[Osiris]

Source Get to know Linux: ps command

Over the years there have been certain commands that have really helped me out of a bind. One of those commands is the ps command. The ps stands for process status and it tells you, as you would expect, the status of a process. This is a fast way to know if an application or command is running on a Linux system. Oh sure you could fire up a swell GUI for the same purpose, but that GUI does you no good if you are working on a headless server installation or working on a remote machine. In those instances the ps command is your best bet for helping to manage processes.
You will be glad to know that the ps command will most certainly be already installed on your Linux machine, so there is no need to worry about installation.

[office politics]

i've seen ps -ef used on live servers.

Learn Unix: The "ps" command

ps -ef

The -e and -f arguments are normally combined like this to show full information about every process running on the system. This is probably the most often-used form of the ps command.