nice - change priority of a process
int nice(int priority_change);
nice() adds the value of priority_change to the nice value of the
calling process. A process's nice value 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.
Upon successful completion, nice() returns the new nice value minus
20. Otherwise, a value of -1 is returned and errno is set to indicate
Note that nice() assumes a user process priority value of 20. If a
user having appropriate privileges has changed the user process
priority value to something less than 20, certain values for
priority_change can cause nice() to return -1, which is
indistinguishable from an error return.
[EPERM] nice() fails and does not change the nice value if
priority_change is negative or greater than 40, and the
effective user ID of the calling process is not a user
having appropriate privileges.
nice(1), renice(1M), exec(2).
nice(): AES, SVID2, SVID3, XPG2, XPG3, XPG4
Hewlett-Packard Company - 1 - HP-UX Release 11i: November 2000