PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

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
       implementation-defined.

       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);

APPLICATION USAGE         top

       None.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       exec(1p), getpriority(3p)

       The Base Definitions volume of POSIX.1‐2008, limits.h(0p),
       unistd.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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 http://www.unix.org/online.html .

       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
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                            NICE(3P)