NAME

       nice - change the nice value of a process

SYNOPSIS

       #include <unistd.h>

       int nice(int incr);

DESCRIPTION

       The nice() function shall add the value of incr to the nice value of the calling process. A process' nice
       value 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

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

ERRORS

       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

   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

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       getpriority() ,  setpriority()  ,  the  Base  Definitions  volume  of  IEEE Std 1003.1-2001,  <limits.h>,
       <unistd.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003 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 http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                                   2003                                               NICE(P)