Apache will not start. Error log contains:-

[emerg] (28)No space left on device: Couldn’t create accept lock
[crit] (28)No space left on device: mod_rewrite: could not create rewrite_log_lock Configuration Failed
Checking your disk shows that you have plenty of space. The problem is that apache didn’t shut down properly, and it’s left myriads of semaphore-arrays left, owned by my apache-user. Run:-
ipcs -s | grep nobody
Removing these semaphores immediately should solve the problem and allow apache to start.
for i in $(ipcs -s | grep nobody | awk ‘{print $2}’); do ipcrm sem $i; done