Currently, mongod.lock is created in the data directory by the mmapv1 initialization code and is not present when another storage engine (eg. WiredTiger) is selected.

We should always ensure that this file is created (and locked) regardless of the storage engine used.

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The --shutdown switch (Linux-specific) doesn't work with WiredTiger because the --shutdown code checks for a non-existent mongod.lock file:

https://github.com/mongodb/mongo/blob/b0014456ddefaccf02016c1a89c514e865a099d6/src/mongo/db/db.cpp#L722-L729

$ ./mongod --storageEngine=wiredTiger --fork --logpath=foo.log
about to fork child process, waiting until server is ready for connections.
forked process: 3680
child process started successfully, parent exiting

$ ./mongod --shutdown
There doesn't seem to be a server running with dbpath: /data/db

Version: b0014456dd