ps — Report Process Status
/usr/bin/ps [-aAcdefjlLPy][-g grplist][-n namelist [[-o format]...] [-p proclist][-s sidlist][-t term][-u uidlist][-U uidlist] [-G gidlist]
Use the ps command to determine process status and get detailed information about an individual process, such as:
PID (process ID).
UID (user ID).
The ps command takes a snapshot of system activity at the time you type the command. Some data printed for defunct processes is irrelevant. If you are monitoring system activity by time, be aware that the results are already slightly out-of-date by the time you read them.
When you type the ps command without options, ps prints information about processes ...