5.7.3 Special File Name Caveats

Here is a list of things to bear in mind when using the special file names that gawk provides:

• Recognition of these special file names is disabled if gawk is in compatibility mode (see section Command-Line Options).
• gawk always interprets these special file names. For example, using ‘/dev/fd/4’ for output actually writes on file descriptor 4, and not on a new file descriptor that is dup()’ed from file descriptor 4. Most of the time this does not matter; however, it is important to not close any of the files related to file descriptors 0, 1, and 2. Doing so results in unpredictable behavior.