Linux Command - ps

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ps - display current processes. ps is short for Process Status.

ps displays information about a selection of the active processes. If you want a repetitive update of the selection and the displayed information, use top(1) instead.

ps has several options

  1. Unix Option - may be grouped and must be preceded by a dash
  2. BSD option - may be grouped and must NOT be preceded by a dash
  3. GNU long options, which are preceded by two dashes.

By default, ps selects all processes with the same effective user ID (euid=EUID) as the current user and associated with the same terminal as the invoker.

Syntax

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ps [options]

Options

Option Description
-a show processes not associated with a terminal
-A Select all processes. Identical to -e.
-l long format
-f full-format listing
-u userlist select by effective user ID or name
a Lift the BSD-style “only yourself” restriction
u display user-oriented format
x Lift the BSD-style “must have a tty” restriction
l display BSD long format

Example

Display all process

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ps -e

Sample output

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PID TTY          TIME CMD
  1 ?        00:01:05 systemd
  2 ?        00:00:00 kthreadd
  4 ?        00:00:00 kworker/0:0H
  6 ?        00:00:00 mm_percpu_wq
  7 ?        00:00:00 ksoftirqd/0

Display all process with full format

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ps -ef

sample output

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UID        PID  PPID  C STIME TTY          TIME CMD
xing      4470  3241  0 Dec25 ?        00:00:00 /usr/bin/zeitgeist-daemon
xing      4477  3241  0 Dec25 ?        00:00:00 /usr/lib/zeitgeist/zeitgeist/zeitgeist-fts
xing      4558  3405  0 Dec25 tty2     00:00:06 /usr/bin/gnome-software --gapplication-service
xing      4559  3405  0 Dec25 tty2     00:00:01 update-notifier
xing      4566  4559  0 Dec25 tty2     00:00:00 [livepatch-notif] <defunct>
root      4584     1  0 Dec25 ?        00:00:02 /usr/lib/fwupd/fwupd
root      4587     2  0 23:14 ?        00:00:00 [kworker/1:1]

...

Display process owned by root

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ps -f -u root

sample output

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UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 Dec25 ?        00:01:06 /sbin/init splash
root         2     0  0 Dec25 ?        00:00:00 [kthreadd]
root         4     2  0 Dec25 ?        00:00:00 [kworker/0:0H]
root         6     2  0 Dec25 ?        00:00:00 [mm_percpu_wq]
root         7     2  0 Dec25 ?        00:00:00 [ksoftirqd/0]
root         8     2  0 Dec25 ?        00:01:11 [rcu_sched]

Display all process(BSD syntax)

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ps aux

sample output

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USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
systemd+  6459  0.0  0.0  14280  1812 ?        S    Dec25   0:00 nginx: worker p
xing      6824  0.0  0.0  79960  5544 ?        S    Dec25   0:00 /usr/lib/x86_64
xing      7724  0.0  0.0 370520  7428 ?        Sl   Dec25   0:00 /usr/lib/gvfs/g
xing      7756  0.0  0.0 381288  7292 ?        Sl   Dec25   0:00 /usr/lib/gvfs/g
root     10242  0.0  0.0  10792  4840 ?        Sl   Dec25   0:02 containerd-shim
root     10262  0.0  0.0  18508  3472 pts/0    Ss+  Dec25   0:00 /bin/bash
root     11740  0.0  0.1 108092  8244 ?        Ss   09:36   0:00 /usr/sbin/cupsd
root     11741  0.0  0.1 303672 10620 ?        Ssl  09:36   0:00 /usr/sbin/cups-
xing     13042  0.0  1.8 1780472 146144 tty2   Sl+  10:05   0:37 /usr/lib/chromi
xing     13499  0.1  1.5 1751396 124020 tty2   Sl+  10:18   0:48 /usr/lib/chromi

search for a process’s PID

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ps aux | grep node

sample output

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ubuntu      9058  1.8  4.0 583200 39792 pts/4    Sl+  04:37   0:00 node index.js
ubuntu      9092  0.0  0.0   8160   736 pts/6    S+   04:38   0:00 grep --color=auto node

ps aux | grep doesn’t show the header. To show process with header

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ps aux | grep -v grep | grep -i -e VSZ -e node

You can also use pgrep process_name command to get the process id.

Reference