Path: utzoo!utgpu!water!watmath!clyde!rutgers!cmcl2!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.unix.wizards
Subject: Re: command line options
Message-ID: <7657@brl-smoke.ARPA>
Date: 11 Apr 88 05:51:35 GMT
References: <12907@brl-adm.ARPA>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 21

In article <12907@brl-adm.ARPA> rbj@icst-cmr.arpa (Root Boy Jim) writes:
>   From: Arthur David Olson <ado@elsie.uucp>
>       Pike's Position is that
>		   Programs that accept multiple filenames
>		   should do nothing if given no arguments.
>       This ensures that if you use a command such as
>			   cat `find * -type f -print`
>       to concatenate all the files in a directory and its subdirectories,
>       you won't get surprised when there are NO files in the directory and
>       cat starts reading from its standard input.
>Add /dev/null to the end.

The /dev/null trick is worth knowing, especially when using xargs to
grep a large number of files.

There is something to be said for a "regular" "cat" and something
to be said for the usual "cat".  The "regular" one is less surprising
and easier to use in building tools, but the usual one finds frequent
use at the head of a pipeline in shell scripts:
	cat $* | ...
I think this trick is even in Kernighan & Pike.