NICE(2) 						     Linux Programmer's Manual							   NICE(2)

NAME

       nice - change process priority

SYNOPSIS

       #include <unistd.h>

       int nice(int inc);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       nice(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE

DESCRIPTION

       nice()  adds  inc to the nice value for the calling process.  (A higher nice value means a low priority.)  Only the superuser may specify a
       negative increment, or priority increase.  The range for nice values is described in getpriority(2).

RETURN VALUE

       On success, the new nice value is returned (but see NOTES below).  On error, -1 is returned, and errno is set appropriately.

ERRORS

       EPERM  The calling process attempted to increase its priority by supplying a negative inc but has insufficient privileges.  Under Linux the
	      CAP_SYS_NICE capability is required.  (But see the discussion of the RLIMIT_NICE resource limit in setrlimit(2).)

CONFORMING TO

       SVr4,  4.3BSD, POSIX.1-2001.  However, the Linux and (g)libc (earlier than glibc 2.2.4) return value is nonstandard, see below.	SVr4 docu-
       ments an additional EINVAL error code.

NOTES

       SUSv2 and POSIX.1-2001 specify that nice() should return the new nice value.  However, the Linux syscall and the  nice()  library  function
       provided  in  older  versions  of  (g)libc (earlier than glibc 2.2.4) return 0 on success.  The new nice value can be found using getprior-
       ity(2).

       Since glibc 2.2.4, nice() is implemented as a library function that calls getpriority(2) to obtain the new nice value to be returned to the
       caller.	 With  this  implementation, a successful call can legitimately return -1.  To reliably detect an error, set errno to 0 before the
       call, and check its value when nice() returns -1.

SEE ALSO

       nice(1), fork(2), getpriority(2), setpriority(2), capabilities(7), renice(1)

COLOPHON

       This page is part of release 3.25 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2007-07-26								   NICE(2)