getpriority(3)     UNIX System V(BSD Compatibility Package)      getpriority(3)


NAME
      getpriority, setpriority - get/set program scheduling priority

SYNOPSIS
      cc [ flag. . . ] file . . . -lucb

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

      int getpriority(which, who)
      int which, who;

      int 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 getpriority and set with
      setpriority The default priority is 0; lower priorities cause more
      favorable scheduling.

      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.

      getpriority returns the highest priority (lowest numerical value) enjoyed
      by any of the specified processes.  setpriority sets the priorities of
      all of the specified processes to the value specified by prio.  If prio
      is less than -20, a value of -20 is used; if it is greater than 20, a
      value of 20 is used.  Only the privileged 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 PRIOPROCESS, PRIOPGRP, or PRIOUSER.

      In addition to the errors indicated above, setpriority may fail with one
      of the following errors returned:

      EPERM     A process was located, but one of the following is true:




10/89                                                                    Page 1

getpriority(3)     UNIX System V(BSD Compatibility Package)      getpriority(3)


                ⊕  Neither its effective nor real user ID matched the effective
                   user ID of the caller, and neither the effective nor the
                   real user ID of the process executing the setpriority was
                   the privileged user.

                ⊕  The call to getpriority would have changed a process'
                   priority to a value lower than its current value, and the
                   effective user ID of the process executing the call was not
                   that of the privileged user.

SEE ALSO
      renice(1M)

      nice(1) in the User's Reference Manual
      fork(2) in the Programmer's Reference Manual

NOTES
      It is not possible for the process executing setpriority to lower any
      other process down to its current priority, without requiring privileged
      user privileges.


































Page 2                                                                    10/89