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From: stevesu@copper.UUCP (Steve Summit)
Newsgroups: net.unix,net.unix-wizards,net.wanted
Subject: Re: Need unix command file HELP!
Message-ID: <187@copper.UUCP>
Date: Mon, 17-Feb-86 21:59:22 EST
Article-I.D.: copper.187
Posted: Mon Feb 17 21:59:22 1986
Date-Received: Wed, 19-Feb-86 20:15:31 EST
References: <245@aero.ARPA>
Organization: Tektronix, Inc., Beaverton, OR
Lines: 42
Keywords: string search
Xref: linus net.unix:6577 net.unix-wizards:14004 net.wanted:7522
Summary: worry about output redirection use /dev/null to get filenames from grep

In article <245@aero.ARPA>, sutton@aero.ARPA (Stew Sutton) writes:
> We are looking for a utility that can, when given a arbitrary string,
> can locate all occurences of that string anywhere on the system. Our
> local Un*x gurus can't figure this out, so we are appealing to those out
> in Netland to help us out.

Stew's question has basically been answered, but I've got two
cents to add:

	1. Since such a command is probably going to generate
	   voluminous output, it is tempting to redirect it to a
	   file for later perusal.  If you do so, be extremely
	   careful: if your program is searching the entire
	   filesystem, it is likely to find your output file,
	   each of whose lines contains the string you're looking
	   for, and which will therefore get re-appended to the
	   file, ad infinitum...

	   I make this mistake every few years, filling up a disk
	   every time.  If you don't need to search the entire
	   filesystem, just make sure you put the output file
	   somewhere where it won't get found, like /tmp.  The
	   general solution would be an exclusion option on the
	   find command, which would be generally useful.
	   (Another trick would be to make the output file
	   unreadable.)

	2. Joe Yao pointed out the problem of the grep family not
	   printing the filename if given a single argument.  My
	   solution, which is a bit wasteful, but probably more
	   efficient than Joe's shell script, goes like this:

		find / -exec grep 'little dog' {} /dev/null \;

	   grep notices two arguments, so cheerfully prints the
	   filename if it finds the string, although it's
	   virtually guaranteed never to occur in the second one
	   (unless /dev/null accidentally got replaced with a
	   real file, but that's another story).

                                         Steve Summit
                                         tektronix!copper!stevesu