12-10-2001
A "lock" file is nothing more than an ordinary file
that is used a a sort of "semaphore". Meaning, for example,
you can create a lock file from within a shell script
(say "myprog.ksh")
that can contain the shell script's process ID by doing...
echo $$ > /tmp/myprog..LCK
...this will create the file called "myprog..LCK" in the
"/tmp" directory. This file will contain the process id of
the shell script "myprog.ksh" for that particular instance
in which it was run.
There are several good reasons to do this. For instance,
"myprog.ksh" may be executed every 60min via "cron" but
occasionally make take more than 60min to complete. Therefore
you may wish to skip execution if the previous execution
is still running.
However, I'm not exactly clear on your requirements. It may
be that a lock file is not necessary. For example, if you wanted to
execute a shell script every 60min you could simply create a
"cron" job to run at 60min intervals.
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LEARN ABOUT DEBIAN
setlock
setlock(8) System Manager's Manual setlock(8)
NAME
setlock - runs another program with a file locked.
SYNOPSIS
setlock [ -nNxX ] fn child
DESCRIPTION
fn is a single argument. child consists of one or more arguments.
setlock opens fn for writing (creating it if it does not exist), obtains an exclusive lock on it, and runs child.
Normally the lock disappears when child exits.
Here's the complete story: child is given a descriptor for a locked ofile pointing to the disk file named fn. The lock disappears when
this ofile is
o closed by all the processes that have descriptors for it or
o explicitly unlocked.
OPTIONS
-n No delay. If fn is locked by another process, setlock gives up.
-N (Default.) Delay. If fn is locked by another process, setlock waits until it can obtain a new lock.
-x If fn cannot be opened (or created) or locked, setlock exits zero.
-X (Default.) If fn cannot be opened (or created) or locked, setlock prints an error message and exits nonzero.
SEE ALSO
supervise(8), svc(8), svok(8), svstat(8), svscanboot(8), svscan(8), readproctitle(8), fghack(8), pgrphack(8), multilog(8), tai64n(8),
tai64nlocal(8), setuidgid(8), envuidgid(8), envdir(8), softlimit(8)
http://cr.yp.to/daemontools.html
setlock(8)