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.
[[email protected] ~]# 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  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.
[[email protected] ~]# ps aux | grep ls root 13594 0.0 0.1 3912 672 pts/1 R+ 09:46 0:00 grep ls [[email protected] ~]# 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.