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

NAME         top

       nice - change process priority

SYNOPSIS         top

       #include <unistd.h>

       int nice(int inc);

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

       nice(): _XOPEN_SOURCE
           || /* Since glibc 2.19: */ _DEFAULT_SOURCE
           || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION         top

       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         top

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

ERRORS         top

       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

CONFORMING TO         top

       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         top

       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

       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         top

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

COLOPHON         top

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Linux                            2016-03-15                          NICE(2)