.3 File name completion
- 5.4 Declaring multiple hops in the file name
- 5.5 Expanding ~ to home directory
- 5.6 Integration with other Emacs packages
- 5.6.1 Running remote programs that create local X11 windows
- 5.6.2 Running
shell
on a remote host - 5.6.3 Running
shell-command
on a remote host - 5.6.4 Running
eshell
on a remote host - 5.6.5 Running a debugger on a remote host
- 5.6.6 Running remote processes on MS Windows hosts
- 5.6.7 Remote process connection type
- 5.6.8 Process properties of asynchronous remote processes
- 5.6.9 Improving performance of asynchronous remote processes
- 5.7 Cleanup remote connections
- 5.8 Renaming remote files
- 5.9 Archive file names
- 6 Reporting Bugs and Problems
- 7 Frequently Asked Questions
- 8 How file names, directories and localnames are mangled and managed
- 9 How to Customize Traces
- Appendix A GNU Free Documentation License
- Function Index
- Variable Index
- Concept Index
Next: Obtaining TRAMP, Up: TRAMP 2.6.3 User Manual [Contents][Index]
1 An overview of TRAMP
TRAMP is for transparently accessing remote files from within
Emacs. TRAMP enables an easy, convenient, and consistent
interface to remote files as if they are local files. TRAMP’s
transparency extends to editing, version control, and dired
.
TRAMP can access remote hosts using any number of access
methods, such as ssh
, scp
, telnet
, and
related programs. If these programs can successfully pass
ASCII characters, TRAMP can use them. TRAMP
does not require or mandate 8-bit clean connections.
TRAMP’s most common access method is through ssh
, a
more secure alternative to ftp
and other older access
methods.
TRAMP on MS Windows operating systems is integrated with the
PuTTY package, and uses the plink
program.
TRAMP mostly operates transparently in the background using the connection programs. As long as these programs enable remote login and can use the terminal, TRAMP can adapt them for seamless and transparent access.
TRAMP temporarily transfers a remote file’s contents to the local host editing and related operations. TRAMP can also transfer files between hosts using standard Emacs interfaces, a benefit of direct integration of TRAMP in Emacs.
TRAMP can transfer files using any number of available host
programs for remote files, such as rcp
, scp
,
rsync
or (under MS Windows) pscp
. TRAMP
provides easy ways to specify these programs and customize them to
specific files, hosts, or access methods.
For faster small-size file transfers, TRAMP supports encoded
transfers directly through the shell using mimencode
or
uuencode
provided such tools are available on the remote
host.
TRAMP behind the scenes
Accessing a remote file through TRAMP entails a series of actions, many of which are transparent to the user. Yet some actions may require user response (such as entering passwords or completing file names). One typical scenario, opening a file on a remote host, is presented here to illustrate the steps involved:
C-x C-f to initiate find-file, enter part of the TRAMP file name, then hit TAB for completion. If this is the first time connecting to that host, here’s what happens:
- TRAMP invokes ‘telnet host’ or ‘ssh -l user host’ and establishes an external process to connect to the remote host. TRAMP communicates with the process through an Emacs buffer, which also shows output from the remote host.
- The remote host may prompt for a login name (for
telnet
, for example) in the buffer. If on the other hand, the login name was included in the file name portion, TRAMP sends the login name followed by a newline. - The remote host may then prompt for a password or passphrase (for
ssh
or fortelnet
). TRAMP displays the password prompt in the minibuffer. TRAMP then sends whatever is entered to the remote host, followed by a newline. - TRAMP now waits for either the shell prompt or a failed login
message.
If TRAMP does not receive any messages within a timeout period (a minute, for example), then TRAMP responds with an error message about not finding the remote shell prompt. If there are any messages from the remote host, TRAMP displays them in the buffer.
For any ‘login failed’ message from the remote host, TRAMP aborts the login attempt, and repeats the login steps.
- Upon successful login, if TRAMP recognizes the shell prompt
from the remote host, TRAMP prepares the shell environment by
turning off echoing, setting the shell prompt, and other housekeeping
chores.
Note that for the remote shell, TRAMP invokes
/bin/sh
. The remote host must recognize ‘exec /bin/sh’ and execute the appropriate shell. This shell must support Bourne shell syntax. - TRAMP executes
cd
andls
commands to find which files exist on the remote host. TRAMP sometimes usesecho
with globbing. TRAMP checks if a file or directory is writable withtest
. After each command, TRAMP parses the output from the remote host for completing the next operation. - After remote file name completion, TRAMP transfers the file
contents from the remote host.
For inline transfers, TRAMP sends a command, such as ‘mimencode -b /path/to/remote/file’, waits until the output has accumulated in the buffer, then decodes that output to produce the file’s contents.
For external transfers, TRAMP sends a command as follows:
$ scp user@host:/path/to/remote/file /tmp/tramp.4711
TRAMP reads the local temporary file /tmp/tramp.4711 into a buffer, and then deletes the temporary file.
- Edit, modify, change the buffer contents as normal, and then save the buffer with C-x C-s.
- TRAMP transfers the buffer contents to the remote host in a reverse of the process using the appropriate inline or external program.
I hope this has provided you with a basic overview of what happens behind the scenes when you open a file with TRAMP.
Next: Short introduction how to use TRAMP, Previous: An overview of TRAMP, Up: TRAMP 2.6.3 User Manual [Contents][Index]
2 Obtaining TRAMP
TRAMP is included as part of Emacs.
TRAMP is also freely packaged for download on the Internet at
https://ftp.gnu.org/gnu/tramp/. The version number of
TRAMP can be obtained by the variable tramp-version
.
For released TRAMP versions, this is a three-number string
like “2.4.5”.
A TRAMP release, which is packaged with Emacs, could differ slightly from the corresponding standalone release. This is because it isn’t always possible to synchronize release dates between Emacs and TRAMP. Such version numbers have the Emacs version number as suffix, like “2.4.5.27.2”. This means TRAMP 2.4.5 as integrated in Emacs 27.2. A complete list of TRAMP versions packaged with Emacs can be retrieved by
(assoc 'Tramp customize-package-emacs-version-alist)
TRAMP is also available as GNU ELPA package. Besides the standalone releases, further minor versions of TRAMP will appear on GNU ELPA, until the next TRAMP release appears. These minor versions have a four-number string, like “2.4.5.1”. The manual of the latest TRAMP ELPA package is located at https://elpa.gnu.org/packages/doc/tramp.html.
TRAMP development versions are available on Git servers. Development versions contain new and incomplete features. The development version of TRAMP is always the version number of the next release, plus the suffix “-pre”, like “2.4.4-pre”.
One way to obtain TRAMP from the Git server is to visit the Savannah project page at the following URL and then clicking on the Git link in the navigation bar at the top.
https://savannah.gnu.org/projects/tramp/
Another way is to follow the terminal session below:
$ cd ~/emacs $ git clone https://git.savannah.gnu.org/git/tramp.git
From behind a proxy:
$ git config --global http.proxy http://user:pwd@proxy.server.com:8080 $ git clone https://git.savannah.gnu.org/r/tramp.git
TRAMP developers:
$ git clone login@git.sv.gnu.org:/srv/git/tramp.git
After one of the above commands, ~/emacs/tramp will containing the latest version of TRAMP.
To fetch updates from the repository, use git pull
:
$ cd ~/emacs/tramp $ git pull
Run autoconf
as follows to generate an up-to-date
configure script:
$ cd ~/emacs/tramp $ autoconf
See the file INSTALL in that directory for further information on how to install TRAMP.
Next: Configuring TRAMP, Previous: Obtaining TRAMP, Up: TRAMP 2.6.3 User Manual [Contents][Index]
3 Short introduction how to use TRAMP
TRAMP extends the Emacs file name syntax by adding a remote component. A remote file name always looks like /method:user@host:/path/to/file.
You can use remote files exactly like ordinary files, that means you
can open a file or directory by C-x C-f
/method:user@host:/path/to/file RET, edit the file,
and save it. You can also mix local files and remote files in file
operations with two arguments, like copy-file
or
rename-file
. And finally, you can even run processes on a
remote host, when the buffer you call the process from has a remote
default-directory
.
- File name syntax
- Using ssh and plink
- Using su, sudo, doas and sg
- Combining ssh or plink with su, sudo or doas
- Using
sudoedit
- Using
smbclient
- Using GVFS-based methods
- Using GNOME Online Accounts based methods
- Using FUSE-based methods
- Using Android
3.1 File name syntax
Remote file names have method
, user
and host
parts prepended. All of them, and also the local file name part, are
optional, in case of a missing part a default value is assumed. The
default value for an empty local file name part is the remote user’s
home directory. The shortest remote file name is thus
/-::. The ‘-’ notation for the default method is
used for syntactical reasons, Selecting a default method.
The method
part describes the connection method used to reach
the remote host, see below.
The user
part is the user name for accessing the remote host.
For the smb method, this could also require a domain name, in
which case it is written as user%domain
.
The host
part must be a host name which can be resolved on
your local host. It could be a short host name, a fully qualified
domain name, an IPv4 or IPv6 address, TRAMP file name conventions. Some
connection methods also support a notation for the port to be used, in
which case it is written as host#port
.
3.2 Using ssh and plink
If your local host runs an SSH client, and the remote host runs an SSH server, the simplest remote file name is /ssh:user@host:/path/to/file. The remote file name /ssh:: opens a remote connection to yourself on the local host, and is often used for testing TRAMP.
On MS Windows, PuTTY is often used as the SSH client. Its plink
method can be used there to open a connection to a remote host running
an ssh
server:
/plink:user@host:/path/to/file.
3.3 Using su, sudo, doas and sg
Sometimes, it is necessary to work on your local host under different
permissions. For this, you can use the su or sudo
connection method. On OpenBSD systems, the doas connection
method offers the same functionality. These methods use ‘root’
as default user name and the return value of (system-name)
as
default host name. Therefore, it is convenient to open a file as
/sudo::/path/to/file.
The method sg stands for “switch group”; here the user name is used as the group to change to. The default host name is the same.
3.4 Combining ssh or plink with su, sudo or doas
If the su, sudo or doas option should be performed on another host, it can be combined with a leading ssh or plink option. That means that TRAMP connects first to the other host with non-administrative credentials, and changes to administrative credentials on that host afterwards. In a simple case, the syntax looks like /ssh:user@host|sudo::/path/to/file. See Declaring multiple hops in the file name.
3.5 Using sudoedit
The sudoedit method is similar to the sudo method. However, it is a different implementation: it does not keep an open session running in the background. This is for security reasons; on the backside this method has worse performance than the sudo method, it is restricted to ‘localhost’ only, and it does not support external processes.
3.6 Using smbclient
In order to access a remote MS Windows host or Samba server, the
smbclient
client is used. The remote file name syntax is
/smb:user%domain@host:/path/to/file. The first part
of the local file name is the share exported by the remote host,
‘path’ in this example.
3.7 Using GVFS-based methods
On systems which have GVFS (the GNOME Virtual File System) installed, its offered methods can be used by TRAMP. Examples are /sftp:user@host:/path/to/file, /afp:user@host:/path/to/file (accessing Apple’s AFP file system), /dav:user@host:/path/to/file, /davs:user@host:/path/to/file (for WebDAV shares) and /mtp:device:/path/to/file (for media devices).
3.8 Using GNOME Online Accounts based methods
GVFS-based methods also include GNOME Online Accounts, which support the Files service. These are the Google Drive file system, and the OwnCloud/NextCloud file system. The file name syntax here is always /gdrive:john.doe@gmail.com:/path/to/file (‘john.doe@gmail.com’ stands here for your Google Drive account), or /nextcloud:user@host#8081:/path/to/file (‘8081’ stands for the port number) for OwnCloud/NextCloud files.
3.9 Using FUSE-based methods
FUSE (Filesystem in Userspace) allows users to mount a virtual file system. It is also used by GVFS internally, but here we discuss methods which do not use the GVFS API.
A convenient way to access system storages is the rclone
program. If you have configured a storage in rclone
under a
name ‘storage’ (for example), you can access it via the remote
file name syntax /rclone:storage:/path/to/file. User
names are not needed.
On local hosts which have installed the sshfs
client for
mounting a file system based on sftp
, this method can be
used. All remote files are available via the local mount point.
TRAMP aids in mounting the file system if it isn’t mounted
yet, and it supports the access with the usual file name syntax
/sshfs:user@host:/path/to/file.
3.10 Using Android
An Android device, which is connected via USB to your local host, can
be accessed via the adb
command. No user or host name is
needed. The file name syntax is /adb::/path/to/file.
Next: Using TRAMP, Previous: Short introduction how to use TRAMP, Up: TRAMP 2.6.3 User Manual [Contents][Index]
4 Configuring TRAMP
TRAMP is initially configured to use the scp
program
to connect to the remote host. Just type C-x C-f and then enter
file name /scp:user@host:/path/to/file. For details,
See Selecting a default method, See Selecting a default user, See Selecting a default host.
For problems related to the behavior of the remote shell, See Remote shell setup hints.
For changing the connection type and file access method from the defaults to one of several other options, See Types of connections to remote hosts.
Note that some user options described in these examples are not auto loaded by Emacs. All examples require TRAMP to be installed and loaded:
(customize-set-variable 'tramp-verbose 6 "Enable remote command traces")
For functions used to configure TRAMP, the following clause may be used in your init file:
(with-eval-after-load 'tramp (tramp-change-syntax 'simplified))
Changing other variables via directory-local variables on a remote
directory must be enabled by setting enable-remote-dir-locals
to non-nil
, See (emacs)Directory Variables.
- Types of connections to remote hosts
- Inline methods
- External methods
- GVFS-based external methods
- FUSE-based external methods
- Selecting a default method
- Selecting a default user
- Selecting a default host
- Connecting to a remote host using multiple hops
- Passing firewalls
- Using Non-Standard Methods
- Selecting config files for user/host name completion
- Reusing passwords for several connections
- Reusing connection related information
- Setting own connection related information
- How TRAMP finds and uses programs on the remote host
- Remote shell setup hints
- Ssh setup hints
- FUSE setup hints
- Android shell setup hints
- Auto-save, File Lock and Backup configuration
- Protect remote files by encryption
Next: Inline methods, Up: Configuring TRAMP [Contents][Index]
4.1 Types of connections to remote hosts
Inline method and external method are the two basic types
of access methods. While they both use the same remote shell access
programs, such as rsh
, ssh
, or telnet
,
they differ in the file access methods. Choosing the right method
becomes important for editing files, transferring large files, or
operating on a large number of files.
The performance of the external methods is generally better than that of the inline methods, at least for large files. This is caused by the need to encode and decode the data when transferring inline.
The one exception to this rule are the scp-based access methods. While these methods do see better performance when actually transferring files, the overhead of the cryptographic negotiation at startup may drown out the improvement in file transfer times.
External methods should be configured in such a way that they don’t
require a password (with ssh-agent
, or similar). Modern
scp
implementations offer options to reuse existing
ssh
connections, which TRAMP enables by default if
available. If that is not possible, you should consider Reusing passwords for several connections, otherwise you will be prompted for a password for every
copy action.
Next: External methods, Previous: Types of connections to remote hosts, Up: Configuring TRAMP [Contents][Index]
4.2 Inline methods
Inline methods use the same login connection to transfer file contents. Inline methods are quick and easy for small files. They depend on the availability of suitable encoding and decoding programs on the remote host. For local source and destination, TRAMP may use built-in equivalents of such programs in Emacs.
Inline methods can work in situations where an external transfer program is unavailable. Inline methods also work when transferring files between different user identities on the same host.
TRAMP checks the remote host for the availability and
usability of one of the commands defined in
tramp-remote-coding-commands
. TRAMP uses the first
reliable command it finds. TRAMP’s search path can be
customized, see How TRAMP finds and uses programs on the remote host.
In case none of the commands are available, TRAMP first transfers a small Perl program to the remote host, and then tries to use that program for encoding and decoding.
To increase transfer speeds for large text files, TRAMP can
use compression before encoding. The user option
tramp-inline-compress-start-size
specifies the file size above
which to use this optimization. This feature depends on the
availability and usability of one of the commands defined in
tramp-inline-compress-commands
.
- rsh ¶
-
rsh
is an option for connecting to hosts within local networks sincersh
is not as secure as other methods. There should be no reason to use it, asssh
is a both a complete replacement and ubiquitous. - ssh ¶
-
ssh
is a more secure option than others to connect to a remote host.ssh
can also take extra parameters as port numbers. For example, a host on port 42 is specified as host#42 (the real host name, a hash sign, then a port number). It is the same as passing ‘-p 42’ to thessh
command. - telnet ¶
-
Connecting to a remote host with
telnet
is as insecure as the rsh method. - su ¶
-
Instead of connecting to a remote host,
su
program allows editing as another user. The host can be either ‘localhost’ or the host returned by the function(system-name)
. See Connecting to a remote host using multiple hops for an exception to this behavior. - sudo ¶
-
Similar to su method, sudo uses
sudo
.sudo
must have sufficient rights to start a shell.For security reasons, a sudo connection is disabled after a predefined timeout (5 minutes by default). This can be changed, see Setting own connection related information.
- doas ¶
-
This method is used on OpenBSD like the
sudo
command. Like the sudo method, a doas connection is disabled after a predefined timeout. - sg ¶
-
The
sg
program allows editing as different group. The host can be either ‘localhost’ or the host returned by the function(system-name)
. The user name must be specified, but it denotes a group name. See Connecting to a remote host using multiple hops for an exception to this behavior. - sshx ¶
-
Works like ssh but without the extra authentication prompts. sshx uses ‘ssh -t -t -l user -o RemoteCommand='/bin/sh -i' host’ to open a connection with a “standard” login shell. It supports changing the remote login shell
/bin/sh
.Note that sshx does not bypass authentication questions. For example, if the host key of the remote host is not known, sshx will still ask “Are you sure you want to continue connecting?”. TRAMP cannot handle such questions. Connections will have to be setup where logins can proceed without such questions.
sshx is useful for MS Windows users when
ssh
triggers an error about allocating a pseudo tty. This happens due to missing shell prompts that confuses TRAMP.sshx supports the ‘-p’ argument.
- krlogin ¶
-
This method is also similar to ssh. It uses the
krlogin -x
command only for remote host login. - ksu ¶
-
This is another method from the Kerberos suite. It behaves like su.
- plink ¶
-
plink method is for MS Windows users with the PuTTY implementation of SSH. It uses ‘plink -ssh’ to log in to the remote host. It supports changing the remote login shell
/bin/sh
.Check the ‘Share SSH connections if possible’ control for that session.
plink method supports the ‘-P’ argument.
- plinkx ¶
-
Another method using PuTTY on MS Windows with session names instead of host names. plinkx calls ‘plink -load session -t’. User names and port numbers must be defined in the session. It supports changing the remote login shell
/bin/sh
.Check the ‘Share SSH connections if possible’ control for that session.
- docker ¶
-
Integration for Docker containers. The host name may be either a running container’s name or ID, as returned by ‘docker ps’.
- podman ¶
-
Podman is an alternative to docker which may be run rootless, if desired.
- kubernetes ¶
-
Integration for containers in Kubernetes pods. The host name is a pod name returned by ‘kubectl get pods’. The first container in a pod is used.
This method does not support user names.
Next: GVFS-based external methods, Previous: Inline methods, Up: Configuring TRAMP [Contents][Index]
4.3 External methods
External methods operate over multiple channels, using the remote shell connection for some actions while delegating file transfers to an external transfer program.
External methods save on the overhead of encoding and decoding of inline methods.
Since external methods have the overhead of opening a new channel,
files smaller than tramp-copy-size-limit
still use inline
methods.
- rcp ¶
-
This method uses the
rsh
andrcp
commands to connect to the remote host and transfer files. This is the fastest access method available.The alternative method remcp uses the
remsh
andrcp
commands. - scp ¶
-
Using a combination of
ssh
to connect andscp
to transfer is the most secure. While the performance is good, it is slower than the inline methods for smaller files. Though there is no overhead of encoding and decoding of the inline methods,scp
’s cryptographic handshake negates those speed gains.ssh-based methods support ‘-p’ feature for specifying port numbers. For example, host#42 passes ‘-p 42’ in the argument list to
ssh
, and ‘-P 42’ in the argument list toscp
. - rsync ¶
-
ssh
command to connect in combination withrsync
command to transfer is similar to the scp method.rsync
performs much better thanscp
when transferring files that exist on both hosts. However, this advantage is lost if the file exists only on one side of the connection.This method supports the ‘-p’ argument.
- scpx ¶
-
scpx is useful to avoid login shell questions. It is similar in performance to scp. scpx uses ‘ssh -t -t -l user -o RemoteCommand='/bin/sh -i' host’ to open a connection. It supports changing the remote login shell
/bin/sh
.scpx is useful for MS Windows users when
ssh
triggers an error about allocating a pseudo tty. This happens due to missing shell prompts that confuses TRAMP.This method supports the ‘-p’ argument.
- pscp
- psftp ¶
-
These methods are similar to scp or sftp, but they use the
plink
command to connect to the remote host, and they usepscp
orpsftp
for transferring the files. These programs are part of PuTTY, an SSH implementation for MS Windows.They support changing the remote login shell
/bin/sh
.Check the ‘Share SSH connections if possible’ control for that session.
These methods support the ‘-P’ argument.
- fcp ¶
-
This method is similar to scp, but uses
fsh
to connect andfcp
to transfer files.fsh/fcp
, a front-end forssh
, reusessh
session by submitting several commands. This avoids the startup overhead due toscp
’s secure connection. Inline methods have similar benefits.The command used for this connection is: ‘fsh host -l user /bin/sh -i’
fsh has no inline method since the multiplexing it offers is not useful for TRAMP.
fsh
connects to remote host and TRAMP keeps that one connection open. - nc ¶
-
Using
telnet
to connect andnc
to transfer files is sometimes the only combination suitable for accessing routers or NAS hosts. These dumb devices have severely restricted local shells, such as thebusybox
and do not host any other encode or decode programs. - sudoedit ¶
-
The sudoedit method allows to edit a file as a different user on the local host. You could regard this as TRAMP’s implementation of the
sudoedit
. Contrary to the sudo method, all magic file name functions are implemented by singlesudo …
commands. The purpose is to make editing such a file as secure as possible; there must be no session running in the Emacs background which could be attacked from inside Emacs.Consequently, external processes are not implemented.
The host name of such remote file names must represent the local host. Since the default value is already proper, it is recommended not to use any host name in the remote file name, like /sudoedit::/path/to/file or /sudoedit:user@:/path/to/file.
Like the sudo method, a sudoedit password expires after a predefined timeout.
- ftp ¶
-
When TRAMP uses ftp, it forwards requests to whatever ftp program is specified by Ange FTP. This external program must be capable of servicing requests from TRAMP.
- smb ¶
-
This non-native TRAMP method connects via the Server Message Block (SMB) networking protocol to hosts running file servers that are typically based on Samba or MS Windows.
Using
smbclient
requires a few tweaks when working with TRAMP:The first directory in the localname must be a share name on the remote host.
Since some SMB share names end in the
$
character, TRAMP must use$$
when specifying those shares to avoid environment variable substitutions.When TRAMP is not specific about the share name or uses the generic remote directory /,
smbclient
returns all available shares.Since SMB authentication is based on each SMB share, TRAMP prompts for a password even when accessing a different share on the same SMB host. This prompting can be suppressed by Reusing passwords for several connections.
To accommodate user name/domain name syntax required by MS Windows authorization, TRAMP provides for an extended syntax in
user%domain
format (whereuser
is the user name,%
is the percent symbol, anddomain
is the MS Windows domain name). An example:/smb:daniel%BIZARRE@melancholia:/daniel$$/.emacs
where user
daniel
connects as a domain user to the SMB hostmelancholia
in the MS Windows domainBIZARRE
to edit .emacs located in the home directory (sharedaniel$
).Alternatively, for local WINS users (as opposed to domain users), substitute the domain name with the name of the local host in UPPERCASE as shown here:
/smb:daniel%MELANCHOLIA@melancholia:/daniel$$/.emacs
where user
daniel
connects as local user to the SMB hostmelancholia
in the local domainMELANCHOLIA
to edit .emacs located in the home directory (sharedaniel$
).The domain name and user name are optional for
smbclient
authentication. When user name is not specified,smbclient
uses the anonymous user (without prompting for password). This behavior is unlike other TRAMP methods, where local user name is substituted.The smb method is unavailable if Emacs is run under a local user authentication context in MS Windows. However such users can still access remote files using UNC file names instead of TRAMP:
//melancholia/daniel$$/.emacs
UNC file name specification does not allow the specification of a different user name for authentication like the
smbclient
can. - adb ¶
-
This method uses Android Debug Bridge program for accessing Android devices. The Android Debug Bridge must be installed locally for TRAMP to work. Some GNU/Linux distributions provide Android Debug Bridge as an installation package. Alternatively, the program is installed as part of the Android SDK. TRAMP finds the
adb
program either via thePATH
environment variable or the absolute path set in the user optiontramp-adb-program
.TRAMP connects to Android devices with adb only when the user option
tramp-adb-connect-if-not-connected
is notnil
. Otherwise, the connection must be established outside Emacs.TRAMP does not require a host name part of the remote file name when a single Android device is connected to
adb
. TRAMP instead uses /adb:: as the default name.adb devices
, run in a shell outside Emacs, shows available host names.adb method normally does not need user name to authenticate on the Android device because it runs under the
adbd
process. But when a user name is specified, however, TRAMP applies ansu
in the syntax. When authentication does not succeed, especially on un-rooted Android devices, TRAMP displays login errors.For Android devices connected through TCP/IP, a port number can be specified using device#42 host name syntax or TRAMP can use the default value as declared in
adb
command. Port numbers are not applicable to Android devices connected through USB.
Next: FUSE-based external methods, Previous: External methods, Up: Configuring TRAMP [Contents][Index]
4.4 GVFS-based external methods
GVFS is the virtual file system for the GNOME Desktop, https://en.wikipedia.org/wiki/GVFS. Remote files on GVFS are mounted locally through FUSE and TRAMP uses this locally mounted directory internally.
Emacs uses the D-Bus mechanism to communicate with GVFS. Emacs must have the message bus system, D-Bus integration active, see (dbus)D-Bus.
- afp ¶
-
This method is for connecting to remote hosts with the Apple Filing Protocol for accessing files on macOS volumes. TRAMP access syntax requires a leading volume (share) name, for example: /afp:user@host:/volume.
- dav
- davs ¶
-
dav method provides access to WebDAV files and directories based on standard protocols, such as HTTP. davs does the same but with SSL encryption. Both methods support the port numbers.
Paths being part of the WebDAV volume to be mounted by GVFS, as it is common for OwnCloud or NextCloud file names, are not supported by these methods. See method nextcloud for handling them.
- gdrive ¶
-
Via the gdrive method it is possible to access your Google Drive online storage. User and host name of the remote file name are your email address of the Google Drive credentials, like /gdrive:john.doe@gmail.com:/. These credentials must be populated in your
Online Accounts
application outside Emacs.Since Google Drive uses cryptic blob file names internally, TRAMP works with the
display-name
of the files. This could produce unexpected behavior in case two files in the same directory have the samedisplay-name
, such a situation must be avoided. - mtp ¶
-
Media devices, like cell phones, tablets, cameras, can be accessed via the mtp method. Just the device name is needed in order to specify the host in the file name. However, the device must already be connected via USB, before accessing it. Possible device names are visible via host name completion, File name completion.
Depending on the device type, the access could be read-only. Some devices are accessible under different names in parallel, offering different parts of their file system.
TRAMP does not require a host name as part of the remote file name when a single media device is connected. TRAMP instead uses /mtp:: as the default name.
- nextcloud ¶
-
As the name indicates, the method nextcloud allows you to access OwnCloud or NextCloud hosted files and directories. Like the gdrive method, your credentials must be populated in your
Online Accounts
application outside Emacs. The method supports port numbers. - sftp ¶
-
This method uses
sftp
in order to securely access remote hosts.sftp
is a more secure option for connecting to hosts that for security reasons refusessh
connections.When there is a respective entry in your
ssh
configuration, do not set the RemoteCommand option.
- User Option: tramp-gvfs-methods ¶
This user option is a list of external methods for GVFS. By default, this list includes afp, dav, davs, gdrive, mtp, nextcloud and sftp. Other methods to include are ftp, http, https and smb. These methods are not intended to be used directly as GVFS-based method. Instead, they are added here for the benefit of Archive file names.
If you want to use GVFS-based ftp or smb methods, you must add them to
tramp-gvfs-methods
, and you must disable the corresponding TRAMP package by settingtramp-ftp-method
ortramp-smb-method
tonil
, respectively:(add-to-list 'tramp-gvfs-methods "ftp") (customize-set-variable 'tramp-ftp-method nil)
Next: Selecting a default method, Previous: GVFS-based external methods, Up: Configuring TRAMP [Contents][Index]
4.5 FUSE-based external methods
Besides GVFS, there are other virtual file systems using the FUSE interface. Remote files are mounted locally through FUSE and TRAMP uses this locally mounted directory internally. When possible, TRAMP maps the remote file names to their respective local file name, and applies the file name operation on them. For some of the file name operations this is not possible, TRAMP emulates those operations otherwise.
- rclone ¶
-
The program
rclone
allows to access different system storages in the cloud, see https://rclone.org/ for a list of supported systems. If therclone
program isn’t found in yourPATH
environment variable, you can tell TRAMP its absolute path via the user optiontramp-rclone-program
.A system storage must be configured via the
rclone config
command, outside Emacs. If you have configured a storage inrclone
under a name ‘storage’ (for example), you could access it via the remote file name/rclone:storage:/path/to/file
User names are part of the
rclone
configuration, and not needed in the remote file name. If a user name is contained in the remote file name, it is ignored.Internally, TRAMP mounts the remote system storage at location /tmp/tramp.rclone.storage, with storage being the name of the configured system storage.
The mount point and optional flags to the different rclone operations could be passed as connection properties, See Setup of rclone method.
Access via rclone is slow. If you have an alternative method for accessing the system storage, you should use it. GVFS-based external methods for example, methods gdrive and nextcloud.
- sshfs ¶
-
On local hosts which have installed the
sshfs
client for mounting a file system based onsftp
, this method can be used, see https://github.com/libfuse/sshfs/blob/master/README.rst/. If thesshfs
program isn’t found in yourPATH
environment variable, you can tell TRAMP its absolute path via the user optiontramp-sshfs-program
.All remote files are available via the local mount point. TRAMP aids in mounting the file system if it isn’t mounted yet. The remote file name syntax is
/sshfs:user@host#port:/path/to/file
User name and port number are optional. This method does not support password handling, the file system must either be mounted already, or the connection must be established passwordless via ssh keys.
The mount point and mount arguments could be passed as connection properties, See Setup of sshfs method.
Next: Selecting a default user, Previous: FUSE-based external methods, Up: Configuring TRAMP [Contents][Index]
4.6 Selecting a default method
In a remote file name, the use of a default method is indicated by the pseudo method -, TRAMP file name conventions.
- User Option: tramp-default-method ¶
Default method is for transferring files. The user option
tramp-default-method
sets it. TRAMP uses this user option to determine the default method for remote file names that do not have one specified.(customize-set-variable 'tramp-default-method "ssh")
- User Option: tramp-default-method-alist ¶
Default methods for transferring files can be customized for specific user and host combinations through the user option
tramp-default-method-alist
.For example, the following two lines specify to use the ssh method for all user names matching ‘john’ and the rsync method for all host names matching ‘lily’. The third line specifies to use the su method for the user ‘root’ on the host ‘localhost’.
(add-to-list 'tramp-default-method-alist '("" "john" "ssh")) (add-to-list 'tramp-default-method-alist '("lily" "" "rsync")) (add-to-list 'tramp-default-method-alist '("\\`localhost\\'" "\\`root\\'" "su"))
External methods performance faster for large files. see Inline methods. see External methods.
Choosing the access method also depends on the security environment. For example, rsh and telnet methods that use clear text password transfers are inappropriate for over the Internet connections. Secure remote connections should use ssh that provide encryption.
4.6.1 Which method to use?
TRAMP provides maximum number of choices for maximum flexibility. Choosing which method depends on the hosts, clients, network speeds, and the security context.
Start by using an inline method.
External methods might be more efficient for large files, but most TRAMP users edit small files more often than large files.
Enable compression, tramp-inline-compress-start-size
, for a
performance boost for large files with inline methods.
Since ssh
has become the most common method of remote host
access and it has the most reasonable security protocols, use
ssh method. Typical ssh usage to edit the
/etc/motd file on the otherhost:
C-x C-f /ssh:root@otherhost:/etc/motd RET
If ssh is unavailable for whatever reason, look for other obvious options. For MS Windows, try the plink method1. For Kerberos, try krlogin.
For editing local files as su or sudo methods, try the shortened syntax of ‘root’:
C-x C-f /su::/etc/motd RET
For editing large files, scp is faster than ssh. pscp is faster than plink. But this speed improvement is not always true.
When copying large files between two different remote hosts via
scp, set tramp-use-scp-direct-remote-copying
to
non-nil
.
Next: Selecting a default host, Previous: Selecting a default method, Up: Configuring TRAMP [Contents][Index]
4.7 Selecting a default user
- User Option: tramp-default-user ¶
A TRAMP file name can omit the user name part since TRAMP substitutes the currently logged-in user name. However this substitution can be overridden with
tramp-default-user
. For example:(customize-set-variable 'tramp-default-user "root")
- User Option: tramp-default-user-alist ¶
Instead of a single default user,
tramp-default-user-alist
allows multiple default user values based on access method or host name combinations. The alist can hold multiple values. For example, to use the ‘john’ as the default user for the domain ‘somewhere.else’ only:(add-to-list 'tramp-default-user-alist '("ssh" ".*\\.somewhere\\.else\\'" "john"))
A Caution: TRAMP will override any default user specified in the configuration files outside Emacs, such as ~/.ssh/config. To stop TRAMP from applying the default value, set the corresponding alist entry to
nil
:(add-to-list 'tramp-default-user-alist '("ssh" "\\`here\\.somewhere\\.else\\'" nil))
The last entry in
tramp-default-user-alist
should be reserved for catch-all or most often used login.(add-to-list 'tramp-default-user-alist '(nil nil "jonas") t)
Next: Connecting to a remote host using multiple hops, Previous: Selecting a default user, Up: Configuring TRAMP [Contents][Index]
4.8 Selecting a default host
- User Option: tramp-default-host ¶
When host name is omitted, TRAMP substitutes the value from the
tramp-default-host
user option. It is initially populated with the local host name where Emacs is running. The default method, default user and default host can be overridden as follows:(custom-set-variables '(tramp-default-method "ssh") '(tramp-default-user "john") '(tramp-default-host "target"))
With all defaults set, ‘/-::’ will connect TRAMP to John’s home directory on
target
viassh
.
- User Option: tramp-default-host-alist ¶
Instead of a single default host,
tramp-default-host-alist
allows multiple default host values based on access method or user name combinations. The alist can hold multiple values. Whiletramp-default-host
is sufficient in most cases, some methods, like adb, require defaults overwritten.
Next: Passing firewalls, Previous: Selecting a default host, Up: Configuring TRAMP [Contents][Index]
4.9 Connecting to a remote host using multiple hops
Multi-hops are methods to reach hosts behind firewalls or to reach the outside world from inside a bastion host. With multi-hops, TRAMP can negotiate these hops with the appropriate user/host authentication at each hop. All methods until now have been the single hop kind, where the start and end points of the connection did not have intermediate check points.
- User Option: tramp-default-proxies-alist ¶
tramp-default-proxies-alist
specifies proxy hosts to pass through. This user option is list of triples consisting of(host user proxy)
.The first match is the proxy host through which passes the file name and the target host matching user@host. host and user are regular expressions or
nil
, interpreted as a regular expression which always matches.proxy is a literal TRAMP file name whose local name part is ignored, and the method and user name parts are optional.
The method must be an inline method (see Inline methods). If proxy is
nil
, no additional hop is required reaching user@host.For example, to pass through the host ‘bastion.your.domain’ as user ‘bird’ to reach remote hosts outside the local domain:
(add-to-list 'tramp-default-proxies-alist '("\\." nil "/ssh:bird@bastion.your.domain:")) (add-to-list 'tramp-default-proxies-alist '("\\.your\\.domain\\'" nil nil))
Note:
add-to-list
adds elements at the beginning of a list. Therefore, most relevant rules must come last in the list.Proxy hosts can be cascaded in the alist. If there is another host called ‘jump.your.domain’, which is the only host allowed to connect to ‘bastion.your.domain’, then:
(add-to-list 'tramp-default-proxies-alist '("\\`bastion\\.your\\.domain\\'" "\\`bird\\'" "/ssh:jump.your.domain:"))
proxy can take patterns
%h
or%u
for host or user respectively. Ports or domains, if they are part of a hop file name, are not expanded by those patterns.To login as ‘root’ on remote hosts in the domain ‘your.domain’, but login as ‘root’ is disabled for non-local access, then use this alist entry:
(add-to-list 'tramp-default-proxies-alist '("\\.your\\.domain\\'" "\\`root\\'" "/ssh:%h:"))
Opening /sudo:randomhost.your.domain: first connects to ‘randomhost.your.domain’ via
ssh
under your account name, and then performssudo -u root
on that host.It is key for the sudo method in the above example to be applied on the host after reaching it and not on the local host. TRAMP checks therefore, that the host name for such hops matches the host name of the previous hop.
host, user and proxy can also take Lisp forms. These forms when evaluated must return either a string or
nil
.To generalize (from the previous example): For all hosts, except my local one, first connect via
ssh
, and then applysudo -u root
:(add-to-list 'tramp-default-proxies-alist '(nil "\\`root\\'" "/ssh:%h:")) (add-to-list 'tramp-default-proxies-alist `(,(regexp-quote (system-name)) nil nil))
Passing through hops involves dealing with restricted shells, such as
rbash
. If TRAMP is made aware, then it would use
them for proxies only.
- User Option: tramp-restricted-shell-hosts-alist ¶
An alist of regular expressions of hosts running restricted shells, such as
rbash
. TRAMP will then use them only as proxies.To specify the bastion host from the example above as running a restricted shell:
(add-to-list 'tramp-restricted-shell-hosts-alist "\\`bastion\\.your\\.domain\\'")
Next: Using Non-Standard Methods, Previous: Connecting to a remote host using multiple hops, Up: Configuring TRAMP [Contents][Index]
4.10 Passing firewalls
Sometimes, it is not possible to reach a remote host directly. A firewall might be in the way, which could be passed via a proxy server.
Both OpenSSH and PuTTY support such proxy settings, using an HTTP
tunnel via the CONNECT
command (conforming to RFC 2616, 2817
specifications). Proxy servers using HTTP 1.1 or later protocol
support this command.
4.10.1 Tunneling with ssh
With ssh
, you could use the ProxyCommand entry in
~/.ssh/config:
Host host.other.domain ProxyCommand nc -X connect -x proxy.your.domain:3128 %h %p
nc
is BSD’s netcat program, which establishes HTTP tunnels.
Any other program with such a feature could be used as well.
In the example, opening /ssh:host.your.domain: passes the HTTP proxy server ‘proxy.your.domain’ on port 3128.
4.10.2 Tunneling with PuTTY
PuTTY does not need an external program, HTTP tunnel support is built-in. In the PuTTY config program, create a session for ‘host.your.domain’. In the Connection/Data entry, select the HTTP option, and add ‘proxy.your.domain’ as Proxy hostname, and 3128 as Port.
Opening /plinkx:host.your.domain: passes the HTTP proxy server ‘proxy.your.domain’ on port 3128.
Next: Selecting config files for user/host name completion, Previous: Passing firewalls, Up: Configuring TRAMP [Contents][Index]
4.11 Using Non-Standard Methods
The tramp-methods
variable currently has an exhaustive list of
predefined methods. Any part of this list can be modified with more
suitable settings. Refer to the Lisp documentation of that variable,
accessible with C-h v tramp-methods RET.
In the ELPA archives, there are several examples of such extensions. They can be installed with Emacs’s Package Manager. This includes
- ‘lxc-tramp’ ¶
-
Integration for LXC containers. A container is accessed via /lxc:container:/path/to/file, ‘container’ has the same meaning as with the docker method. A ‘user’ specification is ignored.
- ‘lxd-tramp’ ¶
-
Integration for LXD containers. A container is accessed via /lxd:user@container:/path/to/file, ‘user’ and ‘container’ have the same meaning as with the docker method.
- ‘magit-tramp’ ¶
-
Browsing Git repositories with
magit
. A versioned file is accessed via /git:rev@root-dir:/path/to/file. ‘rev’ is a Git revision, and ‘root-dir’ is a virtual host name for the root directory, specified inmagit-tramp-hosts-alist
. - ‘tramp-hdfs’ ¶
-
Access of a hadoop/hdfs file system. A file is accessed via /hdfs:user@node:/path/to/file, where ‘user’ is the user that you want to use, and ‘node’ is the name of the hadoop server.
- ‘tramp-nspawn’ ¶
-
Access to environments provided by systemd-nspawn. A file is accessed via /nspawn:user@container:/path/to/file, where ‘user’ is the (optional) user that you want to use, and ‘container’ is the container to connect to. systemd-nspawn and its container utilities often require super user access to run, use multi-hop file names with doas or sudo to raise your privileges.
- ‘vagrant-tramp’ ¶
-
Convenience method to access vagrant boxes. It is often used in multi-hop file names like /vagrant:box|sudo:box:/path/to/file, where ‘box’ is the name of the vagrant box.
Next: Reusing passwords for several connections, Previous: Using Non-Standard Methods, Up: Configuring TRAMP [Contents][Index]
4.12 Selecting config files for user/host name completion
tramp-completion-function-alist
uses predefined files for user
and host name completion (see File name completion). For each
method, it keeps a set of configuration files and a function that can
parse that file. Each entry in tramp-completion-function-alist
is of the form (method pair1 pair2 …).
Each pair is composed of (function file). function is responsible for extracting user names and host names from file for completion. There are two functions which access this variable:
- Function: tramp-get-completion-function method ¶
This function returns the list of completion functions for method.
Example:
(tramp-get-completion-function "rsh") ⇒ ((tramp-parse-rhosts "/etc/hosts.equiv") (tramp-parse-rhosts "~/.rhosts"))
- Function: tramp-set-completion-function method function-list ¶
This function sets function-list as list of completion functions for method.
Example:
(tramp-set-completion-function "ssh" '((tramp-parse-sconfig "/etc/ssh_config") (tramp-parse-sconfig "~/.ssh/config"))) ⇒ ((tramp-parse-sconfig "/etc/ssh_config") (tramp-parse-sconfig "~/.ssh/config"))
The following predefined functions parsing configuration files exist:
tramp-parse-rhosts
¶-
This function parses files which are syntactical equivalent to ~/.rhosts. It returns both host names and user names, if specified.
tramp-parse-shosts
¶-
This function parses files which are syntactical equivalent to ~/.ssh/known_hosts. Since there are no user names specified in such files, it can return host names only.
tramp-parse-sconfig
¶-
This function returns the host nicknames defined by Host entries in ~/.ssh/config style files.
tramp-parse-shostkeys
¶-
SSH2 parsing of directories /etc/ssh2/hostkeys/* and ~/ssh2/hostkeys/*. Hosts are coded in file names hostkey_portnumber_host-name.pub. User names are always
nil
. tramp-parse-sknownhosts
¶-
Another SSH2 style parsing of directories like /etc/ssh2/knownhosts/* and ~/ssh2/knownhosts/*. This case, hosts names are coded in file names host-name.algorithm.pub. User names are always
nil
. tramp-parse-hosts
¶-
A function dedicated to /etc/hosts for host names.
tramp-parse-passwd
¶-
A function which parses /etc/passwd for user names.
tramp-parse-etc-group
¶-
A function which parses /etc/group for group names.
tramp-parse-netrc
¶-
A function which parses ~/.netrc and ~/.authinfo-style files.
To keep a custom file with custom data in a custom structure, a custom function has to be provided. This function must meet the following conventions:
- Function: my-tramp-parse file ¶
file must be either a file on the host, or
nil
. The function must return a list of (user host), which are taken as candidates for completion for user and host names.Example:
(my-tramp-parse "~/.my-tramp-hosts") ⇒ ((nil "toto") ("daniel" "melancholia"))
Next: Reusing connection related information, Previous: Selecting config files for user/host name completion, Up: Configuring TRAMP [Contents][Index]
4.13 Reusing passwords for several connections
To avoid repeated prompts for passwords, consider native caching
mechanisms, such as ssh-agent
for ssh-like
methods, or pageant
for plink-like methods.
TRAMP offers alternatives when native solutions cannot meet the need.
4.13.1 Using an authentication file
The package auth-source.el, originally developed for No Gnus,
reads passwords from different sources, See (auth)auth-source. The default authentication file is
~/.authinfo.gpg, but this can be changed via the user option
auth-sources
.
A typical entry in the authentication file:
machine melancholia port scp login daniel password geheim
The port can take any TRAMP method (see Inline methods, see External methods). Omitting port values matches all TRAMP methods. Domain and ports, as used in TRAMP file name syntax, must be appended to the machine and login items:
machine melancholia#4711 port davs login daniel%BIZARRE password geheim
For the methods doas, sudo and sudoedit the password of the user requesting the connection is needed, and not the password of the target user. If these connections happen on the local host, an entry with the local user and local host is used:
machine host port sudo login user password secret
user and host are the strings returned by
(user-login-name)
and (system-name)
. If one of these
methods is connected via a multi hop (see Connecting to a remote host using multiple hops), the
credentials of the previous hop are used.
If no proper entry exists, the password is read
interactively. After successful login (verification of the password),
Emacs offers to save a corresponding entry for further use by
auth-source
backends which support this. This can be changed
by setting the user option auth-source-save-behavior
to nil
.
Set auth-source-debug
to t
to debug messages.
Note that auth-source.el is not used for ftp
connections, because TRAMP passes the work to Ange FTP. If
you want, for example, use your ~/.authinfo.gpg authentication
file, you must customize ange-ftp-netrc-filename
:
(customize-set-variable 'ange-ftp-netrc-filename "~/.authinfo.gpg")
In case you do not want to use an authentication file for TRAMP passwords, use connection-local variables like this:
(connection-local-set-profile-variables 'remote-without-auth-sources '((auth-sources . nil)))
(connection-local-set-profiles '(:application tramp) 'remote-without-auth-sources)
4.13.2 Caching passwords
TRAMP can cache passwords as entered and reuse when needed for the same user or host name independent of the access method.
password-cache-expiry
sets the duration (in seconds) the
passwords are remembered. Passwords are never saved permanently nor
can they extend beyond the lifetime of the current Emacs session. Set
password-cache-expiry
to nil
to disable expiration.
Set password-cache
to nil
to disable password caching.
Next: Setting own connection related information, Previous: Reusing passwords for several connections, Up: Configuring TRAMP [Contents][Index]
4.14 Reusing connection related information
For faster initial connection times, TRAMP stores previous
connection properties in a file specified by the user option
tramp-persistency-file-name
.
The default file name for tramp-persistency-file-name
is
~/.emacs.d/tramp.
TRAMP reads this file during Emacs startup, and writes to it when exiting Emacs. Delete this file for TRAMP to recreate a new one on next Emacs startup.
Set tramp-persistency-file-name
to nil
to disable
storing connections persistently.
When TRAMP detects a change in the operating system version in
a remote host (via the command uname -sr
), it flushes all
connection related information for that host and creates a new entry.
Next: How TRAMP finds and uses programs on the remote host, Previous: Reusing connection related information, Up: Configuring TRAMP [Contents][Index]
4.15 Setting own connection related information
For more precise customization, parameters specified by
tramp-methods
can be overwritten manually.
Set tramp-connection-properties
to manually override
tramp-methods
. Properties in this list are in the form
(regexp property value)
. regexp
matches remote file names. Use nil
to match all.
property is the property’s name, and value is the
property’s value.
property is any method specific parameter contained in
tramp-methods
. The parameter key in tramp-methods
is a
symbol name tramp-<foo>
. To overwrite that property, use the
string "<foo>" for property. For example, this changes the
remote shell:
(add-to-list 'tramp-connection-properties (list (regexp-quote "/ssh:user@randomhost.your.domain:") "remote-shell" "/bin/ksh"))
(add-to-list 'tramp-connection-properties (list (regexp-quote "/ssh:user@randomhost.your.domain:") "remote-shell-login" '("-")))
The parameters tramp-remote-shell
and
tramp-remote-shell-login
in tramp-methods
now have new
values for the remote host.
property could also be any property found in
tramp-persistency-file-name
.
4.15.1 Relevant connection properties to override
Not all connection properties need to be changed. The most relevant properties are listed here:
- "login-program"
The property "login-program" stores the program to be used to connect to the remote host. Sometimes, the program might have another name on your host, or it might be located in another path. In this case, you can overwrite the default value, which is special for every connection method. It is used in all connection methods of tramp-sh.el.
- "login-args"
"login-args" specifies a list of lists of arguments to pass to "login-program". Read the docstring of
tramp-methods
how to construct these lists. - "remote-shell"
This property tells TRAMP which remote shell to apply on the remote host. It is used in all connection methods of tramp-sh.el. The default value is "/bin/sh".
- "remote-shell-login"
A property to be used in conjunction with "remote-shell". It specifies, which shell argument triggers a login shell. Its default value is "-l", but some shells, like
ksh
, prefer "-". - "session-timeout"
All tramp-sh.el based methods accept the property "session-timeout". This is the time (in seconds) after a connection is disabled for security reasons, and must be reestablished. A value of
nil
disables this feature. Most of the methods do not set this property except the sudo and doas methods, which use predefined values. - "~"
"~user"This is the home directory on the remote host. Setting this connection property helps especially for methods which cannot expand to a remote home directory, like adb, rclone and sshfs. Expanding ~ to home directory for an example.
- "tmpdir"
The temporary directory on the remote host. If not specified, the default value is "/data/local/tmp" for the adb method, "/C$/Temp" for the smb method, and "/tmp" otherwise.
- "direct-async-process"
When this property is non-
nil
, an alternative, more performant implementation ofmake-process
andstart-file-process
is applied. The connection method must also be marked with a non-nil
tramp-direct-async
parameter intramp-methods
. Improving performance of asynchronous remote processes for a discussion of constraints. - "posix"
Connections using the smb method check, whether the remote host supports posix commands. If the remote host runs Samba, it confirms this capability. However, some very old Samba versions have errors in their implementation. In order to suppress the posix commands for those hosts, the property "posix" should be set to
nil
.The default value of this property is
t
(not specified intramp-methods
). If the remote host runs native MS Windows, this property has no effect. - "mount-point"
The directory file name an FUSE-based file system is mounted on. The default value of this property is "/tmp/tramp.method.user@host#port" (not specified in
tramp-methods
). - "mount-args"
"copyto-args"
"moveto-args"
"about-args"These properties keep optional flags to the different rclone operations. See their default values in
tramp-methods
if you want to change their values.
Next: Remote shell setup hints, Previous: Setting own connection related information, Up: Configuring TRAMP [Contents][Index]
4.16 How TRAMP finds and uses programs on the remote host
TRAMP requires access to and rights to several commands on
remote hosts: ls
, test
, find
and
cat
.
Besides there are other required programs for Inline methods and External methods of connection.
To improve performance and accuracy of remote file access,
TRAMP uses perl
(or perl5
) and
grep
when available.
- User Option: tramp-remote-path ¶
tramp-remote-path
specifies which remote directory paths TRAMP can search for How TRAMP finds and uses programs on the remote host.TRAMP uses standard defaults, such as /bin and /usr/bin, which are reasonable for most hosts. To accommodate differences in hosts and paths, for example, /bin:/usr/bin on Debian GNU/Linux or /usr/xpg4/bin:/usr/ccs/bin:/usr/bin:/opt/developerstudio12.6/bin on Solaris, TRAMP queries the remote host with
getconf PATH
and updates the symboltramp-default-remote-path
.For instances where hosts keep obscure locations for paths for security reasons, manually add such paths to local .emacs as shown below for TRAMP to use when connecting.
(add-to-list 'tramp-remote-path "/usr/local/perl/bin")
Another way to find the remote path is to use the path assigned to the remote user by the remote host. TRAMP does not normally retain this remote path after login. However,
tramp-own-remote-path
preserves the path value, which can be used to updatetramp-remote-path
.(add-to-list 'tramp-remote-path 'tramp-own-remote-path)
Note that this works only if your remote
/bin/sh
shell supports the login argument ‘-l’.
tramp-remote-path
can also be set per host via connection-local
variables.
You could define your own search directories like this:
(connection-local-set-profile-variables 'remote-path-with-bin '((tramp-remote-path . ("~/bin" tramp-default-remote-path))))
(connection-local-set-profile-variables 'remote-path-with-apply-pub-bin '((tramp-remote-path . ("/appli/pub/bin" tramp-default-remote-path))))
(connection-local-set-profiles '(:application tramp :machine "randomhost") 'remote-path-with-bin)
(connection-local-set-profiles '(:application tramp :user "anotheruser" :machine "anotherhost") 'remote-path-with-apply-pub-bin)
When remote search paths are changed, local TRAMP caches must be recomputed. To force TRAMP to recompute afresh, call M-x tramp-cleanup-this-connection RET or friends (see Cleanup remote connections).
Next: Ssh setup hints, Previous: How TRAMP finds and uses programs on the remote host, Up: Configuring TRAMP [Contents][Index]
4.17 Remote shell setup hints
4.17.1 Changing the default remote or local shell
By default, TRAMP uses the command /bin/sh
for
starting a shell on the remote host. This can be changed by setting
the connection property "remote-shell"; see Setting own connection related information. If you want, for example, use
/usr/bin/zsh
on a remote host, you might apply
(add-to-list 'tramp-connection-properties (list (regexp-quote "/sshx:user@host:") "remote-shell" "/usr/bin/zsh"))
This works only for connection methods which allow to override the remote login shell, like sshx or plink. See Inline methods and External methods for connection methods which support this.
This approach has also the advantage, that settings in
tramp-sh-extra-args
will be applied. For zsh
, the
trouble with the shell prompt due to set zle options will be avoided.
For bash
, loading ~/.editrc or ~/.inputrc is
suppressed.
Similar problems can happen with the local shell TRAMP uses to
create a process. By default, it uses the command /bin/sh
for this, which could also be a link to another shell. In order to
overwrite this, you might apply
(customize-set-variable 'tramp-encoding-shell "/usr/bin/zsh")
This uses also the settings in tramp-sh-extra-args
.
Note: If you use an ssh-based method for connection,
do not set the RemoteCommand option in your
ssh
configuration to something like screen
. If
used, RemoteCommand must open an interactive shell on the
remote host. On the other hand, some ssh-based methods, like
sshx or scpx, silently overwrite a
RemoteCommand option of the configuration file.
4.17.2 Other remote shell setup hints
TRAMP checks for the availability of standard programs in the
usual locations. Common tactics include successively trying
test -e
, /usr/bin/test -e
, and /bin/test
-e
. ls -d
is another approach. But these approaches do not
help with these new login patterns.
When TRAMP encounters two-factor logins or additional challenge questions, such as entering birth date or security code or passphrase, TRAMP needs a few more configuration steps to accommodate them.
The difference between a password prompt and a passphrase prompt is that the password for completing the login while the passphrase is for authorizing access to local authentication information, such as the ssh key.
There is no one configuration to accommodate all the variations in login security, especially not the exotic ones. However, TRAMP provides a few tweaks to address the most common ones.
tramp-shell-prompt-pattern
¶-
tramp-shell-prompt-pattern
is for remote login shell prompt, which may not be the same as the local login shell prompt,shell-prompt-pattern
. Since most hosts use identical prompts, TRAMP sets a similar default value for both prompts. tramp-password-prompt-regexp
tramp-otp-password-prompt-regexp
tramp-wrong-passwd-regexp
¶-
TRAMP uses
tramp-password-prompt-regexp
to distinguish between prompts for passwords and prompts for passphrases. By default,tramp-password-prompt-regexp
handles the detection in English language environments. See a localization example below:(customize-set-variable 'tramp-password-prompt-regexp (concat "^.*" (regexp-opt '("passphrase" "Passphrase" ;; English "password" "Password" ;; Deutsch "passwort" "Passwort" ;; Français "mot de passe" "Mot de passe") t) ".*:\0? *"))
This user option is, by default, initialized from
password-word-equivalents
when TRAMP is loaded, and it is usually more convenient to add new passphrases to that user option instead of altering this user option.The user option
tramp-otp-password-prompt-regexp
has a similar purpose, but for one-time passwords. Those passwords are not cached by TRAMP for reuse.Similar localization may be necessary for handling wrong password prompts, for which TRAMP uses
tramp-wrong-passwd-regexp
. tramp-terminal-type
¶-
TRAMP uses the user option
tramp-terminal-type
to set the remote environment variableTERM
for the shells it runs. By default, it is "dumb", but this could be changed. A dumb terminal is best suited to run the background sessions of TRAMP. However, running interactive remote shells might require a different setting. This could be achieved by tweaking theTERM
environment variable inprocess-environment
.(let ((process-environment (cons "TERM=xterm-256color" process-environment))) (shell))
- Determining a TRAMP session ¶
-
Sometimes, it is needed to identify whether a shell runs under TRAMP control. The setting of environment variable
TERM
will help:if test "$TERM" = "dumb"; then ... fi
Another possibility is to check the environment variable
INSIDE_EMACS
. Like for all subprocesses of Emacs, this is set to the version of the parent Emacs process. TRAMP adds its own package version to this string, which could be used for further tests in an inferior shell. The string of that environment variable looks always likeecho $INSIDE_EMACS ⇒ 27.2,tramp:2.4.5
tset
and other questions ¶-
To suppress inappropriate prompts for terminal type, TRAMP sets the
TERM
environment variable before the remote login process begins via the user optiontramp-terminal-type
(see above). This will silence commontset
related prompts.TRAMP’s strategy for handling such prompts (commonly triggered from login scripts on remote hosts) is to set the environment variables so that no prompts interrupt the shell initialization process.
An alternative approach is to configure TRAMP with strings that can identify such questions using
tramp-actions-before-shell
. Example:(defconst my-tramp-prompt-regexp "Enter the birth date of your mother:\\s-*" "Regular expression matching my login prompt question.")
(defun my-tramp-action (proc vec) "Enter \"19000101\" in order to give a correct answer." (save-window-excursion (with-current-buffer (tramp-get-connection-buffer vec) (tramp-message vec 6 "\n%s" (buffer-string)) (tramp-send-string vec "19000101"))))
(add-to-list 'tramp-actions-before-shell '(my-tramp-prompt-regexp my-tramp-action))
The regular expressions used in
tramp-actions-before-shell
must match the end of the connection buffer. Due to performance reasons, this search starts at the end of the buffer, and it is limited to 256 characters backwards. - Conflicting names for users and variables in .profile
-
When a user name is the same as a variable name in a local file, such as .profile, then TRAMP may send incorrect values for environment variables. To avoid incorrect values, change the local variable name to something different from the user name. For example, if the user name is
FRUMPLE
, then change the variable name toFRUMPLE_DIR
. - Non-Bourne commands in .profile
-
When the remote host’s .profile is also used for shells other than Bourne shell, then some incompatible syntaxes for commands in .profile may trigger errors in Bourne shell on the host and may not complete client’s TRAMP connections.
One example of a Bourne shell incompatible syntax in .profile: using
export FOO=bar
instead ofFOO=bar; export FOO
. After remote login, TRAMP will trigger an error during its execution of/bin/sh
on the remote host because Bourne shell does not recognize the export command as entered in .profile.Likewise, (
~
) character in paths will cause errors because Bourne shell does not do (~
) character expansions.One approach to avoiding these incompatibilities is to make all commands in ~/.shrc and ~/.profile Bourne shell compatible so TRAMP can complete connections to that remote. To accommodate using non-Bourne shells on that remote, use other shell-specific config files. For example, bash can use ~/.bash_profile and ignore .profile.
- Interactive shell prompt
-
TRAMP redefines the remote shell prompt internally for robust parsing. This redefinition affects the looks of a prompt in an interactive remote shell through commands, such as M-x shell RET. Such prompts, however, can be reset to something more readable and recognizable using these environment variables.
TRAMP sets the
INSIDE_EMACS
environment variable in the startup script file ~/.emacs_SHELLNAME.SHELLNAME
isbash
or equivalent shell names. Change it by setting the environment variableESHELL
in the .emacs as follows:(setenv "ESHELL" "bash")
Then re-set the prompt string in ~/.emacs_SHELLNAME as follows:
# Reset the prompt for remote TRAMP shells. if [ "${INSIDE_EMACS/*tramp*/tramp}" == "tramp" ] ; then PS1="[\u@\h \w]$ " fi
busybox
/nc
¶-
TRAMP’s nc method uses the
nc
command to install and execute a listener as follows (seetramp-methods
):$ nc -l -p 42
The above command-line syntax has changed with
busybox
versions. Ifnc
refuses the ‘-p’ parameter, then overwrite as follows:(add-to-list 'tramp-connection-properties `(,(regexp-quote "192.168.0.1") "remote-copy-args" (("-l") ("%r"))))
where ‘192.168.0.1’ is the remote host IP address (see Setting own connection related information).
Next: FUSE setup hints, Previous: Remote shell setup hints, Up: Configuring TRAMP [Contents][Index]
4.18 Ssh setup hints
The most common TRAMP connection family is based on either
ssh
or scp
of OpenSSH, or plink
or
pscp
of PuTTY on MS Windows. In the following, some
configuration recommendations are given.
- Using ssh config include for host name completion
- Detection of session hangouts
- Using ssh connection sharing
- Configure direct copying between two remote servers
- Issues with Cygwin and MS Windows ssh
4.18.1 Using ssh config include for host name completion
OpenSSH configuration files can use an Include option for further configuration files. Default TRAMP host name completion ignores this option. However, you can configure this yourself.
Given, your ~/.ssh/config file contains the following option:
Include ~/.ssh/conf.d/*
The following code snippet in your .emacs uses all files in that directory for host name completion:
(tramp-set-completion-function "ssh" (append (tramp-get-completion-function "ssh") (mapcar (lambda (file) `(tramp-parse-sconfig ,file)) (directory-files "~/.ssh/conf.d/" 'full directory-files-no-dot-files-regexp))))
This code snippet does it for the ssh method. If you replace "ssh" by "scp", it does it also for that method (or any other method you like).
4.18.2 Detection of session hangouts
ssh
sessions on the local host hang when the network is
down. TRAMP cannot safely detect such hangs. OpenSSH can be
configured to kill such hangs with the following settings in
~/.ssh/config:
Host * ServerAliveInterval 5 ServerAliveCountMax 2
The corresponding PuTTY configuration is in the Connection entry, Seconds between keepalives option. Set this to 5. There is no counter which could be set.
4.18.3 Using ssh connection sharing
TRAMP uses the ControlMaster=auto OpenSSH option by
default, if possible. However, it overwrites ControlPath
settings when initiating ssh
sessions. TRAMP does
this to fend off a stall if a master session opened outside the Emacs
session is no longer open. That is why TRAMP prompts for the
password again even if there is an ssh
already open.
Some OpenSSH versions support a ControlPersist option, which
allows you to set the ControlPath provided the variable
tramp-ssh-controlmaster-options
is customized as follows:
(customize-set-variable 'tramp-ssh-controlmaster-options (concat "-o ControlPath=/tmp/ssh-ControlPath-%%r@%%h:%%p " "-o ControlMaster=auto -o ControlPersist=yes"))
Note how ‘%r’, ‘%h’ and ‘%p’ must be encoded as ‘%%r’, ‘%%h’ and ‘%%p’.
Using a predefined string in tramp-ssh-controlmaster-options
,
or puzzling an own string, happens only when user option
tramp-use-ssh-controlmaster-options
is set to t
. If the
~/.ssh/config file is configured appropriately for the above
behavior, then any changes to ssh
can be suppressed with
this nil
setting:
(customize-set-variable 'tramp-use-ssh-controlmaster-options nil)
Sometimes, it is not possible to use OpenSSH’s ControlMaster
option for remote processes. This could result in concurrent access
to the OpenSSH socket when reading data by different processes, which
could block Emacs. In this case, setting
tramp-use-ssh-controlmaster-options
to suppress
disables
shared access. It is not needed to set this user option permanently
to suppress
, binding the user option prior calling
make-process
is sufficient. TRAMP does this for
esxample for compilation processes on its own.
tramp-use-ssh-controlmaster-options
should also be set to
nil
or suppress
if you use the ProxyCommand or
ProxyJump options in your ssh
configuration.
In order to use the ControlMaster option, TRAMP must
check whether the ssh
client supports this option. This is
only possible on the local host, for the first hop. TRAMP
does not use this option on proxy hosts, therefore.
If you want to use this option also for the other hops, you must configure ~/.ssh/config on the proxy host:
Host * ControlMaster auto ControlPath tramp.%C ControlPersist no
Check the ‘ssh_config(5)’ man page whether these options are supported on your proxy host.
On MS Windows, tramp-use-ssh-controlmaster-options
is set to
nil
by default, because the MS Windows and MSYS2
implementations of OpenSSH
do not support this option properly.
In PuTTY, you can achieve connection sharing in the Connection/SSH entry, enabling the Share SSH connections if possible option.
4.18.4 Configure direct copying between two remote servers
TRAMP uses a temporary local copy when copying two files between different remote hosts via external methods. This behavior is due to authentication problems TRAMP cannot handle sufficiently. However, for scp connections this can be changed. When a file shall be copied between two different remote hosts ‘source’ and ‘target’, and
- - Variable
tramp-use-scp-direct-remote-copying
is non-nil
, - - Remote host ‘source’ doesn’t use the RemoteCommand option in ~/.ssh/config,
- - Remote host ‘target’ shows the same host key when seen from the local host and from host ‘source’, and
- -
scp
running on host ‘source’ can authenticate to host ‘target’ without requiring a password,
TRAMP applies direct remote copying between hosts ‘source’ and ‘target’ like
scp -p -T -R -q -r source:/path/to/file target:/path/to/another/file
This protects also your local temporary directory from overrun when copying large files.
If these conditions do not apply, and
tramp-use-scp-direct-remote-copying
is non-nil
, the
option ‘-3’ is used instead of ‘-R’.
When TRAMP uses direct remote copying, password caches are not consulted.
4.18.5 Issues with Cygwin and MS Windows ssh
This section is incomplete. Please share your solutions.
MS Windows’ ssh
does not open a remote TTY. Use the method
sshx or scpx instead. Furthermore, it cannot read a
passphrase for ssh private keys. Use the MS ssh-agent
.
Cygwin’s ssh
works only with a Cygwin version of Emacs. To
check for compatibility: type M-x eshell RET, and start
ssh test.host RET. Incompatibilities trigger this
message:
Pseudo-terminal will not be allocated because stdin is not a terminal.
Some older versions of Cygwin’s ssh
work with the
sshx access method. Consult Cygwin’s FAQ at
https://cygwin.com/faq/ for details.
On the Emacs
Wiki it is explained how to use the helper program
fakecygpty
to fix this problem.
When using the scpx access method, Emacs may call
scp
with MS Windows file naming, such as c:/foo. But
the version of scp
that is installed with Cygwin does not
know about MS Windows file naming, which causes it to incorrectly look
for a host named ‘c’.
A workaround: write a wrapper script for scp to convert Windows file names to Cygwin file names.
When using the cygwin ssh-agent
on MS Windows for
password-less interaction, ssh methods depend on the
environment variable SSH_AUTH_SOCK
. But this variable is not
set when Emacs is started from a Desktop shortcut and authentication
fails.
One workaround is to use an MS Windows based SSH Agent, such as the
native MS ssh-agent
or Pageant
. The latter is
part of the PuTTY Suite of tools.
The fallback is to start Emacs from a shell.
Next: Android shell setup hints, Previous: Ssh setup hints, Up: Configuring TRAMP [Contents][Index]
4.19 FUSE setup hints
The FUSE file systems are mounted by default at /tmp/tramp.method.user@host#port. The user name and port number are optional. If the file system is already mounted, it will be used as it is. If the mount point does not exist yet, TRAMP creates this directory.
The mount point can be overwritten by the connection property "mount-point", Setting own connection related information. Example:
(add-to-list 'tramp-connection-properties `(,(regexp-quote "/sshfs:user@host:") "mount-point" ,(expand-file-name "sshfs.user@host" user-emacs-directory)))
The user option tramp-fuse-unmount-on-cleanup
, when set to
non-nil
, controls, whether a mount point is unmounted on
connection cleanup or on Emacs exiting.
4.19.1 rclone setup
The default arguments of the rclone
operations
mount
, copyto
, moveto
and
about
are declared in the variable tramp-methods
as
method specific parameters. Usually, they don’t need to be overwritten.
If needed, these parameters can be overwritten as connection properties "mount-args", "copyto-args", "moveto-args" and "about-args", See Setting own connection related information. All of them are list of strings.
Be careful changing "--dir-cache-time", this could delay visibility of files.
4.19.2 sshfs setup
The method sshfs declares the mount arguments in the variable
tramp-methods
, passed to the sshfs
command. This is
a list of list of strings, and can be overwritten by the connection
property "mount-args", See Setting own connection related information.
Additionally, it declares also the arguments for running remote
processes, using the ssh
command. These don’t need to be
changed.
Next: Auto-save, File Lock and Backup configuration, Previous: FUSE setup hints, Up: Configuring TRAMP [Contents][Index]
4.20 Android shell setup hints
TRAMP uses the adb method to access Android devices.
Android devices provide a restricted shell access through an USB
connection. The local host must have the adb
program
installed. Usually, it is sufficient to open the file
/adb::/. Then you can navigate in the file system via
dired
.
Alternatively, applications such as Termux
or SSHDroid
that run sshd
process on the Android device can accept any
ssh-based methods provided these settings are adjusted:
-
sh
must be specified for remote shell since Android devices do not provide/bin/sh
.sh
will then invoke whatever shell is installed on the device with this setting:(add-to-list 'tramp-connection-properties (list (regexp-quote "192.168.0.26") "remote-shell" "sh"))
where ‘192.168.0.26’ is the Android device’s IP address. (see Setting own connection related information).
- On the Android device the directory names are prefixed with an
application specific prefix, which is
/data/data/com.termux/files/usr/bin instead of /usr/bin
in the
Termux
case. You must adapt the file names intramp-remote-path
, for example via connection-local settings:(connection-local-set-profile-variables 'tramp-connection-local-termux-profile `((tramp-remote-path . ,(mapcar (lambda (x) (if (stringp x) (concat "/data/data/com.termux/files" x) x)) (copy-tree tramp-remote-path))))) (connection-local-set-profiles '(:application tramp :machine "192.168.0.26") 'tramp-connection-local-termux-profile)
- When the Android device is not ‘rooted’, specify a writable
directory for temporary files:
(add-to-list 'tramp-connection-properties (list (regexp-quote "192.168.0.26") "tmpdir" "/data/data/com.termux/files/home/tmp"))
- Open a remote connection with the command C-x C-f
/ssh:192.168.0.26#2222: RET, where
sshd
is listening on port ‘2222’.To add a corresponding entry to the ~/.ssh/config file (recommended), use this:
Host android HostName 192.168.0.26 User root Port 2222
To use the host name ‘android’ instead of the IP address shown in the previous example, fix the connection properties as follows:
(add-to-list 'tramp-connection-properties (list (regexp-quote "android") "remote-shell" "sh")) (add-to-list 'tramp-connection-properties (list (regexp-quote "android") "tmpdir" "/data/data/com.termux/files/home/tmp")) (connection-local-set-profiles '(:application tramp :machine "android") 'tramp-connection-local-termux-profile)
Open a remote connection with the more concise command C-x C-f /ssh:android: RET.
Next: Protect remote files by encryption, Previous: Android shell setup hints, Up: Configuring TRAMP [Contents][Index]
4.21 Auto-save, File Lock and Backup configuration
To avoid TRAMP from saving backup files owned by ‘root’
to locations accessible to others, default backup settings in
backup-directory-alist
have to be altered.
Here’s a scenario where files could be inadvertently exposed. Emacs by default writes backup files to the same directory as the original files unless changed to another location, such as ~/.emacs.d/backups/. Such a directory will also be used by default by TRAMP when using, say, a restricted file /su:root@localhost:/etc/secretfile. The backup file of the secretfile is now owned by the user logged in from TRAMP and not ‘root’.
When backup-directory-alist
is nil
(the default), such
problems do not occur.
To “turn off” the backup feature for remote files and stop TRAMP from saving to the backup directory, use this:
(add-to-list 'backup-directory-alist (cons tramp-file-name-regexp nil))
Disabling backups can be targeted to just the su and sudo methods:
(setq backup-enable-predicate (lambda (name) (and (normal-backup-enable-predicate name) (not (let ((method (file-remote-p name 'method))) (when (stringp method) (member method '("su" "sudo"))))))))
Another option is to create better backup file naming with user and
host names prefixed to the file name. For example, transforming
/etc/secretfile to
~/.emacs.d/backups/!su:root@localhost:!etc!secretfile, set the
TRAMP user option tramp-backup-directory-alist
from
the existing user option backup-directory-alist
.
Then TRAMP backs up to a file name that is transformed with a prefix consisting of the DIRECTORY name. This file name prefixing happens only when the DIRECTORY is an absolute local file name.
Example:
(add-to-list 'backup-directory-alist (cons "." "~/.emacs.d/backups/")) (customize-set-variable 'tramp-backup-directory-alist backup-directory-alist)
The backup file name of /su:root@localhost:/etc/secretfile would be /su:root@localhost:~/.emacs.d/backups/!su:root@localhost:!etc!secretfile~.
Just as for backup files, similar issues of file naming affect
auto-saving remote files. Auto-saved files are saved in the directory
specified by the user option auto-save-file-name-transforms
.
By default this is set to the local temporary directory. But in some
versions of Debian GNU/Linux, this points to the source directory
where the Emacs was compiled. Reset such values to a valid directory.
Set auto-save-file-name-transforms
to nil
to save
auto-saved files to the same directory as the original file.
Alternatively, set the user option tramp-auto-save-directory
to direct all auto saves to that location.
An alternative to auto-save-mode
is
auto-save-visited-mode
. In this mode, auto-saving is identical
to explicit saving. If you want to disable this behavior for remote
files, set user option
remote-file-name-inhibit-auto-save-visited
to non-nil
.
And still more issues to handle. Since Emacs 28, file locks use a
similar user option as auto-save files, called
lock-file-name-transforms
. By default this user option is
nil
, meaning to keep file locks in the same directory as the
original file.
If you change lock-file-name-transforms
in order to keep file
locks for remote files somewhere else, you will lose Emacs’s feature
to warn you, if a file is changed in parallel from different Emacs
sessions, or via different remote connections. Be careful with such
settings.
Setting remote-file-name-inhibit-locks
to non-nil
prevents the creation of remote lock files at all.
Per default, TRAMP asks for confirmation if a
‘root’-owned remote backup, auto-save or lock file has to be
written to your local temporary directory. If you want to suppress
this confirmation question, set user option
tramp-allow-unsafe-temporary-files
to t
.
Previous: Auto-save, File Lock and Backup configuration, Up: Configuring TRAMP [Contents][Index]
4.22 Protect remote files by encryption
Note: File encryption in TRAMP is experimental, don’t use it in production systems!
Sometimes, it is desirable to protect files located on remote directories, like cloud storages. In order to do this, you might instruct TRAMP to encrypt all files copied to a given remote directory, and to decrypt such files when accessing. This includes both file contents and file names.
TRAMP does this transparently. Although both files and file names are encrypted on the remote side, they are accessible inside Emacs as they wouldn’t be transformed as such.
Internally, TRAMP uses the encfs
package.
Therefore, this feature is available only if this package is installed
on the local host. TRAMP does not keep and ‘encfs
mountpoint’ permanently. Instead, it encrypts / decrypts files and
file names on the fly, using encfsctl
.
- Command: tramp-crypt-add-directory name ¶
This command marks the existing remote directory name for encryption. Files in that directory and all subdirectories will be encrypted before copying to, and decrypted after copying from that directory. File and directory names will be also encrypted.
- User Option: tramp-crypt-encfs-option ¶
If a remote directory is marked for encryption, it is initialized via
encfs
the very first time a file in this directory is accessed. This user option controls, which defaultencfs
configuration option will be selected, it can be "--standard" or "--paranoia". See the ‘encfs(1)’ man page for details.However, TRAMP must adapt these configuration sets. The
chainedNameIV
configuration option must be disabled; otherwise TRAMP couldn’t handle file name encryption transparently.
A password protected encfs configuration file is created the
very first time you access an encrypted remote directory. It is kept
in your user-emacs-directory
with the url-encoded directory
name as part of the basename, and encfs6.xml as suffix. If
you, for example, mark the remote directory
/nextcloud:user@host:/path/to/dir for encryption, the
configuration file is saved as
tramp-%2Fnextcloud%3Auser%40host%3A%2Fpath%2Fto%2Fdir%2F.encfs6.xml
in user-emacs-directory
. Do not lose this file and the
corresponding password; otherwise there is no way to decrypt your
encrypted files.
- User Option: tramp-crypt-save-encfs-config-remote ¶
If this user option is non-
nil
(the default), the encfs configuration file .encfs6.xml is also kept in the encrypted remote directory. It depends on you, whether you regard the password protection of this file as sufficient. The advantage would be, that such a remote directory could be accessed by different Emacs sessions, different users, without presharing the configuration file between the users.
The command encfsctl
, the workhorse for encryption /
decryption, needs the configuration file password every call.
Therefore, it is recommend to cache this password in Emacs. This can
be done using auth-sources
, Using an authentication file.
An entry needs the url-encoded directory name as machine, your local
user name as user, and the password. The port is optional, if given
it must be the string "crypt". The example above would require
the following entry in the authentication file ("yourname" is the
result of (user-login-name)
):
machine %2Fnextcloud%3Auser%40host%3A%2Fpath%2Fto%2Fdir%2F \ login yourname port crypt password geheim
If you use a remote file name with a quoted localname part, this localname and the corresponding file will not be encrypted / decrypted. If you have an encrypted remote directory /nextcloud:user@host:/path/to/dir, the command
C-x d /nextcloud:user@host:/path/to/dir
will show the directory listing with the plain file names, and the command
C-x d /nextcloud:user@host:/:/path/to/dir
will show the directory listing with the encrypted file names, and visiting a file will show its encrypted contents. However, it is highly discouraged to mix encrypted and not encrypted files in the same directory.
- Command: tramp-crypt-remove-directory name ¶
This command should be used to indicate that files in
name
should no longer be encrypted. Existing encrypted files and subdirectories will remain encrypted.
Next: Reporting Bugs and Problems, Previous: Configuring TRAMP, Up: TRAMP 2.6.3 User Manual [Contents][Index]
5 Using TRAMP
TRAMP operates transparently, accessing remote files as if they are local. However, TRAMP employs a formalized remote file naming syntax to perform its functions transparently. This syntax consists of many parts specifying access methods, authentication, host names, and file names. Ange FTP uses a similar syntax.
Unlike opening local files in Emacs, which are instantaneous, opening remote files in TRAMP is slower at first. Sometimes there is a noticeable delay before the prompts for passwords or authentication appear in the minibuffer. Hitting RET or other keys during this gap will be processed by Emacs. This type-ahead facility is a feature of Emacs that may cause missed prompts when using TRAMP.
- TRAMP file name conventions
- Alternative file name syntax
- File name completion
- Declaring multiple hops in the file name
- Expanding ~ to home directory
- Integration with other Emacs packages
- Cleanup remote connections
- Renaming remote files
- Archive file names
Next: Alternative file name syntax, Up: Using TRAMP [Contents][Index]
5.1 TRAMP file name conventions
/method:host:/path/to/file opens file /path/to/file on the remote host host, using the method method.
- /ssh:melancholia:.emacs
For the file .emacs located in the home directory, on the host
melancholia
, using methodssh
.- /ssh:melancholia.danann.net:.emacs
For the file .emacs specified using the fully qualified domain name of the host.
- /ssh:melancholia:~/.emacs
For the file .emacs specified using the ~, which is expanded.
- /ssh:melancholia:~daniel/.emacs
For the file .emacs located in
daniel
’s home directory on the host,melancholia
. The ~<user> construct is expanded to the home directory of that user on the remote host.- /ssh:melancholia:/etc/squid.conf
For the file /etc/squid.conf on the host
melancholia
.
host can take IPv4 or IPv6 address, as in /ssh:127.0.0.1:.emacs or /ssh:[::1]:.emacs. For syntactical reasons, IPv6 addresses must be embedded in square brackets [ and ].
By default, TRAMP will use the current local user name as the remote user name for log in to the remote host. Specifying a different name using the proper syntax will override this default behavior: /method:user@host:path/to/file.
/ssh:daniel@melancholia:.emacs is for file
.emacs in daniel
’s home directory on the host,
melancholia
, accessing via method ssh
.
For specifying port numbers, affix #<port> to the host name. For example: /ssh:daniel@melancholia#42:.emacs.
All method, user name, host name, port number and local name parts are optional, See Selecting a default method, See Selecting a default user, See Selecting a default host. For syntactical reasons, the default method must be indicated by the pseudo method -.
Next: File name completion, Previous: TRAMP file name conventions, Up: Using TRAMP [Contents][Index]
5.2 Alternative file name syntax
The syntax described in TRAMP file name conventions is the default
syntax, which is active after Emacs startup. However, this can be
changed.
- Command: tramp-change-syntax syntax ¶
This command changes the syntax TRAMP uses for remote file names. Beside the
default
value, syntax can be-
simplified
This remote file name syntax is similar to the syntax used by Ange FTP. A remote file name has the form
/user@host:path/to/file
. Theuser@
part is optional, and the method is determined by Selecting a default method. -
separate
This remote file name syntax originated in the XEmacs text editor. A remote file name has the form
/[method/user@host]path/to/file
. Themethod
anduser@
parts are optional.
-
- Variable: tramp-file-name-regexp ¶
This variable keeps a regexp which matches the selected remote file name syntax. Its value changes after every call of
tramp-change-syntax
. However, it is not recommended to use this variable in external packages, a call offile-remote-p
is much more appropriate.
Next: Declaring multiple hops in the file name, Previous: Alternative file name syntax, Up: Using TRAMP [Contents][Index]
5.3 File name completion
TRAMP can complete the following TRAMP file name components: method names, user names, host names, and file names located on remote hosts.
For example, type C-x C-f / s TAB, TRAMP completion choices show up as
sbin/ | scp: | scpx: | sftp: | sg: |
smb: | srv/ | ssh: | sshx: | su: |
sudo: | sys/ |
‘ssh:’ is a possible completion for the respective method, and ‘sbin/’ stands for the directory /sbin on your local host.
Type s h : for the minibuffer completion to ‘/ssh:’. Typing TAB shows host names TRAMP extracts from ~/.ssh/config file, for example:
ssh:127.0.0.1: | ssh:192.168.0.1: |
ssh:[::1]: | ssh:localhost: |
ssh:melancholia.danann.net: | ssh:melancholia: |
Choose a host from the above list and then continue to complete file names on that host.
When the configuration (see Selecting config files for user/host name completion) includes user names, then the completion lists will account for the user names as well.
Results from auth-sources
search (see Using an authentication file) are added to the completion candidates. This
search could be annoying, for example due to a passphrase request of
the ~/.authinfo.gpg authentication file. The user option
tramp-completion-use-auth-sources
controls, whether such a
search is performed during completion.
Remote hosts previously visited or hosts whose connections are kept
persistently (see Reusing connection related information) will be included in the
completion lists. If you want to suppress this completion because
there are invalid entries in the persistency file, for example if the
host configuration changes often, or if you plug your laptop to
different networks frequently, you can set the user option
tramp-completion-use-cache
to nil
.
After remote host name completion comes completion of file names on the remote host. It works the same as with local host file completion except that killing with double-slash // kills only the file name part of the TRAMP file name syntax. A triple-slash stands for the default behavior.
Example:
C-x C-f /ssh:melancholia:/usr/local/bin//etc TAB -| /ssh:melancholia:/etc C-x C-f /ssh:melancholia://etc TAB -| /ssh:melancholia:/etc C-x C-f /ssh:melancholia:/usr/local/bin///etc TAB -| /etc
Next: Expanding ~ to home directory, Previous: File name completion, Up: Using TRAMP [Contents][Index]
5.4 Declaring multiple hops in the file name
TRAMP file name syntax can accommodate ad-hoc specification of
multiple proxies without using tramp-default-proxies-alist
configuration setup (see Connecting to a remote host using multiple hops).
Each proxy is specified using the same syntax as the remote host specification minus the file name part. Each hop is separated by a ‘|’. Chain the proxies from the starting host to the destination remote host name and file name. For example, hopping over a single proxy ‘bird@bastion’ to a remote file on ‘you@remotehost’:
C-x C-f /ssh:bird@bastion|ssh:you@remotehost:/path RET
Each involved method must be an inline method (see Inline methods).
TRAMP adds the ad-hoc definitions on the fly to
tramp-default-proxies-alist
and is available for reuse during
that Emacs session. Subsequent TRAMP connections to the same
remote host can then use the shortcut form:
‘/ssh:you@remotehost:/path’.
- User Option: tramp-show-ad-hoc-proxies ¶
If this user option is non-
nil
, ad-hoc definitions are kept in remote file names instead of showing the shortcuts.(customize-set-variable 'tramp-show-ad-hoc-proxies t)
Ad-hoc definitions are removed from tramp-default-proxies-alist
via the command M-x tramp-cleanup-all-connections RET
(see Cleanup remote connections).
- User Option: tramp-save-ad-hoc-proxies ¶
For ad-hoc definitions to be saved automatically in
tramp-default-proxies-alist
for future Emacs sessions, settramp-save-ad-hoc-proxies
to non-nil
.(customize-set-variable 'tramp-save-ad-hoc-proxies t)
Ad-hoc proxies can take patterns %h
or %u
like in
tramp-default-proxies-alist
. The following file name expands
to user ‘root’ on host ‘remotehost’, starting with an
ssh session on host ‘remotehost’:
‘/ssh:%h|su:remotehost:’.
On the other hand, if a trailing hop does not specify a host name, the host name of the previous hop is reused. Therefore, the following file name is equivalent to the previous example: ‘/ssh:remotehost|su::’.
Next: Integration with other Emacs packages, Previous: Declaring multiple hops in the file name, Up: Using TRAMP [Contents][Index]
5.5 Expanding ~ to home directory
Home directories on remote hosts can be typed as tilde ~. If possible, they are expanded to the remote user’s home directory on the remote host. Example:
/ssh:user@host:~ ⇒ /ssh:user@host:/home/user
This works in general for ssh-like methods, and for sudoedit. These methods allow also the home directory expansion for another user, like
/sudoedit::~otheruser ⇒ /sudoedit:root@localhost:/home/otheruser
For other methods, a home directory can be expanded only if supported. This happens for example for the sftp method. Methods, which require a share directory in the remote file name (afp, smb), use the value of this share directory as home directory:
/smb:user@host:~ ⇒ /smb:user@host:/share
Since TRAMP cannot know in advance which share directory is intended to use, this expansion can be applied only when a share directory has been used already.
The methods adb, rclone and sshfs do not support home directory expansion at all. However, TRAMP keeps the home directory in the cache. Therefore, those methods could be configured to expand a home directory via a connection property, See Setting own connection related information. Example:
(add-to-list 'tramp-connection-properties (list (regexp-quote "/sshfs:user@randomhost.your.domain:") "~user" "/home/user"))
When your remote file name does not contain a ‘user’ part, the connection property "~" must be used instead.
Next: Cleanup remote connections, Previous: Expanding ~ to home directory, Up: Using TRAMP [Contents][Index]
5.6 Integration with other Emacs packages
TRAMP supports starting new running processes on the remote host for discovering remote file names. Emacs packages on the remote host need no specific modifications for TRAMP’s use.
This type of integration does not work with the ftp method,
and does not support the pty association as specified in
start-file-process
.
process-file
and start-file-process
work on the remote
host when the variable default-directory
is remote:
(let ((default-directory "/ssh:remote.host:")) (start-file-process "grep" (get-buffer-create "*grep*") "/bin/sh" "-c" "grep -e tramp *"))
For a local process, process-file
returns either the exit code
of the process, or a string describing a signal, when the process has
been interrupted. Since it cannot be determined reliably whether a
remote process has been interrupted, process-file
will always
returns the exit code for it. When the user option
process-file-return-signal-string
is non-nil
,
process-file
treats all exit codes greater than 128 as an
indication that the process has been interrupted, and returns a
corresponding string.
This remote process handling does not apply to GVFS
(see GVFS-based external methods) because the remote file system is mounted
on the local host and TRAMP accesses it by changing the
default-directory
.
TRAMP starts a remote process when a command is executed in a
remote file or directory buffer. As of now, these packages have been
integrated to work with TRAMP: shell.el,
eshell.el, compile.el (commands like compile
and
grep
) and gud.el (gdb
or perldb
).
TRAMP always modifies the INSIDE_EMACS
environment
variable for remote processes. By default, this environment variable
shows the Emacs version. TRAMP adds its own version string,
so it looks like ‘27.2,tramp:2.4.5.1’. However, other packages
might also add their name to this environment variable, like
‘27.2,comint,tramp:2.4.5.1’.
For TRAMP to find the command on the remote, it must be
accessible through the default search path as setup by TRAMP
upon first connection. Alternatively, use an absolute path or extend
tramp-remote-path
(see How TRAMP finds and uses programs on the remote host):
(add-to-list 'tramp-remote-path "~/bin") (add-to-list 'tramp-remote-path "/appli/pub/bin")
Customize user option tramp-remote-process-environment
to
suit the remote program’s environment for the remote host.
tramp-remote-process-environment
is a list of strings
structured similar to process-environment
, where each element
is a string of the form ‘ENVVARNAME=VALUE’.
To avoid any conflicts with local host environment variables set through local configuration files, such as ~/.profile, use ‘ENVVARNAME=’ to unset them for the remote environment.
Use add-to-list
to add entries:
(add-to-list 'tramp-remote-process-environment "JAVA_HOME=/opt/java")
Modifying or deleting already existing values in the
tramp-remote-process-environment
list may not be feasible on
restricted remote hosts. For example, some system administrators
disallow changing HISTORY
environment variable. To accommodate
such restrictions when using TRAMP, fix the
tramp-remote-process-environment
by the following code in the
local .emacs file:
(let ((process-environment tramp-remote-process-environment)) (setenv "HISTORY" nil) (setq tramp-remote-process-environment process-environment))
Setting the ENV
environment variable instructs some shells to
read an initialization file. By default, TRAMP disables
this. You can override this behavior by evaluating
(let ((process-environment tramp-remote-process-environment)) (setenv "ENV" "$HOME/.profile") (setq tramp-remote-process-environment process-environment))
In addition to tramp-remote-process-environment
, you can set
environment variables for individual remote process calls by
let-binding process-environment
. TRAMP applies any
entries not present in the global default value of
process-environment
(overriding
tramp-remote-process-environment
settings, if they conflict).
For example:
(let ((process-environment (cons "HGPLAIN=1" process-environment))) (process-file …))
Let-binding in this way works regardless of whether the process to be
called is local or remote, since TRAMP would add just the
HGPLAIN
setting and local processes would take whole value of
process-environment
along with the new value of HGPLAIN
.
For integrating other Emacs packages so TRAMP can execute remotely, please file a bug report. See Reporting Bugs and Problems.
- Running remote programs that create local X11 windows
- Running
shell
on a remote host - Running
shell-command
on a remote host - Running
eshell
on a remote host - Running a debugger on a remote host
- Running remote processes on MS Windows hosts
- Remote process connection type
- Process properties of asynchronous remote processes
- Improving performance of asynchronous remote processes
5.6.1 Running remote programs that create local X11 windows
To allow a remote program to create an X11 window on the local host,
set the DISPLAY
environment variable for the remote host as
follows in the local .emacs file:
(add-to-list 'tramp-remote-process-environment (format "DISPLAY=%s" (getenv "DISPLAY")))
(getenv "DISPLAY")
should return a recognizable name for the
local host that the remote host can redirect X11 window
interactions. If querying for a recognizable name is not possible for
whatever reason, then replace (getenv "DISPLAY")
with a
hard-coded, fixed name. Note that using :0
for X11 display name
here will not work as expected.
An alternate approach is specify ForwardX11 yes or ForwardX11Trusted yes in ~/.ssh/config on the local host.
5.6.2 Running shell
on a remote host
Set explicit-shell-file-name
to the appropriate shell name
when using TRAMP between two hosts with different operating
systems, such as ‘windows-nt’ and ‘gnu/linux’. This option
ensures the correct name of the remote shell program.
When explicit-shell-file-name
is equal to nil
, calling
shell
interactively will prompt for a shell name.
You could use connection-local variables for setting different values
of explicit-shell-file-name
for different remote hosts.
(connection-local-set-profile-variables 'remote-bash '((explicit-shell-file-name . "/bin/bash") (explicit-bash-args . ("-i"))))
(connection-local-set-profile-variables 'remote-ksh '((explicit-shell-file-name . "/bin/ksh") (explicit-ksh-args . ("-i"))))
(connection-local-set-profiles '(:application tramp :protocol "ssh" :machine "localhost") 'remote-bash)
(connection-local-set-profiles `(:application tramp :protocol "sudo" :user "root" :machine ,(system-name)) 'remote-ksh)
5.6.3 Running shell-command
on a remote host
shell-command
executes commands synchronously or asynchronously
on remote hosts and displays output in buffers on the local
host. Example:
C-x C-f /sudo:: RET M-& tail -f /var/log/syslog.log RET
tail
command outputs continuously to the local buffer whose
name is the value of the variable shell-command-buffer-name-async
.
M-x auto-revert-tail-mode RET runs similarly showing continuous output.
shell-command
uses the user option shell-file-name
and
the variable shell-command-switch
in order to determine which
shell to run. For remote hosts, their default values are
/bin/sh and -c, respectively (except for the
adb method, which uses /system/bin/sh). Like the
variables in the previous section, these variables can be changed via
connection-local variables.
If Emacs supports the user option async-shell-command-width
(since Emacs 27), TRAMP cares about its value for
asynchronous shell commands. It specifies the number of display
columns for command output. For synchronous shell commands, a similar
effect can be achieved by adding the environment variable
COLUMNS
to tramp-remote-process-environment
.
5.6.4 Running eshell
on a remote host
TRAMP is integrated into eshell.el, which enables
interactive eshell sessions on remote hosts at the command prompt.
You must add the module eshell-tramp
to
eshell-modules-list
. Here’s a sample interaction after opening
M-x eshell RET on a remote host:
~ $ cd /sudo::/etc RET /sudo:root@host:/etc $ hostname RET host /sudo:root@host:/etc $ id RET uid=0(root) gid=0(root) groups=0(root) /sudo:root@host:/etc $ find-file shadow RET #<buffer shadow> /sudo:root@host:/etc $
eshell
added custom su
and sudo
commands that set
the default directory correctly for the *eshell* buffer.
TRAMP silently updates tramp-default-proxies-alist
with an entry for this directory (see Connecting to a remote host using multiple hops):
~ $ cd /ssh:user@remotehost:/etc RET /ssh:user@remotehost:/etc $ find-file shadow RET File is not readable: /ssh:user@remotehost:/etc/shadow /ssh:user@remotehost:/etc $ sudo find-file shadow RET #<buffer shadow>
/ssh:user@remotehost:/etc $ su - RET /su:root@remotehost:/root $ id RET uid=0(root) gid=0(root) groups=0(root) /su:root@remotehost:/root $
5.6.5 Running a debugger on a remote host
gud.el provides a unified interface to symbolic
debuggers.
TRAMP can run debug on remote hosts by calling gdb
with a remote file name:
M-x gdb RET Run gdb (like this): gdb -i=mi /ssh:host:~/myprog RET
Since the remote gdb
and gdb-inferior
processes do not
belong to the same process group on the remote host, there will be a
warning, which can be ignored:
&"warning: GDB: Failed to set controlling terminal: Operation not permitted\n"
As consequence, there will be restrictions in I/O of the process to be debugged.
Relative file names are based on the remote default directory. When myprog.pl exists in /ssh:host:/home/user, valid calls include:
M-x perldb RET Run perldb (like this): perl -d myprog.pl RET
Just the local part of a remote file name, such as perl -d
/home/user/myprog.pl
, is not possible.
Arguments of the program to be debugged must be literal, can take relative or absolute paths, but not remote paths.
5.6.6 Running remote processes on MS Windows hosts
winexe
runs processes on a remote MS Windows host, and
TRAMP can use it for process-file
and
start-file-process
.
tramp-smb-winexe-program
specifies the local winexe
command. Powershell V2.0 on the remote host is required to run
processes triggered from TRAMP.
explicit-shell-file-name
and explicit-*-args
have to
be set properly so M-x shell RET can open a proper remote
shell on a MS Windows host. To open cmd
, set it as follows:
(setq explicit-shell-file-name "cmd" explicit-cmd-args '("/q"))
To open powershell
as a remote shell, use this:
(setq explicit-shell-file-name "powershell" explicit-powershell-args '("-file" "-"))
5.6.7 Remote process connection type
Asynchronous processes behave differently based on whether they use a
pseudo tty or not. This is controlled by the variable
process-connection-type
, which can be t
or pty
(use a pseudo tty), or nil
or pipe
(don’t use one).
TRAMP is based on running shells on the remote host, which
requires a pseudo tty. Therefore, it declares the variable
tramp-process-connection-type
, which carries this information
for remote processes. Its default value is t
, and there is no
need to change it. The name of the remote pseudo tty is returned by
the function process-tty-name
.
If a remote process, started by start-file-process
, should
not use a pseudo tty, this can be requested by setting
process-connection-type
to nil
or pipe
. There is
still a pseudo tty for the started process, but some terminal
properties are changed, like suppressing translation of carriage
return characters into newline.
The function make-process
allows controlling this explicitly by
using the :connection-type
keyword. If this keyword is not
used, the value of process-connection-type
is applied instead.
5.6.8 Process properties of asynchronous remote processes
When available, TRAMP adds process properties to process objects of asynchronous properties. However, it is not guaranteed that all these properties are set.
-
remote-tty
This is the name of the terminal a process uses on the remote host, i.e., it reads and writes on.
-
remote-pid
The process id of the command executed on the remote host. This is used when sending signals remotely.
-
remote-command
The remote command which has been invoked via
make-process
orstart-file-process
, a list of strings (program and its arguments). This does not show the additional shell sugar TRAMP makes around the commands, in order to see this you must inspect TRAMP traces.
The functions list-system-processes
and
process-attributes
return information about system processes on
the respective remote host. In order to retrieve this information,
they use the command ps
, driven by the following constants:
- Constant: tramp-process-attributes-ps-args ¶
This is a list of arguments (strings)
ps
is called with. The default value is appropriate for GNU/Linux remote hosts.
- Constant: tramp-process-attributes-ps-format ¶
This is a list of cons cells
(key . type)
for interpretation of theps
output. key is a key used in theprocess-attributes
output plus the keypid
, and type is the respective value returned byps
. It can be• numberp
— a number • stringp
— a string without spaces • number — a string of number width, could contain spaces • nil
— a string until end of line The default value is appropriate for GNU/Linux remote hosts.
If, for example, tramp-process-attributes-ps-args
is declared
as ("-eww" "-o" "pid,euid,euser,egid,egroup,comm:40,state")
,
the output of the respective ps
command would look like
PID EUID EUSER EGID EGROUP COMMAND S 1 0 root 0 root systemd S 1610 0 root 0 root NFSv4 callback S …
The corresponding tramp-process-attributes-ps-format
has the value
((pid . numberp) (euid . numberp) (user . stringp)
(egid . numberp) (group . stringp) (comm . 40) (state . stringp))
The default values for tramp-process-attributes-ps-args
and
tramp-process-attributes-ps-format
can be overwritten by
connection-local variables.
This is already done by TRAMP for the adb method, see
tramp-adb-connection-local-default-ps-profile
and
tramp-adb-connection-local-default-ps-variables
.
There are three further predefined sets of connection-local variables
for remote BSD systems, for remote macOS systems, and for a remote
ps
command implemented with busybox
. These are
called tramp-connection-local-*-ps-profile
and
tramp-connection-local-*-ps-variables
. Use them like
(connection-local-set-profiles '(:application tramp :machine "mybsdhost") 'tramp-connection-local-bsd-ps-profile)
If you want to see a listing of remote system processes when calling
proced
, set user option proced-show-remote-processes
to
non-nil
, or invoke that command with a negative argument like
C-u - M-x proced RET when your buffer has a remote
default-directory
.
5.6.9 Improving performance of asynchronous remote processes
TRAMP’s implementation of make-process
and
start-file-process
requires a serious overhead for
initialization, every process invocation. This is needed for handling
interactive dialogs when connecting the remote host (like providing
a password), and initial environment setup.
Sometimes, this is not needed. Instead of starting a remote shell and
running the command afterwards, it is sufficient to run the command
directly. TRAMP supports this by an alternative
implementation of make-process
and start-file-process
.
This is triggered by the connection property
"direct-async-process", See Setting own connection related information,
which must be set to a non-nil
value. Example:
(add-to-list 'tramp-connection-properties (list (regexp-quote "/ssh:user@host:") "direct-async-process" t))
Using direct asynchronous processes in TRAMP is not possible, if the remote host is connected via multiple hops (see Connecting to a remote host using multiple hops). In this case, TRAMP falls back to its classical implementation.
Furthermore, this approach has the following limitations:
- It works only for some connection methods defined in tramp-adb.el, tramp-container.el, tramp-sh.el and tramp-sshfs.el.
- It does not support interactive user authentication. With
ssh-based methods, this can be avoided by using a password
agent like
ssh-agent
, using public key authentication, or using ControlMaster options. - It cannot be applied for ssh-based methods, which use the RemoteCommand option.
- It cannot be killed via
interrupt-process
. - It does not report the remote terminal name via
process-tty-name
. - It does not set process property
remote-pid
. - It does not use
tramp-remote-path
.
In order to gain even more performance, it is recommended to bind
tramp-verbose
to 0 when running make-process
or
start-file-process
. Furthermore, you might set
tramp-use-ssh-controlmaster-options
to nil
in order to
bypass TRAMP’s handling of the ControlMaster options,
and use your own settings in ~/.ssh/config, Using ssh connection sharing.
Next: Renaming remote files, Previous: Integration with other Emacs packages, Up: Using TRAMP [Contents][Index]
5.7 Cleanup remote connections
TRAMP provides several ways to flush remote connections.
- Command: tramp-cleanup-connection vec &optional keep-debug keep-password ¶
This command flushes all connection related objects. vec is the internal representation of a remote connection. When called interactively, this command lists active remote connections in the minibuffer. Each connection is of the format /method:user@host:.
Flushing remote connections also cleans the password cache (see Reusing passwords for several connections), file cache, connection cache (see Reusing connection related information), and recentf cache. It also deletes session timers (see Setting own connection related information) and connection buffers.
If keep-debug is non-
nil
, the debug buffer is kept. A non-nil
keep-password preserves the password cache.
- Command: tramp-cleanup-this-connection ¶
Flushes the current buffer’s remote connection objects, the same as in
tramp-cleanup-connection
.
- Command: tramp-cleanup-all-connections ¶
Flushes all active remote connection objects, the same as in
tramp-cleanup-connection
. This command removes also ad-hoc proxy definitions (see Declaring multiple hops in the file name).
- Command: tramp-cleanup-all-buffers ¶
Just as for
tramp-cleanup-all-connections
, all remote connections and ad-hoc proxy definition are cleaned up in addition to killing all buffers related to remote connections.
Next: Archive file names, Previous: Cleanup remote connections, Up: Using TRAMP [Contents][Index]
5.8 Renaming remote files
Sometimes, it is desirable to safe file contents of buffers visiting a given remote host. This could happen for example, if the local host changes its network integration, and the remote host is not reachable anymore.
- Command: tramp-rename-files source target ¶
Replace in all buffers the visiting file name from source to target. source is a remote directory name, which could contain also a localname part. target is the directory name source is replaced with. Often, target is a remote directory name on another host, but it can also be a local directory name. If target has no local part, the local part from source is used.
If target is
nil
, it is selected according to the first match intramp-default-rename-alist
. If called interactively, this match is offered as initial value for selection.On all buffers, which have a
buffer-file-name
matching source, this name is modified by replacing source with target. This is applied by callingset-visited-file-name
. The newbuffer-file-name
is prompted for modification in the minibuffer. The buffers are marked modified, and must be saved explicitly.If user option
tramp-confirm-rename-file-names
isnil
, changing the file name happens without confirmation. This requires a matching entry intramp-default-rename-alist
.Remote buffers related to the remote connection identified by source, which are not visiting files, or which are visiting files not matching source, are not modified.
Interactively, target is selected from
tramp-default-rename-alist
without confirmation if the prefix argument is non-nil
.The remote connection identified by source is flushed by
tramp-cleanup-connection
.
- Command: tramp-rename-these-files target ¶
Replace visiting file names to target. The current buffer must be related to a remote connection. In all buffers, which are visiting a file with the same directory name, the buffer file name is changed.
Interactively, target is selected from
tramp-default-rename-alist
without confirmation if the prefix argument is non-nil
.
- User Option: tramp-default-rename-alist ¶
The default target for renaming remote buffer file names. This is an alist of cons cells
(source . target)
. The first matching item specifies the target to be applied for renaming buffer file names from source viatramp-rename-files
.source
is a regular expressions, which matches a remote file name.target
must be a directory name, which could be remote (including remote directories TRAMP infers by default, such as ‘/method:user@host:’).target
can contain the patterns%m
,%u
or%h
, which are replaced by the method name, user name or host name ofsource
when callingtramp-rename-files
.source
could also be a Lisp form, which will be evaluated. The result must be a string ornil
, which is interpreted as a regular expression which always matches.Example entries:
("/ssh:badhost:/path/to/dir/" . "/ssh:goodhost:/path/to/another/dir/")
would trigger renaming of buffer file names on ‘badhost’ to ‘goodhost’, including changing the directory name.
("/ssh:.+\\.company\\.org:" . "/ssh:multi.hop|ssh:%h:")
routes all connections to a host in ‘company.org’ via ‘/ssh:multi.hop:’, which might be useful when using Emacs outside the company network.
(nil . "~/saved-files/%m:%u@%h/")
saves all remote files locally, with a directory name including method name, user name and host name of the remote connection.
- User Option: tramp-confirm-rename-file-names ¶
Whether renaming a buffer file name by
tramp-rename-files
ortramp-rename-these-files
must be confirmed.
Previous: Renaming remote files, Up: Using TRAMP [Contents][Index]
5.9 Archive file names
TRAMP offers also transparent access to files inside file archives. This is possible only on hosts which have installed GVFS (the GNOME Virtual File System), GVFS-based external methods. Internally, file archives are mounted via the GVFS archive method.
A file archive is a regular file of kind /path/to/dir/file.EXT. The extension ‘.EXT’ identifies the type of the file archive. To examine the contents of an archive with Dired, open file name as if it were a directory (i.e., open /path/to/dir/file.EXT/). A file inside a file archive, called archive file name, has the name /path/to/dir/file.EXT/dir/file.
Most of the (elisp)magic file name operations, are implemented for archive file names, exceptions are all operations which write into a file archive, and process related operations. Therefore, functions like
(copy-file "/path/to/dir/file.tar/dir/file" "/somewhere/else")
work out of the box. This is also true for file name completion, and
for libraries like dired
or ediff
, which accept archive
file names as well.
File archives are identified by the file name extension ‘.EXT’.
Since GVFS uses internally the library libarchive(3)
,
all suffixes, which are accepted by this library, work also for
archive file names. Accepted suffixes are listed in the constant
tramp-archive-suffixes
. They are
- ‘.7z’ — 7-Zip archives
- ‘.apk’ — Android package kits
- ‘.ar’ — UNIX archiver formats
- ‘.cab’, ‘.CAB’ — Microsoft Windows cabinets
- ‘.cpio’ — CPIO archives
- ‘.crate’ — Cargo (Rust) packages
- ‘.deb’ — Debian packages
- ‘.depot’ — HP-UX SD depots
- ‘.epub’ — Electronic publications
- ‘.exe’ — Self extracting Microsoft Windows EXE files
- ‘.iso’ — ISO 9660 images
- ‘.jar’ — Java archives
- ‘.lzh’, ‘.LZH’ — Microsoft Windows compressed LHA archives
- ‘.msu’, ‘.MSU’ — Microsoft Windows Update packages
- ‘.mtree’ — BSD mtree format
- ‘.odb’, ‘.odf’, ‘.odg’, ‘.odp’, ‘.ods’, ‘.odt’ — OpenDocument formats
- ‘.pax’ — Posix archives
- ‘.rar’ — RAR archives
- ‘.rpm’ — Red Hat packages
- ‘.shar’ — Shell archives
- ‘.tar’, ‘.tbz’, ‘.tgz’, ‘.tlz’, ‘.txz’, ‘.tzst’ — (Compressed) tape archives
- ‘.warc’ — Web archives
- ‘.xar’ — macOS XAR archives
- ‘.xpi’ — XPInstall Mozilla addons
- ‘.xps’ — Open XML Paper Specification (OpenXPS) documents
- ‘.zip’, ‘.ZIP’ — ZIP archives
File archives could also be compressed, identified by an additional
compression suffix. Valid compression suffixes are listed in the
constant tramp-archive-compression-suffixes
. They are
‘.bz2’, ‘.gz’, ‘.lrz’, ‘.lz’, ‘.lz4’,
‘.lzma’, ‘.lzo’, ‘.uu’, ‘.xz’, ‘.Z’, and
‘.zst’. A valid archive file name would be
/path/to/dir/file.tar.gz/dir/file. Even several suffixes in a
row are possible, like /path/to/dir/file.tar.gz.uu/dir/file.
An archive file name could be a remote file name, as in
/ftp:anonymous@ftp.gnu.org:/gnu/tramp/tramp-2.4.5.tar.gz/INSTALL.
Since all file operations are mapped internally to GVFS
operations, remote file names supported by tramp-gvfs
perform
better, because no local copy of the file archive must be downloaded
first. For example, ‘/sftp:user@host:...’ performs better than
the similar ‘/scp:user@host:...’. See the constant
tramp-archive-all-gvfs-methods
for a complete list of
tramp-gvfs
supported method names.
If url-handler-mode
is enabled, archives could be visited via
URLs, like
https://ftp.gnu.org/gnu/tramp/tramp-2.4.5.tar.gz/INSTALL. This
allows complex file operations like
(progn (url-handler-mode 1) (ediff-directories "https://ftp.gnu.org/gnu/tramp/tramp-2.4.4.tar.gz/tramp-2.4.4" "https://ftp.gnu.org/gnu/tramp/tramp-2.4.5.tar.gz/tramp-2.4.5" ""))
It is even possible to access file archives in file archives, as
(progn (url-handler-mode 1) (find-file "https://ftp.debian.org/debian/pool/main/c/coreutils/\ coreutils_8.28-1_amd64.deb/control.tar.gz/control"))
In order to disable file archives, you could add the following form to your init file:
(customize-set-variable 'tramp-archive-enabled nil)
Next: Frequently Asked Questions, Previous: Using TRAMP, Up: TRAMP 2.6.3 User Manual [Contents][Index]
6 Reporting Bugs and Problems
TRAMP’s development team is actively engaged in solving bugs and problems and looks to feature requests and suggestions.
TRAMP’s mailing list is the place for more advice and information on working with TRAMP, solving problems, discussing, and general discussions about TRAMP.
TRAMP’s mailing list is moderated but even non-subscribers can post for moderator approval. Sometimes this approval step may take as long as 48 hours due to public holidays.
tramp-devel@gnu.org is the mailing list. Messages sent to this address go to all the subscribers. This is not the address to send subscription requests to.
To subscribe to the mailing list, visit: the TRAMP Mail Subscription Page.
Check if the bug or problem is already addressed in See Frequently Asked Questions.
Run M-x tramp-bug RET to generate a buffer with details of the system along with the details of the TRAMP installation. Please include these details with the bug report.
The bug report must describe in as excruciating detail as possible the steps required to reproduce the problem. These details must include the setup of the remote host and any special or unique conditions that exist.
Include a minimal test case that reproduces the problem. This will help the development team find the best solution and avoid unrelated detours.
To exclude cache-related problems, flush all caches before running the
test, Cleanup remote connections. Alternatively, and often
better for analysis, reproduce the problem in a clean Emacs session
started with emacs -Q
. Then, TRAMP does not load
the persistency file (see Reusing connection related information), and it does not use
passwords from auth-source.el (see Reusing passwords for several connections). The
latter does not happen for the sudoedit method, otherwise it
would be unusable.
If you use the GNU ELPA version of TRAMP, you must load it
explicitly, because emacs -Q
ignores installed ELPA
packages. Call (version number adapted)
$ emacs -Q -l ~/.emacs.d/elpa/tramp-2.4.5.1/tramp-autoloads
When including TRAMP’s messages in the bug report, increase the verbosity level to 6 (see Traces) in the ~/.emacs file before repeating steps to the bug. Include the contents of the *tramp/foo* and *debug tramp/foo* buffers with the bug report. Both buffers could contain non-ASCII characters which are relevant for analysis, append the buffers as attachments to the bug report. This is also needed in order to avoid line breaks during mail transfer.
If you send the message from Emacs, you are asked about to append these buffers to the bug report. If you use an external mail program, you must save these buffers to files, and append them with that mail program.
Note that a verbosity level greater than 6 is not necessary at this stage. Also note that a verbosity level of 6 or greater, the contents of files and directories will be included in the debug buffer. Passwords typed in TRAMP will never be included there.
Next: How file names, directories and localnames are mangled and managed, Previous: Reporting Bugs and Problems, Up: TRAMP 2.6.3 User Manual [Contents][Index]
7 Frequently Asked Questions
- What is the official name - “Tramp” or “TRAMP”?
The official name is “Tramp”. This is used in comments, docstrings, and everywhere speaking about TRAMP.
However, for historical reasons this is formatted as “@sc{Tramp}” in the TRAMP manual. So it looks different there.
- Where is the latest TRAMP?
TRAMP is available at the GNU URL:
https://ftp.gnu.org/gnu/tramp/
TRAMP’s GNU project page is located here:
- Which systems does it work on?
The package works successfully on Emacs 26, Emacs 27, Emacs 28, and Emacs 29.
While Unix and Unix-like systems are the primary remote targets, TRAMP has equal success connecting to other platforms, such as MS Windows 7/8/10.
- How to speed up TRAMP?
TRAMP does many things in the background, some of which depends on network speeds, response speeds of remote hosts, and authentication delays. During these operations, TRAMP’s responsiveness slows down. Some suggestions within the scope of TRAMP’s settings include:
- - Use an external method, such as scp, which are faster than internal methods for large files.
- - Keep the file
tramp-persistency-file-name
, which is where TRAMP caches remote information about hosts and files. Caching is enabled by default. Don’t disable it.Set
remote-file-name-inhibit-cache
tonil
if remote files are not independently updated outside TRAMP’s control. That cache cleanup will be necessary if the remote directories or files are updated independent of TRAMP. - - Disable version control to avoid delays:
(setq vc-ignore-dir-regexp (format "\\(%s\\)\\|\\(%s\\)" vc-ignore-dir-regexp tramp-file-name-regexp))
If this is too radical, because you want to use version control remotely, trim
vc-handled-backends
to just those you care about, for example:(setq vc-handled-backends '(SVN Git))
- -
Disable file locks. Set
remote-file-name-inhibit-locks
tot
if you know that different Emacs sessions are not modifying the same remote file. - - Disable excessive traces. Set
tramp-verbose
to 3 or lower, default being 3. Increase trace levels temporarily when hunting for bugs.
- TRAMP does not connect to the remote host
Three main reasons for why TRAMP does not connect to the remote host:
- - Unknown characters in the prompt
TRAMP needs a clean recognizable prompt on the remote host for accurate parsing. Shell prompts that contain escape sequences for coloring cause parsing problems. Remote shell setup hints for customizing prompt detection using regular expressions.
To check if the remote host’s prompt is being recognized, use this test: switch to TRAMP connection buffer *tramp/foo*, put the cursor at the top of the buffer, and then apply the following expression:
M-: (re-search-forward (concat tramp-shell-prompt-pattern "$")) RET
If the cursor has not moved to the prompt at the bottom of the buffer, then TRAMP has failed to recognize the prompt.
When using zsh on remote hosts, disable zsh line editor because zsh uses left-hand side and right-hand side prompts in parallel. Add the following line to ~/.zshrc:
[[ $TERM == "dumb" ]] && unsetopt zle && PS1='$ ' && return
This uses the default value of
tramp-terminal-type
, "dumb", as value of theTERM
environment variable. If you want to use another value forTERM
, changetramp-terminal-type
and this line accordingly.Alternatively, you could set the remote login shell explicitly. See Remote shell setup hints for discussion of this technique,
When using fish shell on remote hosts, disable fancy formatting by adding the following to ~/.config/fish/config.fish:
function fish_prompt if test $TERM = "dumb" echo "\$ " else … end end
When using WinSSHD on remote hosts, TRAMP does not recognize the strange prompt settings.
A similar problem exist with the iTerm2 shell integration, which sends proprietary escape codes when starting a shell. This can be suppressed by changing the respective integration snippet in your ~/.profile like this:
[ $TERM = "dumb" ] || \ test -e "${HOME}/.iterm2_shell_integration.bash" && \ source "${HOME}/.iterm2_shell_integration.bash"
And finally, bash’s readline should not use key bindings like ‘C-j’ to commands. Disable this in your ~/.inputrc:
$if term=dumb # Don't bind Control-J or it messes up TRAMP. $else "\C-j": next-history $endif
- - Echoed characters after login
TRAMP suppresses echos from remote hosts with the
stty -echo
command. But sometimes it is too late to suppress welcome messages from the remote host containing harmful control characters. Using sshx or scpx methods can avoid this problem because they allocate a pseudo tty. See Inline methods. - - TRAMP stops transferring strings longer than 500 characters
Set
tramp-chunksize
to 500 to get around this problem, which is related to faulty implementation ofprocess-send-string
on HP-UX, FreeBSD and Tru64 Unix systems. Consult the documentation fortramp-chunksize
to see when this is necessary.Set
file-precious-flag
tot
for files accessed by TRAMP so the file contents are checked using checksum by first saving to a temporary file.(add-hook 'find-file-hook (lambda () (when (file-remote-p default-directory) (set (make-local-variable 'file-precious-flag) t))))
- - Unknown characters in the prompt
- TRAMP fails in a chrooted environment
When connecting to a local host, TRAMP uses some internal optimizations. They fail when Emacs runs in a chrooted environment. In order to disable those optimizations, set user option
tramp-local-host-regexp
tonil
. - Does TRAMP support SSH security keys?
Yes.
OpenSSH
has added support for FIDO hardware devices via special key types *-sk. TRAMP supports the additional handshaking messages for them. This requires at leastOpenSSH
8.2, and a FIDO U2F or FIDO2 compatible security key, like yubikey, solokey, nitrokey, or titankey.Note that there are reports on problems of handling FIDO2 (residential) keys by
ssh-agent
. As workaround, you might disablessh-agent
for such keys. - TRAMP does not connect to Samba or MS Windows hosts running
SMB1 connection protocol
Recent versions of
smbclient
do not support old connection protocols by default. In order to connect to such a host, add a respective option:(add-to-list 'tramp-smb-options "client min protocol=NT1")
Note that using a deprecated connection protocol raises security problems, you should do it only if absolutely necessary.
- File name completion does not work with TRAMP
ANSI escape sequences from the remote shell may cause errors in TRAMP’s parsing of remote buffers.
To test if this is the case, open a remote shell and check if the output of
ls
is in color.To disable ANSI escape sequences from the remote hosts, disable ‘--color=yes’ or ‘--color=auto’ in the remote host’s .bashrc or .profile. Turn this alias on and off to see if file name completion works.
- File name completion does not work in directories with large number of
files
This may be related to globbing, which is the use of shell’s ability to expand wild card specifications, such as ‘*.c’. For directories with large number of files, globbing might exceed the shell’s limit on length of command lines and hang. TRAMP uses globbing.
To test if globbing hangs, open a shell on the remote host and then run
ls -d * ..?* > /dev/null
.When testing, ensure the remote shell is the same shell (
/bin/sh
,ksh
orbash
), that TRAMP uses when connecting to that host. - How to get notified after TRAMP completes file transfers?
Make Emacs beep after reading from or writing to the remote host with the following code in ~/.emacs.
(add-hook 'tramp-handle-write-region-hook 'beep) (add-hook 'tramp-handle-file-local-copy-hook 'beep)
- How to get a Visual Warning when working with ‘root’ privileges?
Host indication in the mode line?
Install tramp-theme from GNU ELPA via Emacs’s Package Manager. Enable it via M-x load-theme RET tramp RET. Further customization is explained in user option
tramp-theme-face-remapping-alist
. - Remote host does not understand default options for directory listing
Emacs computes the
dired
options based on the local host but if the remote host cannot understand the samels
command, then set them with a hook as follows:(add-hook 'dired-before-readin-hook (lambda () (when (file-remote-p default-directory) (setq dired-actual-switches "-al"))))
- Why is ~/.sh_history on the remote host growing?
Due to the remote shell saving tilde expansions triggered by TRAMP, the history file is probably growing rapidly. TRAMP can suppress this behavior with the user option
tramp-histfile-override
. When set tot
, environment variableHISTFILE
is unset, and environment variablesHISTFILESIZE
andHISTSIZE
are set to 0. Don’t use this withbash
5.0.0. There is a bug inbash
which letsbash
die.Alternatively,
tramp-histfile-override
could be a string. Environment variableHISTFILE
is set to this file name then. Be careful when setting to /dev/null; this might result in undesired results when usingbash
as remote shell.Another approach is to disable TRAMP’s handling of the
HISTFILE
at all by settingtramp-histfile-override
tonil
. In this case, saving history could be turned off by putting this shell code in .bashrc or .kshrc:if [ -f $HOME/.sh_history ] ; then /bin/rm $HOME/.sh_history fi if [ "${HISTFILE-unset}" != "unset" ] ; then unset HISTFILE fi if [ "${HISTSIZE-unset}" != "unset" ] ; then unset HISTSIZE fi
For ssh-based method, add the following line to your ~/.ssh/environment:
HISTFILE=/dev/null
- Where are remote files trashed to?
Emacs can trash file instead of deleting them. Remote files are always trashed to the local trash, except remote encrypted files (see Protect remote files by encryption), which are deleted anyway.
If Emacs is configured to use the XDG conventions for the trash directory, remote files cannot be restored with the respective tools, because those conventions don’t specify remote paths. Such files must be restored by moving them manually from ${XDG_DATA_HOME}/Trash/files/, if needed.
- How to identify temporary files produced by TRAMP?
Temporary files are kept in your
temporary-file-directory
directory, which is often /tmp/. By default, they have the file name prefix "tramp.". If you want to change this prefix, for example because you want to identify temporary files produced byfile-local-copy
in your package, you can bind the variabletramp-temp-name-prefix
temporarily:(let ((tramp-temp-name-prefix "my-prefix.")) (file-local-copy "/ssh::.emacs")) ⇒ "/tmp/my-prefix.HDfgDZ"
- How to shorten long file names when typing in TRAMP?
Adapt several of these approaches to reduce typing. If the full name is /ssh:news@news.my.domain:/opt/news/etc, then:
- Use simplified syntax:
If you always apply the default method (see Selecting a default method), you could use the simplified TRAMP syntax (see Alternative file name syntax):
(customize-set-variable 'tramp-default-method "ssh") (tramp-change-syntax 'simplified)
The reduced typing: C-x C-f
/news@news.my.domain:/opt/news/etc
RET. - Use default values for method name and user name:
You can define default methods and user names for hosts, (see Selecting a default method, see Selecting a default user):
(custom-set-variables '(tramp-default-method "ssh") '(tramp-default-user "news"))
The reduced typing: C-x C-f /-:news.my.domain:/opt/news/etc RET.
Note that there are some useful shortcuts already. Accessing your local host as ‘root’ user, is possible just by C-x C-f /su:: RET.
- Use configuration options of the access method:
Programs used for access methods already offer powerful configurations (see Selecting config files for user/host name completion). For ssh, configure the file ~/.ssh/config:
Host xy HostName news.my.domain User news
The reduced typing: C-x C-f /ssh:xy:/opt/news/etc RET.
Depending on the number of files in the directories, host names completion can further reduce key strokes: C-x C-f /ssh:x TAB.
- Use environment variables to expand long strings:
For long file names, set up environment variables that are expanded in the minibuffer. Environment variables are set either outside Emacs or inside Emacs with Lisp:
(setenv "xy" "/ssh:news@news.my.domain:/opt/news/etc/")
The reduced typing: C-x C-f $xy RET.
Note that file name cannot be edited here because the environment variables are not expanded during editing in the minibuffer.
- Define own keys:
Redefine another key sequence in Emacs for C-x C-f:
(global-set-key [(control x) (control y)] (lambda () (interactive) (find-file (read-file-name "Find TRAMP file: " "/ssh:news@news.my.domain:/opt/news/etc/"))))
Simply typing C-x C-y would prepare minibuffer editing of file name.
See the Emacs Wiki for a more comprehensive example.
- Define own abbreviation (1):
Abbreviation list expansion can be used to reduce typing long file names:
(add-to-list 'directory-abbrev-alist '("^/xy" . "/ssh:news@news.my.domain:/opt/news/etc/"))
The reduced typing: C-x C-f /xy RET.
Note that file name cannot be edited here because the abbreviations are not expanded during editing in the minibuffer. Furthermore, the abbreviation is not expanded during TAB completion.
- Define own abbreviation (2):
The
abbrev-mode
gives additional flexibility for editing in the minibuffer:(define-abbrev-table 'my-tramp-abbrev-table '(("xy" "/ssh:news@news.my.domain:/opt/news/etc/")))
(add-hook 'minibuffer-setup-hook (lambda () (abbrev-mode 1) (setq local-abbrev-table my-tramp-abbrev-table)))
(advice-add 'minibuffer-complete :before 'expand-abbrev)
The reduced typing: C-x C-f xy TAB.
The minibuffer expands for further editing.
- Use bookmarks:
Use bookmarks to save TRAMP file names.
Upon visiting a location with TRAMP, save it as a bookmark with menu-bar edit bookmarks set.
To revisit that bookmark: menu-bar edit bookmarks jump.
- Use recent files:
recentf remembers visited places.
Keep remote file names in the recent list without have to check for their accessibility through remote access:
(recentf-mode 1)
Reaching recently opened files: menu-bar file Open Recent.
- Use filecache:
Since filecache remembers visited places, add the remote directory to the cache:
(with-eval-after-load 'filecache (file-cache-add-directory "/ssh:news@news.my.domain:/opt/news/etc/"))
Then use directory completion in the minibuffer with C-x C-f C-TAB.
- Use bbdb:
bbdb has a built-in feature for Ange FTP files, which also works for TRAMP file names.
Load bbdb in Emacs:
(require 'bbdb) (bbdb-initialize)
Create a BBDB entry with M-x bbdb-create-ftp-site RET. Then specify a method and user name where needed. Examples:
M-x bbdb-create-ftp-site RET Ftp Site: news.my.domain RET Ftp Directory: /opt/news/etc/ RET Ftp Username: ssh:news RET Company: RET Additional Comments: RET
In BBDB buffer, access an entry by pressing the key F.
Thanks to TRAMP users for contributing to these recipes.
- Use simplified syntax:
- Why saved multi-hop file names do not work in a new Emacs session?
When saving ad-hoc multi-hop TRAMP file names (see Declaring multiple hops in the file name) via bookmarks, recent files, filecache, bbdb, or another package, use the full ad-hoc file name including all hops, like /ssh:bird@bastion|ssh:news.my.domain:/opt/news/etc.
Alternatively, when saving abbreviated multi-hop file names /ssh:news@news.my.domain:/opt/news/etc, the user option
tramp-save-ad-hoc-proxies
must be set non-nil
value. - How to connect to a remote Emacs session using TRAMP?
Configure Emacs Client
Then on the remote host, start the Emacs Server:
(require 'server) (setq server-host (system-name) server-use-tcp t) (server-start)
If
(system-name)
of the remote host cannot be resolved on the local host, use IP address instead.Copy from the remote host the resulting file ~/.emacs.d/server/server to the local host, to the same location.
Then start Emacs Client from the command line:
$ emacsclient /ssh:user@host:/file/to/edit
user
andhost
refer to the local host.To make Emacs Client an editor for other programs, use a wrapper script emacsclient.sh:
#!/bin/sh emacsclient /ssh:$(whoami)@$(hostname --fqdn):$1
Then change the environment variable
EDITOR
to point to the wrapper script:$ export EDITOR=/path/to/emacsclient.sh
- How to determine whether a buffer is remote?
The buffer-local variable
default-directory
tells this. If the form(file-remote-p default-directory)
returns non-nil
, the buffer is remote. See the optional arguments offile-remote-p
for determining details of the remote connection. - How to save files when a remote host isn’t reachable anymore?
If the local machine Emacs is running on changes its network integration, remote hosts could become unreachable. This happens for example, if the local machine is moved between your office and your home without restarting Emacs.
In such cases, the command
tramp-rename-files
can be used to alter remote buffers’ method, host, and/or directory names. This permits saving their contents in the same location via another network path, or somewhere else entirely (including locally). see Renaming remote files. - How to prevent TRAMP from clearing the
recentf-list
?When TRAMP cleans a connection, it removes the respective remote file name(s) from
recentf-list
. This is needed, because an unresponsive remote host could triggerrecentf
to connect that host again and again.If you find the cleanup disturbing, because the file names in
recentf-list
are precious to you, you could add the following two forms in your ~/.emacs after loading thetramp
andrecentf
packages:(remove-hook 'tramp-cleanup-connection-hook #'tramp-recentf-cleanup)
(remove-hook 'tramp-cleanup-all-connections-hook #'tramp-recentf-cleanup-all)
- I get a warning ‘Tramp has been compiled with Emacs a.b, this is Emacs c.d’
- I get an error ‘tramp-file-name-handler: Invalid function:
tramp-compat-with-mutex’
TRAMP comes with compatibility code for different Emacs versions. When you see such a message (the text might differ), you don’t use the Emacs built-in version of TRAMP, and you must recompile it. In case you have installed TRAMP from GNU ELPA, see https://www.gnu.org/software/tramp/#ELPA-Installation. Otherwise, see https://www.gnu.org/software/tramp/#Recompilation.
- I get an error ‘Remote file error: Forbidden reentrant call of Tramp’
Timers, process filters and sentinels, and other event based functions can run at any time, when a remote file operation is still running. This can cause TRAMP to block. When such a situation is detected, this error is triggered. It should be fixed in the respective function (sending an error report will help), but for the time being you can suppress this error by the following code in your ~/.emacs:
(setq debug-ignored-errors (cons 'remote-file-error debug-ignored-errors))
- I get an error ‘Remote file error: Not a valid Tramp file name
function `tramp-FOO-file-name-p'’
TRAMP has changed the signature of an internal function. External packages implementing an own TRAMP backend must follow this change. Please report this problem to the author of that package.
For the running session, TRAMP disables the external package, and you can continue to work. If you don’t want to see this error while activating TRAMP, you can suppress it by the same code as above in your ~/.emacs:
(setq debug-ignored-errors (cons 'remote-file-error debug-ignored-errors))
- How to disable other packages from calling TRAMP?
There are packages that call TRAMP without the user ever entering a remote file name. Even without applying a remote file syntax, some packages enable TRAMP on their own. How can users disable such features.
- - ido.el
Disable TRAMP file name completion:
(customize-set-variable 'ido-enable-tramp-completion nil)
- - rlogin.el
Disable remote directory tracking mode:
(rlogin-directory-tracking-mode -1)
- - ido.el
- How to disable TRAMP?
- - To keep Ange FTP as default the remote files access package, set this
in .emacs:
(customize-set-variable 'tramp-default-method "ftp")
If you want to enable Ange FTP’s syntax, add the following form:
(tramp-change-syntax 'simplified)
- -
To disable both TRAMP (and Ange FTP), set
tramp-mode
tonil
in .emacs. Note, that we don’t usecustomize-set-variable
, in order to avoid loading TRAMP.(setq tramp-mode nil)
- -
To deactivate TRAMP for some look-alike remote file names, set
tramp-ignored-file-name-regexp
to a proper regexp in .emacs. Note, that we don’t usecustomize-set-variable
, in order to avoid loading TRAMP.(setq tramp-ignored-file-name-regexp "\\`/ssh:example\\.com:")
This is needed, if you mount for example a virtual file system on your local host’s root directory as /ssh:example.com:.
- - To unload TRAMP, type M-x tramp-unload-tramp RET. Unloading TRAMP resets Ange FTP plugins also.
- - To keep Ange FTP as default the remote files access package, set this
in .emacs:
- What is the difference between Ange FTP and TRAMP?
The difference is that Ange FTP uses
ftp
to transfer files between the local and the remote host, whereas TRAMP uses a combination ofssh
andscp
or other work-alike programs.
Next: How to Customize Traces, Previous: Frequently Asked Questions, Up: TRAMP 2.6.3 User Manual [Contents][Index]
8 How file names, directories and localnames are mangled and managed
Next: Integrating with external Lisp packages, Up: How file names, directories and localnames are mangled and managed [Contents][Index]
8.1 Splitting a localname into its component parts
TRAMP package redefines lisp functions
file-name-directory
and file-name-nondirectory
to
accommodate the unique file naming syntax that TRAMP requires.
The replacements dissect the file name, use the original handler for the localname, take that result, and then re-build the TRAMP file name. By relying on the original handlers for localnames, TRAMP benefits from platform specific hacks to the original handlers.
Previous: Splitting a localname into its component parts, Up: How file names, directories and localnames are mangled and managed [Contents][Index]
8.2 Integrating with external Lisp packages
In general, it is not recommended to use TRAMP functions and variables not described in this manual. They might change their signature and/or semantics without any announcement.
8.2.1 File name completion
Sometimes, it is not convenient to open a new connection to a remote
host, including entering the password and alike. For example, this is
nasty for packages providing file name completion. Such a package
could signal to TRAMP, that they don’t want it to establish a
new connection. Use the variable non-essential
temporarily and
bind it to non-nil
value.
(let ((non-essential t)) …)
8.2.2 File attributes cache
Keeping a local cache of remote file attributes in sync with the remote host is a time-consuming operation. Flushing and re-querying these attributes can tax TRAMP to a grinding halt on busy remote hosts.
To get around these types of slow-downs in TRAMP’s
responsiveness, set the process-file-side-effects
to nil
to stop TRAMP from flushing the cache. This is helpful in
situations where callers to process-file
know there are no file
attribute changes. The let-bind form to accomplish this:
(let (process-file-side-effects) …)
For asynchronous processes, TRAMP uses a process sentinel to
flush file attributes cache. When callers to start-file-process
know beforehand no file attribute changes are expected, then the
process sentinel should be set to the default state. In cases where
the caller defines its own process sentinel, TRAMP’s process
sentinel is overwritten. The caller can still flush the file
attributes cache in its process sentinel with this code:
(unless (memq (process-status proc) '(run open)) (dired-uncache remote-directory))
Since TRAMP traverses subdirectories starting with the
root directory, it is most likely sufficient to make the
default-directory
of the process buffer as the root directory.
8.2.3 Timers
Timers run asynchronously at any time when Emacs is waiting for
sending a string to a process, or waiting for process output. They
can run any remote file operation, which would conflict with the
already running remote file operation, if the same connection is
affected. TRAMP detects this situation, and raises the
remote-file-error
error. A timer function should avoid this
situation. As a minimum, it should protect itself against this error, by
wrapping the timer function body as follows:
(ignore-error 'remote-file-error …)
Next: GNU Free Documentation License, Previous: How file names, directories and localnames are mangled and managed, Up: TRAMP 2.6.3 User Manual [Contents][Index]
9 How to Customize Traces
TRAMP messages are raised with verbosity levels ranging from 0
to 10. TRAMP does not display all messages; only those with a
verbosity level less than or equal to tramp-verbose
.
The verbosity levels are
- 0 Silent (no TRAMP messages at all)
- 1 Errors
- 2 Warnings
- 3 Connection to remote hosts (default verbosity)
- 4 Activities
- 5 Internal
- 6 Sent and received strings
- 7 Connection properties
- 8 File caching
- 9 Test commands
- 10 Traces (huge)
- 11 Call traces (maintainer only)
With tramp-verbose
greater than or equal to 4, messages are
also written to a TRAMP debug buffer. Such debug buffers are
essential to bug and problem analyzes. For TRAMP bug reports,
set the tramp-verbose
level to 6 (see Reporting Bugs and Problems).
The debug buffer is in Outline Mode. In this buffer, messages can be filtered by their level. To see messages up to verbosity level 5, enter C-u 6 C-c C-q.
TRAMP handles errors internally. Hence, to get a Lisp backtrace, the following settings are required:
(setq debug-on-error t debug-on-signal t)
If tramp-verbose
is greater than or equal to 10, Lisp
backtraces are also added to the TRAMP debug buffer in case of
errors.
In very rare cases it could happen, that TRAMP blocks Emacs. Killing Emacs does not allow inspecting the debug buffer. In that case, you can instruct TRAMP to mirror the debug buffer to a file:
(customize-set-variable 'tramp-debug-to-file t)
The debug buffer is written as a file in your
temporary-file-directory
, which is usually /tmp/. Use
this option with care, because it could decrease the performance of
TRAMP actions.
If tramp-verbose
is greater than or equal to 11, TRAMP
function call traces are written to a TRAMP trace buffer.
Next: Function Index, Previous: How to Customize Traces, Up: TRAMP 2.6.3 User Manual [Contents][Index]
Appendix A GNU Free Documentation License
Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. https://fsf.org/ Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
- PREAMBLE
The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.
This License is a kind of “copyleft”, which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.
We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.
- APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The “Document”, below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as “you”. You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.
A “Modified Version” of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language.
A “Secondary Section” is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document’s overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them.
The “Invariant Sections” are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none.
The “Cover Texts” are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words.
A “Transparent” copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not “Transparent” is called “Opaque”.
Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors for output purposes only.
The “Title Page” means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, “Title Page” means the text near the most prominent appearance of the work’s title, preceding the beginning of the body of the text.
The “publisher” means any person or entity that distributes copies of the Document to the public.
A section “Entitled XYZ” means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as “Acknowledgements”, “Dedications”, “Endorsements”, or “History”.) To “Preserve the Title” of such a section when you modify the Document means that it remains a section “Entitled XYZ” according to this definition.
The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License.
- VERBATIM COPYING
You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.
You may also lend copies, under the same conditions stated above, and you may publicly display copies.
- COPYING IN QUANTITY
If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document’s license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.
If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.
If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.
It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.
- MODIFICATIONS
You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:
- Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.
- List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement.
- State on the Title page the name of the publisher of the Modified Version, as the publisher.
- Preserve all the copyright notices of the Document.
- Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.
- Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.
- Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document’s license notice.
- Include an unaltered copy of this License.
- Preserve the section Entitled “History”, Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled “History” in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.
- Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the “History” section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.
- For any section Entitled “Acknowledgements” or “Dedications”, Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.
- Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.
- Delete any section Entitled “Endorsements”. Such a section may not be included in the Modified Version.
- Do not retitle any existing section to be Entitled “Endorsements” or to conflict in title with any Invariant Section.
- Preserve any Warranty Disclaimers.
If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version’s license notice. These titles must be distinct from any other section titles.
You may add a section Entitled “Endorsements”, provided it contains nothing but endorsements of your Modified Version by various parties—for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.
You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.
The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.
- COMBINING DOCUMENTS
You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.
The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.
In the combination, you must combine any sections Entitled “History” in the various original documents, forming one section Entitled “History”; likewise combine any sections Entitled “Acknowledgements”, and any sections Entitled “Dedications”. You must delete all sections Entitled “Endorsements.”
- COLLECTIONS OF DOCUMENTS
You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.
You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.
- AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an “aggregate” if the copyright resulting from the compilation is not used to limit the legal rights of the compilation’s users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document’s Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.
- TRANSLATION
Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail.
If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.
- TERMINATION
You may not copy, modify, sublicense, or distribute the Document except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense, or distribute it is void, and will automatically terminate your rights under this License.
However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.
Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, receipt of a copy of some or all of the same material does not give you any rights to use it.
- FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See https://www.gnu.org/licenses/.
Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License “or any later version” applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation. If the Document specifies that a proxy can decide which future versions of this License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Document.
- RELICENSING
“Massive Multiauthor Collaboration Site” (or “MMC Site”) means any World Wide Web server that publishes copyrightable works and also provides prominent facilities for anybody to edit those works. A public wiki that anybody can edit is an example of such a server. A “Massive Multiauthor Collaboration” (or “MMC”) contained in the site means any set of copyrightable works thus published on the MMC site.
“CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0 license published by Creative Commons Corporation, a not-for-profit corporation with a principal place of business in San Francisco, California, as well as future copyleft versions of that license published by that same organization.
“Incorporate” means to publish or republish a Document, in whole or in part, as part of another Document.
An MMC is “eligible for relicensing” if it is licensed under this License, and if all works that were first published under this License somewhere other than this MMC, and subsequently incorporated in whole or in part into the MMC, (1) had no cover texts or invariant sections, and (2) were thus incorporated prior to November 1, 2008.
The operator of an MMC Site may republish an MMC contained in the site under CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is eligible for relicensing.
ADDENDUM: How to use this License for your documents
To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:
Copyright (C) year your name. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the “with…Texts.” line with this:
with the Invariant Sections being list their titles, with the Front-Cover Texts being list, and with the Back-Cover Texts being list.
If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.
If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.
Next: Variable Index, Previous: GNU Free Documentation License, Up: TRAMP 2.6.3 User Manual [Contents][Index]
Function Index
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Variable Index
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Previous: Variable Index, Up: TRAMP 2.6.3 User Manual [Contents][Index]
Concept Index
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