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 appropriately.

       EPERM  The  calling  process attempted to increase its priority by sup-
              plying 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).)

       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.

       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.

       nice(1),  renice(1), fork(2), getpriority(2), setpriority(2), capabili-
       ties(7), sched(7)

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Linux                             2015-08-08                           NICE(2)
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