nice(3p) — Linux manual page


NICE(3P)                POSIX Programmer's Manual               NICE(3P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

NAME         top

       nice — change the nice value of a process

SYNOPSIS         top

       #include <unistd.h>

       int nice(int incr);

DESCRIPTION         top

       The nice() function shall add the value of incr to the nice value
       of the calling process. A nice value of a process is a non-
       negative number for which a more positive value shall result in
       less favorable scheduling.

       A maximum nice value of 2*{NZERO}-1 and a minimum nice value of 0
       shall be imposed by the system. Requests for values above or
       below these limits shall result in the nice value being set to
       the corresponding limit. Only a process with appropriate
       privileges can lower the nice value.

       Calling the nice() function has no effect on the priority of
       processes or threads with policy SCHED_FIFO or SCHED_RR.  The
       effect on processes or threads with other scheduling policies is

       The nice value set with nice() shall be applied to the process.
       If the process is multi-threaded, the nice value shall affect all
       system scope threads in the process.

       As -1 is a permissible return value in a successful situation, an
       application wishing to check for error situations should set
       errno to 0, then call nice(), and if it returns -1, check to see
       whether errno is non-zero.

RETURN VALUE         top

       Upon successful completion, nice() shall return the new nice
       value -{NZERO}.  Otherwise, -1 shall be returned, the nice value
       of the process shall not be changed, and errno shall be set to
       indicate the error.

ERRORS         top

       The nice() function shall fail if:

       EPERM  The incr argument is negative and the calling process does
              not have appropriate privileges.

       The following sections are informative.

EXAMPLES         top

   Changing the Nice Value
       The following example adds the value of the incr argument, -20,
       to the nice value of the calling process.

           #include <unistd.h>
           int incr = -20;
           int ret;

           ret = nice(incr);



RATIONALE         top




SEE ALSO         top

       exec(1p), getpriority(3p)

       The Base Definitions volume of POSIX.1‐2017, limits.h(0p),

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any
       discrepancy between this version and the original IEEE and The
       Open Group Standard, the original IEEE and The Open Group
       Standard is the referee document. The original Standard can be
       obtained online at .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see .

IEEE/The Open Group               2017                          NICE(3P)

Pages that refer to this page: unistd.h(0p)nice(1p)exec(3p)getpriority(3p)