The Linux Cookbook provides lot of Tips and Techniques for Everyday
Use. This book is available in On-Line and Printed form.
URL: http://dsl.org/cookbook/

One Day One Command
===================

nice — Run a command with modified priority.

Summary:

GNU/Linux is a multi-user and multi-tasking OS. So many processes will
be running with some scheduling policy like Round Rabin, FIFO etc..
High priority process will get more CPU Time.

nice command is used to run the given command with its scheduling
priority adjusted. Priority range goes from -20 (highest priority)
to 19 (lowest priority).

Examples:

$ nice — Prints the current priority value.

$ nice ls — Increment the priority value of the ls command

            by 10 (Default value) and run.

$ nice -n 5 ls — Increment the priority value of the ls command

                 by 5 and run.

# nice -n -2 ls — Decrement the priority value of the ls command by

                  -2 and run.

NOTE: Incrementing the priority value will reduce the priority level

     and vice versa. Priority range is -20 (high) to 19 (low).

Read: man nice