Re: file locking in shell scripts

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Article #147

#147

From: Tom Christiansen
Date: Fri, 24 Jul 1992 21:01

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From the keyboard of friedman@gnu.ai.mit.edu (Noah Friedman):
:You can easily create a lock file in a C program using
:
:            open (lockfile_path, O_CREAT|O_EXCL|..., mode);
:
:This is an atomic operation, so you shouldn't have to worry about any race
:conditions (locally, anyway.. I don't know if anything is guaranteed over
:NFS, including other locking methods!)

Only atomic under UNIX, not under NFS.

You must use the fcntl() method there, and good luck with your 
friend lockd.

:   Tom or Larry: can perl do this correctly?

It's really more up to the lockdaemon than to perl.  Sigh.

--tom
-- 
    Tom Christiansen      tchrist@convex.com      convex!tchrist

    All language designers are arrogant.  Goes with the territory... :-)
	    --Larry Wall in <1991Jul13.010945.19157@netlabs.com

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References: <1992Jul23.124327.20843@cv.ruu.nl> <FRIEDMAN.92Jul24055302@nutrimat.gnu.ai.mit.edu>

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Path: arc1-ca.pugleaf.net!sparky!uunet!cs.utexas.edu!hermes.chpc.utexas.edu!news.utdallas.edu!convex!tchrist
From: Tom Christiansen <tchrist@convex.COM>
Subject: Re: file locking in shell scripts
Message-ID: <1992Jul24.210130.9634@news.eng.convex.com>
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Date: Fri, 24 Jul 1992 21:01:30 GMT
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