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Annotation of 43BSDReno/lib/libc/sys/getpriority.2, revision 1.1.1.1

1.1       root        1: .\" Copyright (c) 1980 The Regents of the University of California.
                      2: .\" All rights reserved.
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                     15: .\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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                     18: .\"    @(#)getpriority.2       6.8 (Berkeley) 6/23/90
                     19: .\"
                     20: .TH GETPRIORITY 2 "June 23, 1990"
                     21: .UC 4
                     22: .SH NAME
                     23: getpriority, setpriority \- get/set program scheduling priority
                     24: .SH SYNOPSIS
                     25: .nf
                     26: .ft B
                     27: #include <sys/time.h>
                     28: #include <sys/resource.h>
                     29: .PP
                     30: .ft B
                     31: prio = getpriority(which, who)
                     32: int prio, which, who;
                     33: .PP
                     34: .ft B
                     35: setpriority(which, who, prio)
                     36: int which, who, prio;
                     37: .fi
                     38: .SH DESCRIPTION
                     39: The scheduling
                     40: priority of the process, process group, or user, as indicated by
                     41: .I which
                     42: and
                     43: .I who
                     44: is obtained with the
                     45: .I getpriority
                     46: call and set with the
                     47: .I setpriority
                     48: call.
                     49: .I Which
                     50: is one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER, and 
                     51: .I who
                     52: is interpreted relative to 
                     53: .I which
                     54: (a process identifier for PRIO_PROCESS, process group
                     55: identifier for PRIO_PGRP, and a user ID for PRIO_USER).
                     56: A zero value of
                     57: .I who
                     58: denotes the current process, process group, or user.
                     59: .I Prio
                     60: is a value in the range \-20 to 20.  The default priority is 0;
                     61: lower priorities cause more favorable scheduling.
                     62: .PP
                     63: The
                     64: .I getpriority
                     65: call returns the highest priority (lowest numerical value)
                     66: enjoyed by any of the specified processes.  The
                     67: .I setpriority
                     68: call sets the priorities of all of the specified processes
                     69: to the specified value.  Only the super-user may lower priorities.
                     70: .SH "RETURN VALUE
                     71: Since
                     72: .I getpriority
                     73: can legitimately return the value \-1, it is necessary
                     74: to clear the external variable \fIerrno\fP prior to the
                     75: call, then check it afterward to determine
                     76: if a \-1 is an error or a legitimate value.
                     77: The
                     78: .I setpriority
                     79: call returns 0 if there is no error, or
                     80: \-1 if there is.
                     81: .SH ERRORS
                     82: .I Getpriority
                     83: and
                     84: .I setpriority
                     85: may return one of the following errors:
                     86: .TP 15
                     87: [ESRCH]
                     88: No process was located using the 
                     89: .I which
                     90: and
                     91: .I who
                     92: values specified.
                     93: .TP 15
                     94: [EINVAL]
                     95: .I Which
                     96: was not one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER.
                     97: .PP
                     98: In addition to the errors indicated above,
                     99: .I setpriority
                    100: may fail with one of the following errors returned:
                    101: .TP 15
                    102: [EPERM]
                    103: A process was located, but neither its effective nor real user
                    104: ID matched the effective user ID of the caller.
                    105: .TP 15
                    106: [EACCES]
                    107: A non super-user attempted to lower a process priority.
                    108: .SH "SEE ALSO"
                    109: nice(1), fork(2), renice(8)

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