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

       nice - change process priority

       #include <unistd.h>

       int nice(int inc);

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


       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).

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

       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).)

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

       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  suc-
       cess.  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.

       nice(1), fork(2), getpriority(2), setpriority(2), capabilities(7), renice(8)

       This  page  is part of release 3.22 of the Linux man-pages project.  A description of the project, and informa-
       tion about reporting bugs, can be found at

Linux                             2007-07-26                           NICE(2)