Re: using cdb for 'update' without race condition?

ari edelkind <[email protected]> wrote:
> set -o noclobber
>
> while ! (exec >"$REMASTER_FILE") 2>&-
> do
> 	sleep 1
> done

Ah, so you're talking about O_EXCL, not locking.  Yes, that will work,
but again, you're busy-waiting instead of letting the kernel wake you
up when it's your turn.  Also, if the script gets killed in the middle
of making an update, you'll have a stale remaster file blocking all
further updates until you intervene manually.  With a permanent,
separate file used just for locking, you have no busy-waiting and (if
you're not on NFS) no chance of stale locks.


paul