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man psName
ps - report a snapshot of the current processes.It is used to display instant information about the active processes in the system.
It accepts multiple types of arguments
- UNIX options, which may be grouped and must be preceded by a dash.
- BSD options, which may be grouped and must not be used with a dash.
- GNU long options, which are preceded by two dashes.
Examples#
ps auxIt lists out all the processes running. In my system
ps aux|wc -lroot@node1>ps aux|wc -l
244243 processes - excluding the heading.
The ps command reads the /proc filesystem which is RAM based or virtual file system.
mount -l|grep procproc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=31,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=29236)
proc on /run/docker/netns/ingress_sbox type proc (rw,nosuid,nodev,noexec,relatime)
proc on /run/docker/netns/default type proc (rw,nosuid,nodev,noexec,relatime)
proc on /run/docker/netns/1-k52v1yjsgr type proc (rw,nosuid,nodev,noexec,relatime)
proc on /run/docker/netns/e57f884c0d0f type proc (rw,nosuid,nodev,noexec,relatime)To see the process tree
ps -e --forest PID TTY TIME CMD
2 ? 00:00:00 kthreadd
4 ? 00:00:00 \_ kworker/0:0H
6 ? 00:00:00 \_ ksoftirqd/0
7 ? 00:00:01 \_ migration/0
8 ? 00:00:00 \_ rcu_bh
9 ? 00:30:31 \_ rcu_sched
10 ? 00:00:00 \_ lru-add-drain
11 ? 00:00:07 \_ watchdog/0
12 ? 00:00:06 \_ watchdog/1
13 ? 00:00:01 \_ migration/1
14 ? 00:00:01 \_ ksoftirqd/1
16 ? 00:00:00 \_ kworker/1:0H
17 ? 00:00:05 \_ watchdog/2
18 ? 00:00:04 \_ migration/2
19 ? 00:00:00 \_ ksoftirqd/2
21 ? 00:00:00 \_ kworker/2:0H
22 ? 00:00:05 \_ watchdog/3
23 ? 00:00:04 \_ migration/3
24 ? 00:00:00 \_ ksoftirqd/3
26 ? 00:00:00 \_ kworker/3:0H
27 ? 00:00:05 \_ watchdog/4
28 ? 00:00:03 \_ migration/4
