xenial (2) nice.2.gz

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 setrlimit(2).)

CONFORMING TO

       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

       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.

SEE ALSO

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

COLOPHON

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