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 indicated 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 numerical 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 afterward 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.

Debian                                            June 4, 1993                                    GETPRIORITY(2)