The ps command can be used to view a static snapshot of active processes. The top command can be used to view processes in real time. The ps command without any options will display only the processes being used by the current user in the current shell.
[john.doe@server1 ]# ps PID TTY TIME CMD 4012 pts/2 00:00:00 bash 4657 pts/2 00:00:00 ps
Often, the grep is used with the ps command.
[john.doe@server1 ]# ps | grep foo
This will always show that the grep command itself has a PID.
john.doe 29124 23915 0 03:02 pts/0 00:00:00 grep --color=auto foo
If you want to remove grep from the output, do this.
[john.doe@server1 ]# ps | grep foo | grep -v grep