Use the ps command to see what processes are currently running.The ps command shows the process identification number (listed under PID) for each process you own, which is created after you type a command. This command also shows you the terminal from which it was started (TTY), the cpu time it has used so far (TIME), and the command it is performing (COMMAND).
If you add the -l option to the ps command, the system displays other process information, including the state of each running process (listed under S). The following list defines the codes used to describe processes.
O – Process is running on a processor
Note that while ps is running, the status of an individual process can change. Since the ps command gives you only a snapshot of what's going on at the moment you issue the command, the output is only accurate for a split second after you type the command.
The ps(1) command has more options than those covered here. Refer to the man Pages(1): User Commands.