NAME

nice — set program scheduling priority

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <unistd.h>

int
nice(int incr);

DESCRIPTION

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.