1sensord(8) Linux System Administration sensord(8)
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6 sensord - Sensor information logging daemon.
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9 sensord [ options ] [ chips ]
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13 Sensord is a daemon that can be used to periodically log sensor read‐
14 ings from hardware health-monitoring chips to syslog(3) or a round-
15 robin database (RRD) and to alert when a sensor alarm is signalled; for
16 example, if a fan fails, a temperature limit is exceeded, etc.
17 Sensord knows about certain chips, and outputs nicely formatted read‐
19 ings for them; but it can also display the information of unknown
20 chips, as long as libsensors(3) knows about them.
21
23 -i, --interval time
24 Specify the interval between scanning for sensor alarms; the
25 default is to scan every minute.
26 The time should be specified as a raw integer (seconds) or with
28 a suffix `s' for seconds, `m' for minutes or `h' for hours; for
29 example, the default interval is `60' or `1m'.
30 Specify an interval of zero to suppress scanning explicitly for
32 alarms.
33 -l, --log-interval time
35 Specify the interval between logging all sensor readings; the
36 default is to log all readings every half hour.
37 The time is specified as before; e.g., `30m'.
39 Specify an interval of zero to suppress logging of regular sen‐
41 sor readings.
42 -t, --rrd-interval time
44 Specify the interval between logging all sensor readings to a
45 round-robin database; the default is to log all readings every
46 five minutes if a round-robin database is configured.
47 The time is specified as before; e.g., `5m'.
49 -T, --rrd-no-average
51 Specify that the round-robin database should not be averaged.
52 -r, --rrd-file file
55 Specify a round-robin database into which to log all sensor
56 readings; e.g., `/var/log/sensord.rrd'. This database will be
57 created if it does not exist. By default, no round-robin data‐
58 base is used.
59 See the section ROUND ROBIN DATABASES below for more details.
61 -c, --config-file file
63 Specify a libsensors(3) configuration file. If no file is speci‐
64 fied, the name `sensors.conf' is used.
65 If the sensors configuration name does not contain a directory
67 separator, the following paths are searched for the file:
68 `/etc', `/usr/lib/sensors', `/usr/local/lib/sensors',
69 `/usr/lib', `/usr/local/lib'.
70 -p, --pid-file file
72 Specify what PID file to write; the default is to write the file
73 `/var/run/sensord.pid'. You should always specify an absolute
74 path here. The file is removed when the daemon exits.
75 -f, --syslog-facility facility
77 Specify the syslog(3) facility to use when logging sensor read‐
78 ings and alarms; the default is to use local4.
79 Other possibile facilities include local0 through local7, daemon
81 or user.
82 -g, --rrd-cgi directory
84 Prints out a sample rrdcgi(1) CGI script that can be used to
85 display graphs of recent sensor information in a Web page, and
86 exits. You must specify the world-writable, Web-accessible
87 directory where the graphs should be stored; the CGI script
88 assumes that this will be accessed under the `/sensord/' direc‐
89 tory on the Webserver. See the section ROUND ROBIN DATABASES
90 below for more details.
91 -a, --load-average
93 Include the load average in the RRD database. You should also
94 specify this flag when you create the CGI script.
95 -d, --debug
97 Prints a small amount of additional debugging information.
98 -h, --help
100 Prints a help message and exits.
101 -v, --version
103 Displays the program version and exits.
104
106 To restrict the devices that are scanned by this daemon, you may
107 optionally specify a list of chip names. By default, all available
108 chips are scanned.
109 A typical chip name would be `w83782d-*' (you may want to escape the
111 `*' for your shell) which would scan any W83782D chips on any bus. See
112 sensors.conf(5) for more details. Another option is to simply not load
113 the sensor modules for chips in which you have no interest.
114
116 Upon receipt of a SIGTERM (see signal(7) for details) this daemon
117 should gracefully shut down.
118
120 All messages from this daemon are logged to syslog(3) under the program
121 name `sensord' and facility local4, or whatever is specified on the
122 command line.
123 Regular sensor readings are logged at the level info. Alarms are
125 logged at the level alert. Inconsequential status messages are logged
126 at the minimum level, debug, when debugging is enabled.
127 You can use an appropriate `/etc/syslog.conf' file to direct these mes‐
129 sages in a useful manner. See syslog.conf(5) for full details, however
130 the following is a sample configuration:
131 # Sample syslog.conf entries
133 *.info;...;local4.none;local4.warn /var/log/messages
134 local4.info -/var/log/sensors
135 local4.alert /dev/console
136 local4.alert *
137 The first line ensures that regular sensor readings do not clutter
139 `/var/log/messages'; we first say `local4.none' to eliminate informa‐
140 tional messages; then `local4.warn' to enable warnings and above. The
141 second line says to log all regular sensor readings to `/var/log/sen‐
142 sors'; the leading hyphen `-' means that this file is not flushed after
143 every message. The final two lines ensure that alarms are printed to
144 the system console as well as to all connected users (in addition to
145 `/var/log/messages' and `/var/log/sensors').
146
148 On a typical system with a good sensor chip, expect about 2KB per sen‐
149 sor reading in the log file. This works out at about 3MB per month. You
150 should be rotating your syslog files anyway, but just to be sure you'll
151 want to use something like logrotate(8) or equivalent. You might, for
152 example, want an entry in `/etc/logrotate.d/syslog' containing:
153 # Sample logrotate.d entry
155 /var/log/sensors {
156 postrotate
157 /usr/sbin/killall -HUP syslogd
158 endscript
159 }
160 Note, of course, that you want to restart syslogd(8) and not sensord(8)
162
164 Alarms generally indicate a critical condition; for example, a fan
165 failure or an unacceptable temperature or voltage. However, some sensor
166 chips do not support alarms, while others are incorrectly configured
167 and may signal alarms incorrectly.
168 Sometimes, uninteresting alarms (e.g., chassis intrusion detection)
170 will be repeated continuously. You can configure libsensors(3) to
171 ignore unwanted sensor reading such as these by placing an `ignore'
172 entry in the appropriate chip-specific section of the sensors.conf(5)
173 configuration file.
174 For example, I have the following entry:
176 # Sample /etc/sensors.conf entry
178 chip "w83782d-*"
179 ignore "alarms"
180 In this case, `alarms' was the sensor label reported in the relevant
182 sensor log message.
183 Alternatively, you may be able to reset the alarm with your BIOS.
185
187 If you see `(beep)' beside any sensor reading, that just means that
188 your system is configured to issue an audio warning from the mother‐
189 board if an alarm is signalled on that sensor.
190
192 Sensord(8) provides support for storing sensor readings in a round-
193 robin database. This may be a useful alternative to the use of sys‐
194 log(3).
195 Round-robin databases are constant-size databases that can be used to
197 store, for example, a week's worth of sensor readings. Subsequent read‐
198 ings stored in the database will overwrite readings that are over a
199 week old. This capability is extremely useful because it allows useful
200 information to be stored in an easily-accessible manner for a useful
201 length of time, without the burden of ever-growing log files.
202 The rrdtool(1) utility and its associated library provide the basic
204 framework for the round-robin database beneath sensord(8). In addi‐
205 tion, the rrdcgi(1) and rrdgraph(1) utilities provide support for gen‐
206 erating graphs of these data for display in a Web page.
207 If you wish to use the default configuration of round-robin database,
209 which holds one week of sensor readings at five-minute intervals, then
210 simply start sensord(8) and specify where you want the database stored.
211 It will automatically be created and configured using these default
212 parameters.
213 If you wish readings to be stored for a longer period, or want multiple
215 readings to be averaged into each database entry, then you must manu‐
216 ally create and configure the database before starting sensord(8).
217 Consult the rrdcreate(1) manual for details. Note that the database
218 must match exactly the names and order of sensors read by sensord(8).
219 It is recommended that you create the default database and then use
220 rrdinfo(1) to obtain this information, and/or rrdtune(1) to change it.
221 After creating the round-robin database, you must then configure your
223 Web server to display the sensor information. This assumes that you
224 have a Web server preconfigured and functioning on your machine. Sen‐
225 sord(8) provides a command-line option --rrd-cgi to generate a basic
226 CGI script to display these graphs; you can then customize this script
227 as desired. Consult the rrdcgi(1) manual for details. This CGI script
228 requires a world-writable, Web-accessible directory into which to write
229 the graphs that it generates.
230 An example of how to set up Web-accessible graphs of recent sensor
232 readings follows:
233 sensord --log-interval 0 \
235 --load-average \
236 --rrd-file /var/log/sensord.rrd
237 Here, we start sensord(8) and configure it to store readings in a
239 round-robin database; note that we disable logging of sensor readings
240 to syslog(3), and enable logging of the load average.
241 mkdir /var/www/sensord
243 chown www-data:staff /var/www/sensord
244 chmod a=rwxs /var/www/sensord
245 Here, we create a world-writable, Web-accessible directory in which
247 graphs will be stored; we set the ownership and permissions on this
248 directory appropriately. You will have to determine the location and
249 ownership that is appropriate for your machine.
250 sensord --load-average \
252 --rrd-file /var/log/sensord.rrd \
253 --rrd-cgi /var/www/sensord \
254 > /usr/lib/cgi-bin/sensord.cgi
255 chmod a+rx /usr/lib/cgi-bin/sensord.cgi
256 Here, we create a CGI script that will display sensor readings from the
258 database. You must specify the location of the round-robin database,
259 the location of the directory where the images should be stored, and
260 whether you want the load average displayed. The --rrd-cgi command-line
261 parameter causes sensord(8) to display a suitable CGI script on stdout
262 and then to exit. You will need to write this script to the CGI bin
263 directory of your Web server, and edit the script if the image direc‐
264 tory you chose is not the `/sensord/' directory of your Web server.
265 Finally, you should be able to view your sensor readings from the URL
267 `http://localhost/cgi-bin/sensord.cgi'.
268
270 It is expected that all required sensor modules are loaded prior to
271 this daemon being started. This can either be achieved with a system
272 specific module loading scheme (e.g., listing the required modules in
273 the file `/etc/modules' under Debian) or with explicit modprobe(1) com‐
274 mands in an init script before loading the daemon.
275 For example, a `sensord' initialization script might contain (among
277 others) the following commands:
278 # Sample init.d scriptlet
280 echo -n "Loading AMD756 module: "
281 modprobe i2c-amd756 || { echo Fail. ; exit 1 ; }
282 echo OK.
283 echo -n "Loading W83781D module: "
284 modprobe w83781d || { echo Fail. ; exit 1 ; }
285 echo OK.
286 echo -n "Starting sensord: "
287 daemon sensord
288 Ignore the platform-specific shell functions; the general idea should
290 be fairly clear.
291
293 Errors encountered by this daemon are logged to syslogd(8) after which
294 the daemon will exit.
295
297 Round-robin database support doesn't cope with multiple sensor chips
298 having duplicate sensor labels.
299
301 /etc/sensors.conf
302 The system-wide libsensors(3) configuration file. See sen‐
303 sors.conf(5) for further details.
304 /etc/syslog.conf
305 The system-wide syslog(3) / syslogd(8) configuration file. See
306 syslog.conf(5) for further details.
307
309 lm_sensors-2.x
310
312 sensors.conf(5)
313
315 Sensord was written by Merlin Hughes <merlin@merlin.org>. Chip-specific
316 formatting code was ripped from sensors which was written by Frodo
317 Looijaard <frodol@dds.nl>. Basics of round-robin databases were misap‐
318 propriated from Mark D. Studebaker.
319 October 2007 sensord(8)