4.3BSD - /usr/man/cat2/setpriority.0

GETPRIORITY(2)                                                  GETPRIORITY(2)


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)


4th Berkeley Distribution        May 22, 1986                   GETPRIORITY(2)