Any command returns error:
stat: cannot stat '/var/lib/minecraft/servers/default/minecraft.sh.lock': No such file or directory /var/lib/minecraft/minecraft_base.sh: line 660: ((: 1437525346 - > 30 : syntax error: operand expected (error token is "> 30 ") Another process is currently running the server control script - aborting. The other process is: cat: /var/lib/minecraft/servers/default/minecraft.sh.lock: No such file or directory failed to lock!
Well, for some reason /var/lib/minecraft/servers/default/minecraft.sh.lock is not correctly created, I am guessing. Does /var/lib/minecraft/servers/default/ have the right ownership and permissions?
There are two callers to lock_timed_out() where the error is occuring - can you find out which one of the call paths is generating the error?