GETPRIORITY(2) OpenBSD Programmer's Manual GETPRIORITY(2)NAME
getpriority, setpriority - get/set program scheduling priority
SYNOPSIS
#include <sys/time.h>
#include <sys/resource.h>
int
getpriority(int which, id_t who);
int
setpriority(int which, id_t who, int prio);
DESCRIPTION
The scheduling priority of the process, process group, or user, as
indicated by which and who is obtained with the getpriority() call and
set with the setpriority() call. which is one of PRIO_PROCESS,
PRIO_PGRP, or PRIO_USER, and who is interpreted relative to which (a
process identifier for PRIO_PROCESS, process group identifier for
PRIO_PGRP, and a user ID for PRIO_USER). A zero value of who denotes the
current process, process group, or user. prio is a value in the range
-20 to 20. The default priority is 0; lower priorities cause more
favorable scheduling.
The getpriority() call returns the highest priority (lowest numerical
value) enjoyed by any of the specified processes. The setpriority() call
sets the priorities of all of the specified processes to the specified
value. Priority values outside the range -20 to 20 are truncated to the
appropriate limit. Only the superuser may lower priorities.
RETURN VALUES
Since getpriority() can legitimately return the value -1, it is necessary
to clear the external variable errno prior to the call, then check it
afterward to determine if a -1 is an error or a legitimate value. The
setpriority() call returns 0 if there is no error, or -1 if there is.
ERRORSgetpriority() and setpriority() will fail if:
[ESRCH] No process was located using the which and who values
specified.
[EINVAL] which was not one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER.
In addition to the errors indicated above, setpriority() will fail if:
[EPERM] A process was located, but neither its effective nor real
user ID matched the effective user ID of the caller.
[EACCES] A non-superuser attempted to lower a process priority.
SEE ALSOnice(1), fork(2), renice(8)HISTORY
The getpriority() function call appeared in 4.2BSD.
OpenBSD 4.9 May 31, 2007 OpenBSD 4.9