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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!news.cs.su.oz.au!metro!metro!munnari.OZ.AU!news.ecn.uoknor.edu!feed1.news.erols.com!cpk-news-hub1.bbnplanet.com!su-news-hub1.bbnplanet.com!news.bbnplanet.com!pacbell.com!amdahl.com!amd!canntp.amd.com!txnntp.amd.com!news2.amd.com!uuneo.neosoft.com!not-for-mail From: conrads@neosoft.com (Conrad Sabatier) Newsgroups: comp.unix.bsd.freebsd.misc Subject: A shell oddity (bug?) Date: Tue, 11 Mar 1997 00:23:47 -0600 Organization: NeoSoft, Inc. Lines: 28 Message-ID: <jpt2g5.q2c.ln@dolphin.neosoft.com> Reply-To: conrads@neosoft.com NNTP-Posting-Host: 206.27.167.0 X-Newsposter: Pnews 4.0-test53 (3 Feb 97) Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:37009 While fooling around tonight, trying to find a way to "lock" a program so multiple instances of it wouldn't be spawned by cron (I later discovered "lockfile"), I noticed something kind of strange. In both csh and sh (didn't try any others), the following pipeline produces some unexpected results: ps -xU news | grep fetch Assuming there's a running /usr/local/sbin/fetch (part of the leafnode package), then all one *should* see as a result would be: <PID> .... /usr/local/sbin/fetch However, sometimes the "grep fetch" itself also appears in the output! This makes no sense to me. Grep should be receiving the piped output of ps taken from *before* grep was running. Why does this happen? Conrad, still intending to whip that leafnode port into shape (I've been busy!) -- Conrad Sabatier http://www.neosoft.com/~conrads