nice(2)nice(2)NAMEnice - change priority of a process
adds the value of priority_change to the nice value of the calling
process. A process's is a positive number for which a more positive
value results in lower CPU priority.
A maximum nice value of 39 and a minimum nice value of 0 are imposed by
the system. Requests for values above or below these limits result in
the nice value being set to the corresponding limit.
If the calling process contains more than one thread or lightweight
process (i.e., the process is multi-threaded) this function shall apply
to all threads or lightweight processes in the calling process.
Some or all of the actions associated with this system call are subject
to compartmental restrictions. See compartments(5) for more information
about compartmentalization on systems that support that feature. Com‐
partmental restrictions can be overridden if the process possesses the
privilege (COMMALLOWED). Processes owned by the superuser may not have
this privilege. Processes owned by any user may have this privilege,
depending on system configuration.
Some or all of the actions associated with this system call require the
(OWNER) and/or the (LIMIT) privileges. Processes owned by the supe‐
ruser will have these privileges. Processes owned by other users may
have privilege(s), depending on system configuration. See privi‐
leges(5) for more information about privileged access on systems that
support fine-grained privileges.
Upon successful completion, returns the new nice value minus 20. Oth‐
erwise, a value of −1 is returned and is set to indicate the error.
Note that assumes a user process priority value of 20. If a user hav‐
ing appropriate privileges has changed the user process priority value
to something less than 20, certain values for priority_change can cause
to return −1, which is indistinguishable from an error return.
[EPERM] fails and does not change the nice value if prior‐
ity_change is negative or greater than 40, and the
effective user ID of the calling process is not a user
having appropriate privileges.
SEE ALSOnice(1), renice(1M), exec(2), privileges(5).