gawk: Other Inherited Files

 
 5.8.1 Accessing Other Open Files with '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:
 
 '/dev/fd/N'
      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.