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1 | '\" -*- coding: UTF-8 -*- |
2 | .\" Copyright (C) 1994 Miquel van Smoorenburg. | |
3 | .\" | |
4 | .\" This program is free software; you can redistribute it and/or modify | |
5 | .\" it under the terms of the GNU General Public License as published by | |
6 | .\" the Free Software Foundation; either version 2 of the License, or | |
7 | .\" (at your option) any later version. | |
8 | .\" | |
9 | .\" This program is distributed in the hope that it will be useful, | |
10 | .\" but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | .\" GNU General Public License for more details. | |
13 | .\" | |
14 | .\" You should have received a copy of the GNU General Public License | |
15 | .\" along with this program; if not, write to the Free Software | |
16 | .\" Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
17 | .\" | |
18 | .TH POWERD 8 "Feb 14, 1994" "" "Linux System Administrator's Manual" | |
19 | .SH NAME | |
20 | .\" powerd \(em monitor a serial line connected to an UPS. | |
21 | powerd -- monitor a serial line connected to an UPS. | |
22 | .SH SYNOPSIS | |
23 | .B /sbin/powerd | |
24 | .RB " serial-device " | |
25 | .SH DESCRIPTION | |
26 | .B Powerd | |
27 | is a daemon process that sits in the background and monitors the state | |
28 | of the DCD line of the serial device. This line is meant to be | |
29 | connected to a UPS (Uninterruptible Power Supply) so that \fBpowerd\fP knows | |
30 | about the state of the UPS. As soon as \fBpowerd\fP senses that the | |
31 | power is failing (it sees that DCD goes low) it notifies \fBinit\fP(8), | |
32 | and \fBinit\fP then executes the \fBpowerwait\fP and \fBpowerfail\fP entries. | |
33 | If \fBpowerd\fP senses that the power has been restored, it notifies \fBinit\fP | |
34 | again and \fBinit\fP will execute the \fBpowerokwait\fP entries. | |
35 | .SH ARGUMENTS | |
36 | .IP serial-device | |
37 | Some serial port that is not being used by some other device, and does not | |
38 | share an interrupt with any other serial port. | |
39 | .SH DIAGNOSTICS | |
40 | \fBPowerd\fP regularly checks the \fBDSR\fP line to see if it's high. | |
41 | \fBDSR\fP should be directly connected to \fBDTR\fP and \fBpowerd\fP | |
42 | keeps that line high, so if \fBDSR\fP is low then something is wrong | |
43 | with the connection. \fBPowerd\fP will notify you about this fact every | |
44 | two minutes. When it sees that the connection has been restored it | |
45 | will say so. | |
46 | .SH HOWTO | |
47 | It's pretty simple to connect your UPS to the Linux machine. The steps | |
48 | are easy: | |
49 | .TP 0.5i | |
50 | .B 1. | |
51 | Make sure you have an UPS with a simple relay output: it should | |
52 | close its connections (make) if the power is gone, and it should | |
53 | open its connections (break) if the power is good. | |
54 | .TP 0.5i | |
55 | .B 2. | |
56 | Buy a serial plug. Connect the DTR line to the DSR line directly. | |
57 | Connect the DTR line and the DCD line with a \fB10 kilo ohm\fP | |
58 | resistor. Now connect the relay output of the UPS to GROUND | |
59 | and the DCD line. If you don't know what pins DSR, DTR, DCD and | |
60 | GROUND are you can always ask at the store where you bought the plug. | |
61 | .TP 0.5i | |
62 | .B 3. | |
63 | You're all set. | |
64 | .SH BUGS | |
65 | Well, not a real bug but \fBpowerd\fP should be able to do a broadcast or | |
66 | something on the ethernet in case more Linux-boxes are connected to | |
67 | the same UPS and only one of them is connected to the UPS status line. | |
68 | .SH SEE ALSO | |
69 | .BR shutdown (8), | |
70 | .BR init (8), | |
71 | .BR inittab (5) | |
72 | .SH AUTHOR | |
73 | Miquel van Smoorenburg, miquels@cistron.nl |