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GETPRIORITY
!!!GETPRIORITY
NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
NOTE
CONFORMING TO
SEE ALSO
----
!!NAME


getpriority, setpriority - get/set program scheduling priority
!!SYNOPSIS


__#include __
#include __


__int getpriority(int__ ''which''__, int__
''who''__);
int setpriority(int__ ''which''__, int__
''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.
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 afterwards 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


__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 super-user attempted to lower a process
priority.
!!NOTE


Including '''' is not required these
days, but increases portability. (Indeed,
'''' defines the ''rusage''
structure with fields of type ''struct timeval'' defined
in ''''.)
!!CONFORMING TO


SVr4, 4.4BSD (these function calls first appeared in
4.2BSD).
!!SEE ALSO


nice(1), fork(2),
renice(8)
----

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Last edited on Tuesday, June 4, 2002 12:23:46 am by "perry"

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