setlock - runs another program with a file locked.
setlock [
-nNxX ]
fn child
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.
- -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.
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