Using renice to change the priority of a process

In the post "Using nice" we saw how we can assign a custom nice number to a process while launching it.
If we want to change the nice number of a process that is already running, then we can use the command renice.
The syntax of renice is

renice [-n] priority [[-p] pid ...] [[-g] pgrp ...] [[-u] user ...]

To find the pid of a process we can use the command pidof.
For example if we are running the gedit editor and want to get the pidof gedit, we can use

$ pidof gedit 2546

This pid can be used with the command renice. But before renice we can find the command currnet nice value of process by using the ps command

$ ps -eo cmd,pid,ni | grep gedit gedit 2546 -1 grep gedit 2674 0

We can see that the current noice number of gedit is "-1". To change it to -5 we can use renice.

$ renice -n 5 2546 2546: old priority -1, new priority -5

If we run ps now , we will notice the change in the nice number of the process.

$ ps -eo cmd,pid,ni | grep gedit gedit 2546 -5 grep gedit 2678 0

The other options of the renice are explained in the man pages.