nice - change process priority
int nice(int inc));
nice adds inc to the priority for the calling pid. Only the
superuser may specify a negative increment, or priority
Note that internally, a higher number is a higher priority.
Do not confuse this with the priority scheme as used by the
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
EPERM A non-super user attempts to do a priority increase,
a numerical decrease, by supplying a negative inc.
SVr4, SVID EXT, AT&T, X/OPEN, BSD 4.3. SVr4 documents an
additional EINVAL error code.
nice(1), setpriority(2), fork(2),