Being Nice

In a multitasking operating system (which Linux is), the kernel is responsible for assigning CPU time for each process running on the system. The scheduling priority is the amount of CPU time the kernel assigns to the process relative to the other processes. By default, all processes started from the shell have the same scheduling priority on the Linux system.

The scheduling priority is an integer value, from -20 (the highest priority) to +19 (the lowest priority). By default, the bash shell starts all processes with a scheduling priority of 0.

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Tip

It's confusing to remember that -20, the lowest value, is the highest priority and 19, the highest value, is the lowest priority. Just remember the phrase, “Nice guys finish last.” The “nicer” or higher you are in value, the lower your chance of getting the CPU.

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Sometimes, you want to change the priority of a shell script, either lowering its priority so it doesn't take as much processing...