How To Find Out How Long A Process Has Been Running In Linux

Ever wanted to know how long a process has been running on your Linux box? Well, it is your luck day! This brief guide helps you to find out the uptime of an active process. You don't need any monitoring applications. In Unix-like operating systems, there is a command called ps, which is used to display the information about the active processes. Using ps command, we can easily find out how long a process is running.

Find Out How Long A Process Has Been Running In Linux

The ps command has different format specifiers (keywords) that can be used to control the output format. We are going to use the following two keywords to find the uptime of an active process.

• etime - elapsed time since the process was started, in the form of [[DD-]hh:]mm:ss.
• etimes - elapsed time since the process was started, in seconds.

First, you need to find out the PID of a process. The following command displays the PID of dhcpcd process.

$ pidof dhcpcd
8299

As you see in the above output, 8299 is the PID of dhcpcd process.

Now, we can find how long this process has been running using command:

$ ps -p 8299 -o etime
 ELAPSED
 04:05:37

You can also view the elapsed time in seconds using etimes keyword.

$ ps -p 8299 -o etimes
ELAPSED
 14749

Find Out How Long A Process Has Been Running In Linux

Not only a single process, we can also display the uptime of all processes like below.

$ ps -eo pid,comm,lstart,etime,time,args

Or,

$ ps -eo pid,comm,lstart,etimes,time,args

The first command displays the uptime of all Linux processes, in [[DD-]hh:]mm:ss format, and the latter displays the uptime in seconds. Here is the sample output of second command.

As you see in the above output, we have the uptime of all processes with six columns format.

Here,

• PID - The Process ID.
• COMMAND(second column) - The command name without options and/or arguments.
• STARTED - The absolute starting time of the process.
• ELAPSED - The elapsed time since the process was started, in the form of [[dd-]hh:]mm:ss.
• TIME - Cumulative CPU time, "[dd-]hh:mm:ss" format.
• COMMAND (last column) - Command name with all its provided options and arguments.

For more details about ps command, check the man pages.

$ man ps

Suggested read:

• How To Change The Priority Of A Process In Linux
• How To Display Process Information Using Procs On Linux

And, that's all for now. You know now how to find out how long a process is running in your Linux system. Hope this helps.