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From: knudsen@cbnewsd.att.com (michael.j.knudsen)
Newsgroups: comp.os.os9
Subject: Re: SILENT ERROR exits SHell script?
Keywords: OSK shell bug
Message-ID: <1991Jun7.220255.13394@cbnewsd.att.com>
Date: 7 Jun 91 22:02:55 GMT
References: <1991Jun4.230458.25390@cbnewsd.att.com> <1991Jun5.184640.4481@wam.umd.edu>
Organization: AT&T Bell Laboratories
Lines: 36

In article <1991Jun5.184640.4481@wam.umd.edu>, ignatz@wam.umd.edu (Mark J. Sienkiewicz) writes:
> Microware's shell exits whenever a process returns a non-zero exit code.
> The exit code you are getting is 1 (or 000:001 in microware terms).  This
> error seems to get special treatment by not being printed, but only
> if you ar executing a script.  Is this weird or what?

Well, I can see the special treatment of Error #001 as being
forward-looking on Microware's part, in case they ever put
conditional branching in their Shell (along with a few other things
that are way overdue, like command-line args...)
 
> Here are the standard exit codes for diff:
> 	0 no differences
> 	1 the two files are different
> 	2 some error occured

OK -- sure sounds like this diff was intended for Un*x usage.
Why else would it use OS9's BREAK error code?
Still wondering whether the -X switch will keep the OSK script from
exiting whenever the files are different.

> I would also ask "Why do you have diff in a shell script?"

Easy.  I want to diff several file pairs, and concatenate the diffs
into one master file.  Whenever I make an incremental backup, using
DSAVE with the -DR options, I first do a dry run and put the DSAVE
generated script into a temp file, and edit it to do DIFFs between
the new and old versions of the files.  Thus I get a record of
changes.

Anyway, a command that you can't use in a script in case it
actually does some real work (ie, find differences) is pretty silly.
I'll try the -X in the scripyt next time.
-- 
"What America needs is A Thousand Points When Lit..."
	knudsen@ihlpl.att.com