Tip of the Trade: ps Options

Admins use ps all the time to look at processes running on a system. But do you make the best use of the multitude of options this very useful tool has, or do you stick to a tiny, tested handful? Here are some ps options to check out that you may not have encountered before.

• ps r: Shows only running processes.
• ps f: Shows children descended from their parents in an ASCII art tree. I find this very useful when looking at problem processes. Use with the S option to see CPU information from children summed up with parents.

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• ps e: Shows the command environment for each process. This is useful in a situation where a program works for one user but not for another, or on one machine but not on another.
• ps -t pts/3: Shows processes associated with the specified tty. I've found this useful when trying to work out who's doing what on a remote machine, and for how long.
• ps u: Generates much more readable and human friendly output. Check the manpage for help with output column headings.

Look beyond the basics of ps, and you'll find a wide array of options for managing system processes.

Options can be combined, but note that there are three types of option: a single dash, a double dash or no dash at all. u is different from -u. When combining options, the different option types must be grouped separately (e.g., ps Sf -u jkemp.)

There are many more options that I haven't space to discuss here — go check out the manpage, and get yet more improved and exciting process info (try X or s)!