But it's unnecessary when you can do the same thing in 2 characters.
I like flock(1) and have known how to use it for 15 years. But there's sharp edges.
- It's not standardized. In particular, this means the OpenBSD base system doesn't even include it. It's not like the underlying flock(2) is very well behaved or consistent.
- You need to ask for nonblocking behavior.
- If your command or script can ever result in a daemon launching, it may be holding the lock even though the part of your action that is supposed to be protected by the lock (the script/immediate subprocess) has ceased. so e.g. 'flock -n /tmp/relaunch-apache /etc/init.d/apache2 restart' could be a really bad idea. -u can fix this... in some cases.
