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From: guy%gorodish@Sun.COM (Guy Harris)
Newsgroups: comp.unix.wizards
Subject: Re: Using argv to show process status
Message-ID: <26253@sun.uucp>
Date: Fri, 21-Aug-87 15:29:01 EDT
Article-I.D.: sun.26253
Posted: Fri Aug 21 15:29:01 1987
Date-Received: Sun, 23-Aug-87 04:34:47 EDT
References: <1217@mhres.mh.nl> <26252@sun.uucp>
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Keywords: argv ps

> In short, this trick is NOT portable; it may be a nice hack, but don't depend
> on it working.

In addition, as Doug Gwyn points out, if the string you're writing is longer
than the original argument, you will start scribbling on top of other strings,
such as other arguments or environment variables.  You *might*, conceivably, be
able to save the arguments away before you smash them; however, it's not so
easy to save the environment variables, because some routine you don't even
know about may want to query one of them!  You might be able to save them all,
zero out your environment, and reconstruct it with "putenv" on a system that
has "putenv"; however, it sounds like too much trouble.

If you want to do this sort of thing, make VERY SURE you always overwrite the
zeroth argument with exactly as many characters as it originally had,
truncating or padding with NUL characters as needed.  If the truncation is a
problem, too bad.

Remember, this trick depends on a *quirk of the implementation*; vendors are
under no obligation whatsoever to provide implementations with this quirk.
	Guy Harris
	{ihnp4, decvax, seismo, decwrl, ...}!sun!guy
	guy@sun.com