NICE(3)                FreeBSD Library Functions Manual                NICE(3)

NAME
     nice - set program scheduling priority

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     nice(int incr);

DESCRIPTION
     This interface is obsoleted by setpriority(2).

     The nice() function adds incr to the scheduling priority of the process.
     The priority is a value in the range -20 to 20.  The default priority is
     0; lower priorities cause more favorable scheduling.  Only the super-user
     may lower priorities.

     Children inherit the priority of their parent processes via fork(2).

RETURN VALUES
     Upon successful completion, nice() returns 0, and errno is unchanged.
     Otherwise, -1 is returned, the process' nice value is not changed, and
     errno is set to indicate the error.

ERRORS
     The nice() function will fail if:

     [EPERM]            The incr argument is negative and the caller does not
                        have appropriate privileges.

SEE ALSO
     nice(1), fork(2), setpriority(2), renice(8)

STANDARDS
     The nice() function conforms to IEEE Std 1003.1-2008 ("POSIX.1") except
     for the return value.  This implementation returns 0 upon successful
     completion but the standard requires returning the new nice value, which
     could be -1.

HISTORY
     A nice() syscall appeared in Version 6 AT&T UNIX.

FreeBSD 13.1-RELEASE-p6        February 28, 2015       FreeBSD 13.1-RELEASE-p6