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GETPRIORITY(2)		       System Calls Manual		  GETPRIORITY(2)

NAME
     getpriority, setpriority -- get/set program scheduling priority

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/time.h>
     #include <sys/resource.h>

     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 indi-
     cated by which and who is obtained with the getpriority() system  call  and
     set  with	the  setpriority()  system  call.   The which argument 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.  The prio argument is a value in
     the range -20 to 20.  The default priority is  0;	lower  priorities  cause
     more favorable scheduling.

     The  getpriority() system call returns the highest priority (lowest numeri-
     cal value) enjoyed by any of the specified  processes.   The  setpriority()
     system  call  sets  the priorities of all of the specified processes to the
     specified value.  Only the super-user may lower priorities.

RETURN VALUES
     Since getpriority() can legitimately return the value -1, it  is  necessary
     to  clear	the external variable errno prior to the call, then check it af-
     terward to determine if a -1 is an error or a legitimate value.

     The setpriority() function returns the value 0 if successful; otherwise the
     value -1 is returned and the global variable errno is set to  indicate  the
     error.

ERRORS
     The getpriority() and setpriority() system calls will fail if:

     [ESRCH]		No  process  was  located using the which and who values
			specified.

     [EINVAL]		The  which  argument  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.

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

HISTORY
     The getpriority() system call appeared in 4.2BSD.

FreeBSD 15.1			  June 4, 1993			  GETPRIORITY(2)
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