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  setr‐
              limit(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 documents 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 (ear‐
       lier than glibc 2.2.4) return 0 on success.  The new nice value can be found using getpri‐
       ority(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 3.74 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/.



Linux                                       2014-04-28                                    NICE(2)