ps - list currently running processes
$ ps [--version] [-a] [-A] [-e] [-f] [-o column-format] [-p pid-list] [--ppid pid-list] [-q pid-list] [-t tty-list] [-u user-list]Print a list of currently running processes in the current TTY. For each process, print its PID (process ID), to which TTY it belongs, and invoking commandline (CMD).
-a: Consider all processes that are associated with a TTY.
-A or -e: Consider all processes, not just those in the current TTY.
-f: Also print for each process: UID (as resolved username), PPID (parent PID), and STATE (Runnable, Sleeping, Selecting, Reading, etc.)
-o column-format: Specify a user-defined format, as a list of column format specifiers separated by commas or spaces.
A column format specifier is of the form: COLUMN_NAME[=COLUMN_TITLE]. Where COLUMN_NAME is any of the following: uid, pid, ppid, pgid, sid, state, tty, or cmd.
Specifying a COLUMN_TITLE will change the name shown in the column header. COLUMN_TITLE may be blank. If all given column titles are blank, the column header is omitted.
-p pid-list: Select processes matching any of the given PIDs. pid-list is a list of PIDs, separated by commas or spaces.
--ppid pid-list: Select processes whose PPID matches any of the given PIDs. pid-list is a list of PIDs, separated by commas or spaces.
-q pid-list: Only consider the given PIDs, if they exist. Output the processes in the order provided by pid-list. pid-list is a list of PIDs, separated by commas or spaces.
-t tty-list: Select processes associated with any of the given terminals. tty-list is a list of short TTY names (e.g: pts:0) or the full TTY device paths, separated by commas or spaces.
-u user-list: Select processes matching any of the given UIDs. user-list is a list of UIDs or login names, separated by commas or spaces.
Show all processes (full format):
$ ps -efShow the PID, state and name of all processes
$ ps -eo pid,state,cmdShow the name and state of PID 42 and rename the first column from CMD to Command:
$ ps -q 42 -o cmd=Command,stateShow name of PID 42 and omit the header entirely
$ ps -q 42 -o cmd=