nice

nice

 [±

n

] 

command

Change the execution priority for command , or, if none is given, change priority for the current shell. (See also nice in Section 2.) The priority range is -20 to 20, with a default of 4. The range seems backwards: -20 gives the highest priority (fastest execution); 20 gives the lowest.

+ n

Add n to the priority value (lower job priority).

- n

Subtract n from the priority value (raise job priority). Privileged users only.