ps

Process status, information about processes running in memory.

SYNTAX
      Display Process info
         ps [-aCcefhjlMmrSTuvwx] [-O fmt] [-o fmt] [-p pid] [-t tty] [-U username]

      List all the keyword options
         ps [-L]

OPTIONS
     -a	     Display information about other users' processes as well as your own.

     -c	     Change the `command' column output to just contain the executable name
	     rather than the full command line.

     -C	     Change the way the cpu percentage is calculated by using a
	     `raw' cpu calculation that ignores `resident' time (this normally has no effect).	     

     -e	     Display the environment as well.

     -f	     Show commandline and environment information about swapped out processes.
	     This option is honored only if the uid of the user is  0.

     -h	     Repeat the information header as often as necessary to guarantee
	     one header per page of information.

     -j	     Print information associated with the following keywords: user,
	     pid, ppid, pgid, sess, jobc, state, tt, time and command.

     -L	     List the set of available keywords.

     -l	     Display information associated with the following keywords: uid,
	     pid, ppid, cpu, pri, nice, vsz, rss, wchan, state, tt, time and
	     command.

     -M	     Print the threads corresponding to each task.

     -m	     Sort by memory usage, instead of by process ID.

     -O	     Add the information associated with the space or comma separated
	     list of keywords specified, after the process ID, in the default
	     information display.  Keywords may be appended with an equals
	     (`=') sign and a string.	 This causes the printed header to use
	     the specified string instead of the standard header.

     -o	     Display information associated with the space or comma separated
	     list of keywords specified.  Keywords may be appended with an
	     equals (`=') sign and a string.	This causes the printed header
	     to use the specified string instead of the standard header.

     -p	     Display information associated with the specified process ID.

     -r	     Sort by current cpu usage, instead of by process ID.

     -S	     Change the way the process time is calculated by summing all
	     exited children to their parent process.

     -T	     Display information about processes attached to the device asso-
	     ciated with the standard input.

     -t	     Display information about processes attached to the specified
	     terminal device.

     -U	     Display the processes belonging to the specified username.

     -u	     Display information associated with the following keywords: user,
	     pid, %cpu, %mem, vsz, rss, tt, state, start, time and command.
	     The -u option implies the -r option.

     -v	     Display information associated with the following keywords: pid,
	     state, time, sl, re, pagein, vsz, rss, lim, tsiz, %cpu, %mem and
	     command.  The -v option implies the -m option.

     -w	     Use 132 columns to display information, instead of the default
	     which is your window size.	 If the -w option is specified more
	     than once, ps will use as many columns as necessary without
	     regard for your window size.

     -x	     Display information about processes without controlling termi-
	     nals.

Since ps cannot run faster than the system and is run as any other scheduled process, the information it displays can never be exact.

Related commands:

kill - Stop a process from running
lsof - List open files

Equivalent BASH command:

ps - Process status