GETPRIORITY(2)                                                  GETPRIORITY(2)



NAME
     getpriority, setpriority - get/set program scheduling priority

SYNOPSIS
     #include <sys/resource.h>

     int getpriority (int which, idt who);

     int setpriority (int which, idt 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 PRIOPROCESS, PRIOPGRP, or
     PRIOUSER, and who is interpreted relative to which (a process identifier
     for PRIOPROCESS, process group identifier for PRIOPGRP, and a user ID
     for PRIOUSER).  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
     renice(1M), fork(2), nice(1), schedctl(2).

DIAGNOSTICS
     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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