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getpriority(2)						       getpriority(2)



NAME

  getpriority, setpriority - Gets or sets process scheduling priority

SYNOPSIS

  #include <&lt;sys/resource.h>&gt;

  int getpriority(
	  int which,
	  id_t who);

  int setpriority(
	  int which,
	  id_t who,
	  int priority);

  [Tru64 UNIX]	The following declaration of the who parameter for getprior-
  ity()	and setpriority() does not conform to current standards	and is sup-
  ported only for backward compatibility:

	  int who

STANDARDS

  Interfaces documented	on this	reference page conform to industry standards
  as follows:

  getpriority(), setpriority():	XSH4.2

  Refer	to the standards(5) reference page for more information	about indus-
  try standards	and associated tags.

PARAMETERS

  which	    Specifies one of PRIO_PROCESS (process priority), PRIO_PGRP	(pro-
	    cess group priority), or PRIO_USER (user priority).

  who	    Specifies a	numeric	value interpreted relative to the which
	    parameter (a process identifier, process group identifier, and a
	    user ID, respectively).  A 0 (zero)	value for the who parameter
	    denotes the	current	process, process group,	or user.

  priority  Specifies a	value in the range -20 to 20.  The default priority
	    is 0 (zero); negative priorities cause more	favorable scheduling.

DESCRIPTION

  The getpriority() function obtains the current priority of a process,	pro-
  cess group, or user.	The getpriority() function returns the highest prior-
  ity (lowest numerical	value) pertaining to any of the	specified processes.


  The setpriority() function sets the scheduling priority of a process,	pro-
  cess group, or user.	If you specify more than one process, the setprior-
  ity()	function sets the priorities of	all of the specified processes to the
  specified value.  If the specified value is less than	-20, a value of	-20
  is used; if it is greater than 20, a value of	20 is used.

RETURN VALUES

  Upon successful completion, the getpriority()	function returns an integer
  in the range -20 to 20.  Otherwise, -1 is returned and errno is set to
  indicated the	error.

  Because 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 -1 is an error or a	legitimate value.

  Upon successful completion, the setpriority()	function returns 0 (zero).
  Otherwise, the function returns -1 and sets errno to indicate	the error.

ERRORS

  The getpriority() and	setpriority() functions	set errno to the specified
  values for the following conditions:

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

  [EINVAL]  The	which parameter	was not	recognized.

  In addition to the errors indicated above, the setpriority() function	can
  fail with errno set to one of	the following values:

  [EPERM]   The	process	does not have ownership	rights with respect to the
	    target process's real user ID.

  [EACCES]  The	process	is trying to raise its priority	and does not have the
	    appropriate	privilege.

RELATED	INFORMATION

  Functions: exec(2), nice(3)

  Standards: standards(5)