If you are like me who today tried to start mongod and got the error below

[initandlisten] ERROR: listen(): bind() failed errno:48 Address already in use for socket: 0.0.0.0:27017
[initandlisten] ERROR: addr already in use
[initandlisten] now exiting
Then what have to do instead of restarting your system is to find which process the mongo is running by doing

ps wuax | grep mongo

In my case it was 5687 And then just kill it with this command

kill 5687