gawk ¶Besides the /dev/stdin, /dev/stdout, and /dev/stderr
special file names mentioned earlier, gawk provides syntax
for accessing any other inherited open file:
The file associated with file descriptor N. Such a file must
be opened by the program initiating the awk execution (typically
the shell). Unless special pains are taken in the shell from which
gawk is invoked, only descriptors 0, 1, and 2 are available.
The file names /dev/stdin, /dev/stdout, and /dev/stderr are essentially aliases for /dev/fd/0, /dev/fd/1, and /dev/fd/2, respectively. However, those names are more self-explanatory.
Note that using close() on a file name of the
form "/dev/fd/N", for file descriptor numbers
above two, does actually close the given file descriptor.