NICE(2) Linux Programmer's Manual NICE(2)
NAME
nice(1,2) - change process priority
SYNOPSIS
#include <unistd.h>
int nice(1,2)(int inc);
DESCRIPTION
nice(1,2) adds inc to the nice(1,2) value for the calling pid. (A large nice(1,2)
value means a low priority.) Only the superuser may specify a negative
increment, or priority increase.
RETURN VALUE
On success, zero is returned. On error(8,n), -1 is returned, and errno is
set(7,n,1 builtins) appropriately.
ERRORS
EPERM The calling process attempted to increase its priority by sup-
plying a negative inc but has insufficient privileges. Under
Linux the CAP_SYS_NICE capability is required.
CONFORMING TO
SVr4, SVID EXT, AT&T, X/OPEN, BSD 4.3. However, the Linux and glibc
(earlier than glibc 2.2.4) return value is nonstandard, see below.
SVr4 documents an additional EINVAL error(8,n) code.
NOTES
Note that the routine is documented in(1,8) SUSv2 and POSIX 1003.1-2003 to
return the new nice(1,2) value, while the Linux syscall and (g)libc (earlier
than glibc 2.2.4) routines return 0 on success. The new nice(1,2) value can
be found using getpriority(2). Note that an implementation in(1,8) which
nice(1,2) returns the new nice(1,2) value can legitimately return -1. To reli-
ably detect an error(8,n), set(7,n,1 builtins) errno to 0 before the call, and check its
value when nice(1,2) returns -1.
SEE ALSO
nice(1,2)(1), fork(2), getpriority(2), setpriority(2), capabilities(7),
renice(8)
Linux 2.6.6 2004-05-27 NICE(2)