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

       POSIX.1-2001,  POSIX.1-2008,  SVr4,  4.3BSD.  However, the Linux and (g)libc (earlier than
       glibc 2.2.4) return value is nonstandard, see below.  SVr4 documents an additional  EINVAL
       error code.

NOTES

       SUSv2  and  POSIX.1  specify  that  nice() should return the new nice value.  However, the
       Linux system call 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
       getpriority(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), renice(1), fork(2), getpriority(2), setpriority(2), capabilities(7), sched(7)

COLOPHON

       This  page  is  part of release 4.04 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at http://www.kernel.org/doc/man-pages/.