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.
WARNING! There are multiple versions of the nice command. One built in to the shell, and one in /bin/nice. The syntax may be diffrent on your system. Refer your shell and /bin/nice command man page for details.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.
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{ 6 comments… read them below or add one }
Can you specify one example fo nice command to run in redhat
nice is really nice !!
There’s also the renice command (from bsdutils on Debian-like distros), which is potentially less confusing.
Plz give clear explanation of nice command along with example
A good example for using nice would be to use it when taring up a huge directory. If you think that is going to impact your IO and other applications running on the server, you can use nice as such
nice -n 3 tar -cvf test.tar test_dir/*
Does nice actually work? I’ve never seen much of a scheduling/priority/load change from nicing CPU hungry tasks. I have, however, heard good things about ionice for tweaking io-heavy apps. Maybe you should both nice and ionice a process that is going to hammer the CPU and IO.
Tweeks