launchd
After installing mongodb using homebrew, and following the information that homebrew provided, I did the following:
launchctl load -w ~/Library/LaunchAgents/org.mongodb.mongod.plist
But got the following error:
Bug: launchctl.c:2406 (25182):13: (dbfd = open(g_job_overrides_db_path, O_RDONLY | O_EXLOCK | O_CREAT, S_IRUSR | S_IWUSR)) != -1
launch_msg(): Socket is not connected
Mongodb starts fine in a terminal.
If a plist is owned by root and writable by a user other than root, that's a security issue.
You can change the owner to root with sudo chown root <filename>, and change the permissions with sudo chmod 644 <filename> (4 for read access, 2 for write access, 1 for execute access, added up. The first number is for the owner, the second for the group, the third for everyone.)
Try moving the plist to /Library/LaunchDaemons/. Agents (other than pre-login agents) are run only after a user logs in and they are owned by the user. Also the UserName key has no effect for agents.
See the Daemons and Agents tech note.
Best Answer
It seems like the problem was tmux. When executing launchctl without tmux running this bug doesn't occur.