GETPRIORITY
Section: System Calls (2)
Updated: May 22, 1986
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NAME
getpriority, setpriority - get/set program scheduling priority
SYNOPSIS
#include <sys/resource.h>
prio = getpriority(which, who)
int prio, which, who;
setpriority(which, who, prio)
int which, who, 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. Only the super-user may lower priorities.
RETURN VALUE
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.
ERRORS
Getpriority
and
setpriority
may return one of the following errors:
- [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
may fail with one of the following errors returned:
- [EPERM]
-
A process was located, but neither its effective nor real user
ID matched the effective user ID of the caller.
- [EACCES]
-
A non super-user attempted to lower a process priority.
SEE ALSO
nice(1), fork(2), renice(8)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- SEE ALSO
-
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