SCCS and RCS over NFS (was: Creating a lock file in sh?)
Paul Eggert
eggert at twinsun.com
Sat Apr 20 12:05:06 AEST 1991
rhartman at thestepchild.sgi.com (Robert Hartman) writes:
>BTW, does this imply that SCCS and RCS can also fail over NFS?
>I'm not aware of them using the NFS lock manager!
I don't know about SCCS, but RCS 5.5 uses a slightly different
technique. The lock file never exists in writable form, avoiding the
NFS protocol bug that Jonathan Kamens described. A similar method can
be used in the shell. 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
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