GETPRIORITY(2)							GETPRIORITY(2)

NAME    [Toc]    [Back]

     getpriority, setpriority -	get/set	program	scheduling priority

SYNOPSIS    [Toc]    [Back]

     #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.  Only the super-user may lower priorities.

     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    [Toc]    [Back]

     renice(1M), fork(2), nice(1), schedctl(2).

DIAGNOSTICS    [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.


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