Run a program at an altered priority (POSIX)
nice [-nprioritylevels] command [arguments]...
nice [-prioritylevels] command [arguments]...
The nice utility invokes the specified command with a modified priority, usually making the command behave “more nicely” towards competing processes.
If no prioritylevels option is specified, the program is invoked at a priority that's one level lower than the parent's current priority (i.e. it is invoked with a “nice increment” of 1).
If a prioritylevels option is specified, it's subtracted from the parent's current priority and the program is invoked at the resultant priority. If the resulting priority isn't a valid priority, nice writes a diagnostic message to the standard error and exits with a status of 1.
|If you enter:||nice:|
|A positive value (e.g. -n2 or -n+2)||Lowers the priority of the program, making it “nice”|
|A negative value (e.g. -n-2)||Raises the priority of the program, making it “mean”|
You can adjust the priority as follows:
|If you're:||You can change to any priority:|
|A non-root user||From 1 to 63|
|root||From 1 to 255|
You can change the range of privileged priorities with the -P option for procnto.
Run make at one priority lower than the parent's priority (be nice):
nice make application
Run make at two priorities lower than the parent's priority (be nicer):
nice -n2 make application
Run make at two priorities higher than the parent's priority (be mean):
nice -n-2 make application
If the operation is successful, the exit status of the invoked command is returned. If an error occurs, the exit status is as follows:
In contrast to other operating systems, the QNX Neutrino interpretation of the nice value substantially affects the priority of the process. Rather than representing a fraction of a priority, the granularity of the nice value in QNX Neutrino is of a “whole” priority level. For example, where the following has a marginal effect on the execution of myprog on some operating systems:
nice -n5 myprog
on QNX Neutrino it lowers the priority of myprog by five full priority levels, and could have a significant effect on myprog's execution time.
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