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From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.unix.questions
Subject: Re: distinguishing pipes from files
Message-ID: <6712@brl-smoke.ARPA>
Date: Sat, 21-Nov-87 19:58:07 EST
Article-I.D.: brl-smok.6712
Posted: Sat Nov 21 19:58:07 1987
Date-Received: Mon, 23-Nov-87 05:43:19 EST
References: <454@rocksanne.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 14

In article <454@rocksanne.UUCP> fuss@rocksanne.UUCP (William Fuss) writes:
>Can a process can recognize the "source" of its input/output ???

Yes, the usual way is to perform an fstat() system call on the
file descriptor, then use some of the macros defined in <sys/stat.h>
on the st_mode field of the data structure returned by fstat()
to determine the inode type (regular file, FIFO/pipe, directory,
etc.).

Another thing that is sometimes done to test whether a file
descriptor is associated with a terminal port is to do an
ioctl() to get terminal handler parameters.  If the ioctl()
fails, presumably the inode is not a terminal.  This is
usually packaged as isatty() in the UNIX C library.