Q. How do I run a process with modified scheduling priority under Linux? I'd like to change the priority in the kernel's scheduler while starting a command.
A. Use nice command to run a program with modified scheduling priority / nicenesses. Nicenesses range at least from -20 (resulting in the most favorable scheduling) through 19 (the least favorable). The default behavior is to increase the niceness by 10.
A niceness should not be confused with a scheduling priority, which lets applications determine the order in which threads are scheduled to run. Unlike a priority, a niceness is merely advice to the scheduler, which the scheduler is free to ignore.
nice syntax (/bin/nice command)
/bin/nice -n NUM
Add integer NUM (-20 to 19) to the niceness.
Change niceness by 3
Type the command as follows:
$ /bin/nice -n 3 command-name
Only a privileged user may run a process with lower niceness:
$ /bin/nice -n -1 command-name
Shell in build nice command syntax
If you use the csh or tcsh or bash, the syntax is as follows:
nice +n command
I recommend using /bin/nice syntax to avoid confusion and to save time.