NAME    [Toc]    [Back]

     getpriority, setpriority - get/set program scheduling priority

SYNOPSIS    [Toc]    [Back]

     #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    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

     getpriority() 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 ALSO    [Toc]    [Back]

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

HISTORY    [Toc]    [Back]

     The getpriority() function call appeared in 4.2BSD.

OpenBSD      3.6                           June      4,      1993