This command is a little redundant with Disk Utility, but will show you all mounted volumes (even hidden ones) and information on them. The command will output the current date, the time since last reboot, the number of users logged in, and the average system load used by those users. While not directly useful, it can provide you with a measure of how long it has been since the system has reloaded everything freshly, and can help you gauge whether a problem you're experiencing only happens after a certain amount of time after booting the system.

The uptime command shows the time that has elapsed since the system was last restarted. While getting familiar with the Terminal may seem like a daunting and unnecessary task, there are a few useful terminal commands for troubleshooting the system that can be run easily without needing to know much about the Terminal. The OS X terminal is a powerful interface with your computer that can be used to script tasks, run under-the-hood routines on your system, remotely control other systems, and perform a number of other detailed and specific actions.

Useful mac terminal commands