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using grep with ps processes

You have to be careful with pulling in the output of "ps" and randomly echoing it. The "ps" lines for daemons will include a "?" in the controlling tty column, so if you did "x=`ps -e | grep whatever`", the returning line would have a "?" (on Mac OS X, two "??"). If your script then does "echo $x", the ? mark or marks will match one or two character file names that happen to be present in your current directory. As this is directory dependent, your script might appear to work correctly initially and then break later.

As to "ps", see I_WANT_A_BROKEN_PS.

From: "Stuart J. Browne" <stuart@promed.com.au>
Newsgroups: comp.unix.sco.misc
Subject: Re: for my education: "d f u" in ps -e listing
Date: Wed, 9 Aug 2000 08:41:05 +1000
Message-ID: <8mq2if$1pv$1@perki.connect.com.au> 
X-MSMail-Priority: Normal
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"Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
news:jqa0pskfi34fptv8fei3tdiubr4nq199vk@4ax.com...
> On Tue, 8 Aug 2000 15:35:14 GMT, Jean-Pierre Radley <jpr@jpr.com> wrote:
>
> >top?  I think you mean head.
>
> Y'er right.  That 3 or 4 times I've used the POP3 "head" command instead
> of top.  Now we know why I'm not a programmist.
>
> >And are you always assured that the grep process will be on the second
> >line?
>
> Because I couldn't figure out a better way to get rid of the extra line
> of output and because I've always gotten away with doing it that way.  It
> would also blow up if he had more than one named daemon running, or where
> named appears as a sub-string of some other command.  Now we know why the
> code I scribble isn't reliable.
>
> --
> Jeff Liebermann   jeffl@comix.santa-cruz.ca.us

Umm... export X=`ps -ef | grep named | grep -v grep`

one line... not the 'grep' line..  but as Tony says in the post over
there...

> You don't, you wouldn't and you haven't.  The only way you'd
> get two lines would be if you add a -f to the ps flags.

-e is friendly in that reguard.

But for the sake of this thread, '/etc/ndc status' is probably best.
Looking at the code of 'ndc', this looks for the PID listed in
/etc/named.pid, using 'ps -p <PID>', tailing the output, then grepping for
the PID.  It then counts the words in the output, and if it's 0, reports
that "named (pid <PID>?) not running". kinda messy, but suprisingly it
works.

anyway..

Bkxie
---
Yes, I am a Pixie!

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