List of all running process in Linux

To show the all running process in Linux commonly ps command used, but there are different tools are available in Linux that provides you a list of all running process on the system.

In this article I will explained all contents of ps command output. Understanding each and every field of ps command, will give a more in depth idea of processes and their different parameter’s.

List Of All Running Process

Execute the below command to list all running process on your Linux system.

[root@looklinux ~]# ps aux
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.1  0.1   2064   624 ?        Ss   08:16   0:00 init [3]
root         2  0.0  0.0      0     0 ?        S<   08:16   0:00 [migration/0]
root         3  0.0  0.0      0     0 ?        SN   08:16   0:00 [ksoftirqd/0]
root         4  0.0  0.0      0     0 ?        S<   08:16   0:00 [watchdog/0]
root         5  0.0  0.0      0     0 ?        S<   08:16   0:00 [events/0]
root         6  0.0  0.0      0     0 ?        S<   08:16   0:00 [khelper]
root         7  0.0  0.0      0     0 ?        S<   08:16   0:00 [kthread]
root        10  0.0  0.0      0     0 ?        S<   08:16   0:00 [kblockd/0]
root        11  0.0  0.0      0     0 ?        S<   08:16   0:00 [kacpid]
root       175  0.0  0.0      0     0 ?        S<   08:16   0:00 [cqueue/0]
root       178  0.0  0.0      0     0 ?        S<   08:16   0:00 [khubd]
root       180  0.0  0.0      0     0 ?        S<   08:16   0:00 [kseriod]

Let’s I will explain each and every column of the ps command output.

• USER: It gives you the name of user who started the process, you can say the owner of the process.
• PID : It gives you the PID number of the process. You can see in the ps command output the INIT process has a process id 1.
• %CPU : Display the amount of CPU in percentage, the process is currently using.
• %MEM : Display the utilized memory by the process in percentage.
• VSZ and RSS : Show the amount of memory used by the process. VSZ is used to show the amount of virtual memory used by process. RSS (Resident Set Size) is the portion of RAM (Physical Memory) that a process is using.
• TTY : Display the terminal name from where the process was started.

[root@looklinux ~]# ps aux | grep ls
root     13594  0.0  0.1   3912   672 pts/1    R+   09:46   0:00 grep ls
[root@looklinux ~]# tty
/dev/pts/1

Above tty column contains a pts/1 which is the tty name from where the command was executed. I have also confirm tty name with help of tty command.

I have also noticed in some cases, there was a question mark (?) instead of the tty name in that column. Question mark in tty field display, the process was not started from a TTY. Means the process is either a daemon or process started by the system or process related to a cron job.

I hope this article will hep to list all running process on Linux system. If you have any queries and problem please comment in comment section.

Thanks:)