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These options are to do with the input and outputs of the various programs.
(=STR) The number or name of the desired Header Data Unit or
HDU in the input FITS image or images. A FITS file can store multiple
HDUs or extensions, each with either an image or a table or nothing at
all (only a header). Note that counting of the extensions starts from
0(zero), not 1(one). When specifying the name, case is not important
so IMAGE, image or ImAgE are equivalent.
A # is appended to the string you specify for the
HDU42 and the result is put in square brackets and appended to the
FITS file name before calling CFITSIO to read the contents of the HDU
for all the programs in Gnuastro. CFITSIO has many capabilities to
help you find the extension you want, far beyond the simple extension
number and name. See CFITSIO manual’s “HDU Location Specification”
section for a very complete explanation with several examples.
Note that in some programs, the behavior of --hdu might be different, for example see Invoking Arithmetic, were it can be called multiple times and the value of each all will be stored.
(=STR) The name of the output file or directory. With this option the automatic output names explained in Automatic output are ignored.
By default, if the output file already exists, it will be silently replaced with the output of this run of all Gnuastro programs. By calling this option, if the output file already exists, the programs will warn you and abort.
In automatic output names, don’t remove the directory information of the input file names. As explained in Automatic output, if no output name is specified, then the output name will be made in the existing directory based on your input. If you call this option, the directory information of the input will be kept and the output will be in the same directory as the input. Note that his is only relevant if you are running the program from another directory!
With the # character, CFITSIO will only read the
desired HDU into your memory, not all the existing HDUs in the fits
file.
Next: Operating modes, Previous: Common options, Up: Common options [Contents][Index]
GNU Astronomy Utilities 0.2.28-34fb manual, October 2016.