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 super-
       user 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  appropri-
       ately.

ERRORS
       EPERM  The  calling  process  attempted  to increase its priority by supplying a negative inc but has insufficient privi-
              leges.  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 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 (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), 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)