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From: les@chinet.chi.il.us (Leslie Mikesell)
Newsgroups: comp.unix.shell
Subject: Re: SCCS and RCS over NFS (was: Creating a lock file in sh?)
Message-ID: <1991Apr22.175620.8054@chinet.chi.il.us>
Date: 22 Apr 91 17:56:20 GMT
References: <1991Apr19.201517.3679@odin.corp.sgi.com> <1991Apr20.020506.8656@twinsun.com> <28124072.1774@tct.com>
Organization: Chinet - Chicago Public Access UNIX
Lines: 20

In article <28124072.1774@tct.com> chip@tct.com (Chip Salzenberg) writes:
>>For example (Bourne shell):
>>
>>	if (umask 777;  echo >lock)
>>	then
>>		Perform whatever operation required locking.
>>		rm -f lock
>>	else
>>		Report that you could not obtain the lock.
>>	fi
>
>Unfortunately, this method is still prone to spurious failure when an
>imperfect network loses the ACK from the initial creation attempt.

Spurious failure is not nearly as bad a problem as spurious success
when creating a lockfile.  However, won't this always break when
run by root?

Les Mikesell
  les@chinet.chi.il.us