25 ps command examples in Linux [Cheat Sheet]

Introduction to ps command

In Linux, a process is any executing (running) instance of a program. Whenever you run a program, it creates a new process. Linux is a multi-tasking and multi-user operating system that allows running several programs simultaneously. So, there are multiple Linux processes running at the same time. There are different tools to view and track processes in the Linux system. This article will introduce the ps command in Linux which displays a list of currently running processes and their PIDs. ps is the short form for Process Status.

 

ps command syntax

The syntax for ps command is:

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$ ps [option]

Some options available in ps command are as follows:

  • -A: List all processes on the system
  • -e: List all processes on the system
  • x: List processes owned by the current user
  • -f: List processes with full format
  • u: Display user-oriented format

 

Different examples to use ps command

1. ps command to list all processes in the current shell

When ps command is used without any options or arguments, it displays a list of running processes in the current shell.

$ ps

Sample Output:

ps command in linux to list running processes

It displays the following information in the output.

  • PID: It shows the unique process ID.
  • TTY: It shows the terminal type into which the user is logged in.
  • TIME: It displays the total time that the process has been running.
  • CMD: It displays the name of the command that launches the process. As we can notice in the output, the second process is started by the ps command itself.

 

2. ps command to list all processes

You can use -A or -e option to list all running processes in the Linux system.

$ ps -A

OR

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$ ps -e

Sample Output:

ps command to list all processes

 

3. ps command to list all processes with a terminal

The a option causes ps to list all processes associated with a terminal (TTY).

$ ps a

Sample Output:

ps command to list all processes with a terminal

The T option allows you to select all processes associated with this terminal only.

golinux@ubuntu-PC:~$ ps T
    PID TTY      STAT   TIME COMMAND
   1925 pts/1    Ss     0:00 bash
   2200 pts/1    R+     0:00 ps T

 

4. ps command to list processes not associated with a terminal

The -a option shows all processes except both session leaders processes not associated with a terminal.

$ ps -a

Sample Output:

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ps command to list all processes not associated with a terminal

 

5. ps command to list all processes owned by the current user

The x option causes ps to list all processes owned by the current user.

$ ps x

Sample Output:

Here, ps shows all processes owned by the user golinux.

ps command to list all processes owned by the current user

 

6. List all processes in BSD format

You can combine a option with x option to list all running processes in BSD format.

$ ps ax

Sample Output:

ps command to list all processes in bsd format

 

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7. List processes with full-format

The -f option displays full format and the -F option displays extra full format.

$ ps f

OR

$ ps -F

Sample Output:

ps command to display full format

 

8. Display user-oriented format

The u option enables the user-oriented format and shows the information of the user who owns the processes.

$ ps u

Sample Output:

ps command to display user oriented format

 

9. Display virtual memory format

The v option allows you to display the processes in the virtual memory format.

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$ ps v

Sample Output:

%MEM shows the amount of memory the process is taking up.

ps command to display virtual memory format

 

10. Display processes by effective User ID or Name

The U, -u, or --user options display processes of the specified effective user name or ID.

$ ps -u user[name or id]

OR

$ ps --user user[name or id]

Sample Output:

ps command to display processes by effective user name or id

 

11. Display processes by the real user ID or Name

The -U or --User option selects the processes by the specified real user name or ID.

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$ ps -U user[name or id]

OR

$ ps --User user[name or id]

Sample Output:

ps command to list processes by real user id or name

 

12. Display processes by real group ID or name

You can list processes that belong to the specified group (real group ID or name) using -G or --Group option.

$ ps -G group[name or id]

OR

$ ps --Group group[name or id]

Sample Output:

ps command to display processes by real group id or name

 

13. Display processes by effective group ID or name

Similarly, you can use -g or --group option to list the processes owned by the specified effective group ID or name. The group ID will only work with -g when some group names are also specified. Otherwise, it lists the processes by session ID when only numeric IDs are specified.

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ps -g group_id,group_name

OR

ps --group group_id,group_name

Sample Output:

ps command to display processes by effective group id or name

 

14. List processes by process ID

The p, -p, or --pid option allows you to list specific processes using the process ID.

$ ps p process_ID

OR

$ ps - process_ID

OR

$ ps --pid process_ID

Sample Output:

golinux@ubuntu-PC:~$ ps -p 2867
PID TTY TIME CMD
2867 pts/1 00:00:00 su

You can also specify multiple process IDs.

golinux@ubuntu-PC:~$ ps -p 1320,1322,1325
PID TTY TIME CMD
1320 ? 00:00:00 gsd-rfkill
1322 ? 00:00:00 evolution-alarm
1325 ? 00:00:00 gsd-screensaver

 

15. Display specific process by using the parent process ID

The --ppid option allows you to list specific processes by parent process ID.

$ ps --ppid parent_process_ID

Sample Output:

ps command to list processes by ppid

 

16. List processes by terminal type

The t, -t, or --tty option helps to display processes having specific terminal types.

$ ps t tty_name

OR

$ ps -t tty_name

OR

$ ps --tty tty_name

Sample Output:

ps command to list processes by tty list

 

17. ps command to show environment after command

The e option causes ps to show the environment after commands in the output. e and -e options are not the same. The -e option helps to display all processes.

$ ps e

Sample Output:

golinux@ubuntu-PC:~$ ps e
    PID TTY      STAT   TIME COMMAND
    886 tty2     Ssl+   0:00 /usr/lib/gdm3/gdm-x-session --run-script env GNOME_SHELL_SESSION_MODE=ubuntu /usr/bin/gnome-session --systemd --session=ubuntu XDG_SEAT=seat0 LOGNAME=golinux USER=golinux USE
    891 tty2     Sl+    0:56 /usr/lib/xorg/Xorg vt2 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -background none -noreset -keeptty -verbose 3 USER=golinux LC_TIME=en_GB.UTF-8 LANGUAGE=en_GB:en XDG_S
    972 tty2     Sl+    0:00 /usr/libexec/gnome-session-binary --systemd --systemd --session=ubuntu LANGUAGE=en_GB:en USER=golinux LC_TIME=en_GB.UTF-8 XDG_SEAT=seat0 XDG_SESSION_TYPE=x11 SSH_AGENT_PID=10
   1840 pts/0    Ss+    0:00 bash GJS_DEBUG_TOPICS=JS ERROR;JS LOG SSH_AUTH_SOCK=/run/user/1000/keyring/ssh SESSION_MANAGER=local/ubuntu-PC:@/tmp/.ICE-unix/1143,unix/ubuntu-PC:/tmp/.ICE-unix/1143 PAPERSI
   1925 pts/1    Ss     0:00 bash GJS_DEBUG_TOPICS=JS ERROR;JS LOG SSH_AUTH_SOCK=/run/user/1000/keyring/ssh SESSION_MANAGER=local/ubuntu-PC:@/tmp/.ICE-unix/1143,unix/ubuntu-PC:/tmp/.ICE-unix/1143 PAPERSI
   3042 pts/1    S      0:00 -bash SHELL=/bin/bash PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin HOME=/home/golinux USER=golinux LOGNAME=golinux
   3136 pts/1    R+     0:00 ps e SHELL=/bin/bash LC_ADDRESS=bho_NP LC_NAME=bho_NP LC_MONETARY=bho_NP PWD=/home/golinux LOGNAME=golinux HOME=/home/golinux LC_PAPER=bho_NP LANG=en_US.UTF-8 LS_COLORS=rs=0:

 

18. Hide the header of ps command output

The h option hides the header in the output.

$ ps h

Sample Output:

ps command to hide the headers

 

19. Repeat the header lines of ps command output

The --header option is used to repeat the header lines, one per output page.

$ ps --header

Sample Output:

You will only see the effect when the output is larger than one page.

golinux@ubuntu-PC:~$ ps --headers -A
    PID TTY          TIME CMD
      1 ?        00:00:01 systemd
      2 ?        00:00:00 kthreadd
      3 ?        00:00:00 rcu_gp
      4 ?        00:00:00 rcu_par_gp
      6 ?        00:00:00 kworker/0:0H-events_highpri
      9 ?        00:00:00 mm_percpu_wq
     10 ?        00:00:00 rcu_tasks_rude_
     11 ?        00:00:00 rcu_tasks_trace
     12 ?        00:00:00 ksoftirqd/0
     13 ?        00:00:00 rcu_sched
     14 ?        00:00:00 migration/0
     15 ?        00:00:00 idle_inject/0
     16 ?        00:00:00 cpuhp/0
     17 ?        00:00:00 kdevtmpfs

 

20. ps command to display a process tree

The f or  --forest option displays an ASCII art process tree.

$ ps --forest

Sample Output:

golinux@ubuntu-PC:~$ ps --forest -A
    PID TTY          TIME CMD
      2 ?        00:00:00 kthreadd
      3 ?        00:00:00  \_ rcu_gp
      4 ?        00:00:00  \_ rcu_par_gp
    960 ?        00:00:00 \_ goa-identity-se
   1118 ?        00:00:00 \_ at-spi-bus-laun
   1124 ?        00:00:00 | \_ dbus-daemon
   1137 ?        00:00:00 \_ gnome-session-c
   1143 ?        00:00:00 \_ gnome-session-b
   1322 ?        00:00:00 | \_ evolution-alarm
   1377 ?        00:00:00 | \_ gsd-disk-utilit
   1514 ?        00:00:01 | \_ update-notifier
   1158 ?        00:03:26 \_ gnome-shell
   1181 ?        00:00:00 | \_ ibus-daemon
   1185 ?        00:00:00 | \_ ibus-dconf
   1186 ?        00:00:01 | \_ ibus-extension-
   1458 ?        00:00:00 | \_ ibus-engine-sim

You can print the process hierarchy using -H option.

   golinux@ubuntu-PC:~$ ps -H -A
    PID TTY          TIME CMD
      2 ?        00:00:00 kthreadd
      3 ?        00:00:00   rcu_gp
   1832 ?        00:00:37     gnome-terminal-
   1840 pts/0    00:00:00       bash
   1925 pts/1    00:00:00       bash
   2867 pts/1    00:00:00         su
   2868 pts/1    00:00:00           bash
   3041 pts/1    00:00:00             su
   3042 pts/1    00:00:00               bash
   4010 pts/1    00:00:00                 ps

 

21. ps command to show threads as if they were processes

The H option allows you to show threads as if they were processes.

$ ps H

Sample Output:

ps command to show threads as if they were processes

 

22. Show threads with LWP and NLWP columns

The -L option show threads, possibly with LWP (lightweight process) and NLWP (number of the lightweight processes) columns.

$ ps -L

Sample Output:

ps command to show threads with lwp and nlwp

 

23. Show format specifiers with ps command

The L option shows all format specifiers.

$ ps L

Sample Output:

ps command to show format specifiers

 

24. Display signal format with ps command

The s option is used to display signal format.

$ ps s

Sample Output:

golinux@ubuntu-PC:~$ ps s
  UID     PID          PENDING          BLOCKED          IGNORED           CAUGHT STAT TTY        TIME COMMAND
 1000     886 0000000000000000 0000000000000000 0000000000001000 0000000180014000 Ssl+ tty2       0:00 /usr/lib/gdm3/gdm-x-session --run-script env GNOME_SHELL_SESSION_MODE=ubuntu /usr/bin/gnome-session 
 1000     891 0000000000000000 0000000000000000 0000000000001000 00000001c18066ef Rl+  tty2       1:40 /usr/lib/xorg/Xorg vt2 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -background none -noreset -k
 1000     972 0000000000000000 0000000000000000 0000000000001000 0000000180004002 Sl+  tty2       0:00 /usr/libexec/gnome-session-binary --systemd --systemd --session=ubuntu
 1000    1840 0000000000000000 0000000000000000 0000000000380004 000000004b817efb Ss+  pts/0      0:00 bash
 1000    1925 0000000000000000 0000000000010000 0000000000380004 000000004b817efb Ss   pts/1      0:00 bash
 1000    3042 0000000000000000 0000000000010000 0000000000380004 000000004b817efb S    pts/1      0:00 -bash
 1000    4305 0000000000000000 0000000000000000 0000000000000000 00000001f3d1fef9 R+   pts/1      0:00 ps s

 

25. ps command to display security info

The -M option adds a column of security data and is used to get the security information of the processes.

$ ps -M

Sample output:

ps command to get security info

Conclusion

This tutorial demonstrates the different examples of ps command to display information about active processes in the Linux system. It is a very useful command to monitor running processes in the system. If you still have any confusion, please feel free to ask us in the comment section.

 

What’s Next

5 practical examples to list running processes in Linux
20 top command examples in Linux [Cheat Sheet]

 

Further Reading

man page for ps command

 

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