nice(2)                                                             nice(2)

NAME
     nice - change priority of a time-sharing process

SYNOPSIS
     #include <unistd.h>

     int nice(int incr);

DESCRIPTION
     nice() allows a process in the time-sharing scheduling class to change
     its priority. The priocntl() system call is a more general interface
     to scheduler functions.

     nice() adds the value of incr to the nice value of the calling pro-
     cess. A process' nice value is a non-negative number for which a more
     positive value results in lower CPU priority.

     A maximum nice value is 39 and the minimum is 0 (the default value is
     20). Calls using values above or below these limits result in the
     highest value being used. Only a process with appropriate privileges
     can lower the nice value.

ERRORS
     The following error code descriptions are function-specific. You will
     find a general description in introprm2(2) or in errno(5).

     The nice() function will fail if:

     EPERM     nice() fails and does not change the nice value if incr is
               negative or greater than 39 and the effective user ID of the
               calling process is not superuser.

     EINVAL    nice() fails if called by a process in a scheduling class
               other than time-sharing.

RESULT
     Upon successful completion, nice() returns the new value minus 20.
     Otherwise, a value of -1 is returned, the process' nice value is not
     changed, and errno is set to indicate the error.

SEE ALSO
     nice(1), exec(2), priocntl(2), unistd(4).













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