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
20 -i, --interval time
21 Specify the interval between scanning for sensor alarms; the
22 default is to scan every minute.
23 The time should be specified as a raw integer (seconds) or with
25 a suffix `s' for seconds, `m' for minutes or `h' for hours; for
26 example, the default interval is `60' or `1m'.
27 Specify an interval of zero to suppress scanning explicitly for
29 alarms.
30 -l, --log-interval time
32 Specify the interval between logging all sensor readings; the
33 default is to log all readings every half hour.
34 The time is specified as before; e.g., `30m'.
36 Specify an interval of zero to suppress logging of regular sen‐
38 sor readings.
39 -t, --rrd-interval time
41 Specify the interval between logging all sensor readings to a
42 round-robin database; the default is to log all readings every
43 five minutes if a round-robin database is configured.
44 The time is specified as before; e.g., `5m'.
46 -T, --rrd-no-average
48 Specify that the round-robin database should not be averaged.
49 -r, --rrd-file file
52 Specify a round-robin database into which to log all sensor
53 readings; e.g., `/var/log/sensord.rrd'. This database will be
54 created if it does not exist. By default, no round-robin data‐
55 base is used.
56 See the section ROUND ROBIN DATABASES below for more details.
58 -c, --config-file file
60 Specify a libsensors(3) configuration file. If no file is speci‐
61 fied, the libsensors default configuration file is used.
62 -p, --pid-file file
65 Specify what PID file to write; the default is to write the file
66 `/var/run/sensord.pid'. You should always specify an absolute
67 path here. The file is removed when the daemon exits.
68 -f, --syslog-facility facility
70 Specify the syslog(3) facility to use when logging sensor read‐
71 ings and alarms; the default is to use daemon.
72 Other possible facilities include local0 through local7, and
74 user.
75 -g, --rrd-cgi directory
77 Prints out a sample rrdcgi(1) CGI script that can be used to
78 display graphs of recent sensor information in a Web page, and
79 exits. You must specify the world-writable, Web-accessible
80 directory where the graphs should be stored; the CGI script
81 assumes that this will be accessed under the `/sensord/' direc‐
82 tory on the Webserver. See the section ROUND ROBIN DATABASES
83 below for more details.
84 -a, --load-average
86 Include the load average in the RRD database. You should also
87 specify this flag when you create the CGI script.
88 -d, --debug
90 Prints a small amount of additional debugging information.
91 -h, --help
93 Prints a help message and exits.
94 -v, --version
96 Displays the program version and exits.
97
99 To restrict the devices that are scanned by this daemon, you may
100 optionally specify a list of chip names. By default, all available
101 chips are scanned.
102 A typical chip name would be `w83782d-*' (you may want to escape the
104 `*' for your shell) which would scan any W83782D chips on any bus. See
105 sensors.conf(5) for more details. Another option is to simply not load
106 the sensor modules for chips in which you have no interest.
107
109 Upon receipt of a SIGTERM (see signal(7) for details) this daemon
110 should gracefully shut down.
111 Upon receipt of a SIGHUP, this daemon will rescan the kernel interface
113 for chips and features, and reload the libsensors configuration file.
114
116 All messages from this daemon are logged to syslog(3) under the program
117 name `sensord' and facility daemon, or whatever is specified on the
118 command line.
119 Regular sensor readings are logged at the level info. Alarms are
121 logged at the level alert. Inconsequential status messages are logged
122 at the minimum level, debug, when debugging is enabled.
123 You can use an appropriate `/etc/syslog.conf' file to direct these mes‐
125 sages in a useful manner. See syslog.conf(5) for full details. Assuming
126 you set the logging facility to local4, the following is a sample con‐
127 figuration:
128 # Sample syslog.conf entries
130 *.info;...;local4.none;local4.warn /var/log/messages
131 local4.info -/var/log/sensors
132 local4.alert /dev/console
133 local4.alert *
134 The first line ensures that regular sensor readings do not clutter
136 `/var/log/messages'; we first say `local4.none' to eliminate informa‐
137 tional messages; then `local4.warn' to enable warnings and above. The
138 second line says to log all regular sensor readings to `/var/log/sen‐
139 sors'; the leading hyphen `-' means that this file is not flushed after
140 every message. The final two lines ensure that alarms are printed to
141 the system console as well as to all connected users (in addition to
142 `/var/log/messages' and `/var/log/sensors').
143
145 On a typical system with a good sensor chip, expect about 2KB per sen‐
146 sor reading in the log file. This works out at about 3MB per month. You
147 should be rotating your syslog files anyway, but just to be sure you'll
148 want to use something like logrotate(8) or equivalent. You might, for
149 example, want an entry in `/etc/logrotate.d/syslog' containing:
150 # Sample logrotate.d entry
152 /var/log/sensors {
153 postrotate
154 /usr/sbin/killall -HUP syslogd
155 endscript
156 }
157 Note, of course, that you want to restart syslogd(8) and not sensord(8)
159
161 Alarms generally indicate a critical condition; for example, a fan
162 failure or an unacceptable temperature or voltage. However, some sensor
163 chips do not support alarms, while others are incorrectly configured
164 and may signal alarms incorrectly.
165 Note that some drivers may lack support for alarm reporting even though
167 the chips they support do have alarms. As of Linux 2.6.23, many drivers
168 still don't report alarms in a format suitable for libsensors 3.
169
172 If you see `(beep)' beside any sensor reading, that just means that
173 your system is configured to issue an audio warning from the mother‐
174 board if an alarm is signalled on that sensor.
175
177 Sensord(8) provides support for storing sensor readings in a round-
178 robin database. This may be a useful alternative to the use of sys‐
179 log(3).
180 Round-robin databases are constant-size databases that can be used to
182 store, for example, a week's worth of sensor readings. Subsequent read‐
183 ings stored in the database will overwrite readings that are over a
184 week old. This capability is extremely useful because it allows useful
185 information to be stored in an easily-accessible manner for a useful
186 length of time, without the burden of ever-growing log files.
187 The rrdtool(1) utility and its associated library provide the basic
189 framework for the round-robin database beneath sensord(8). In addi‐
190 tion, the rrdcgi(1) and rrdgraph(1) utilities provide support for gen‐
191 erating graphs of these data for display in a Web page.
192 If you wish to use the default configuration of round-robin database,
194 which holds one week of sensor readings at five-minute intervals, then
195 simply start sensord(8) and specify where you want the database stored.
196 It will automatically be created and configured using these default
197 parameters.
198 If you wish readings to be stored for a longer period, or want multiple
200 readings to be averaged into each database entry, then you must manu‐
201 ally create and configure the database before starting sensord(8).
202 Consult the rrdcreate(1) manual for details. Note that the database
203 must match exactly the names and order of sensors read by sensord(8).
204 It is recommended that you create the default database and then use
205 rrdinfo(1) to obtain this information, and/or rrdtune(1) to change it.
206 After creating the round-robin database, you must then configure your
208 Web server to display the sensor information. This assumes that you
209 have a Web server preconfigured and functioning on your machine. Sen‐
210 sord(8) provides a command-line option --rrd-cgi to generate a basic
211 CGI script to display these graphs; you can then customize this script
212 as desired. Consult the rrdcgi(1) manual for details. This CGI script
213 requires a world-writable, Web-accessible directory into which to write
214 the graphs that it generates.
215 An example of how to set up Web-accessible graphs of recent sensor
217 readings follows:
218 sensord --log-interval 0 \
220 --load-average \
221 --rrd-file /var/log/sensord.rrd
222 Here, we start sensord(8) and configure it to store readings in a
224 round-robin database; note that we disable logging of sensor readings
225 to syslog(3), and enable logging of the load average.
226 mkdir /var/www/sensord
228 chown www-data:staff /var/www/sensord
229 chmod a=rwxs /var/www/sensord
230 Here, we create a world-writable, Web-accessible directory in which
232 graphs will be stored; we set the ownership and permissions on this
233 directory appropriately. You will have to determine the location and
234 ownership that is appropriate for your machine.
235 sensord --load-average \
237 --rrd-file /var/log/sensord.rrd \
238 --rrd-cgi /var/www/sensord \
239 > /usr/lib/cgi-bin/sensord.cgi
240 chmod a+rx /usr/lib/cgi-bin/sensord.cgi
241 Here, we create a CGI script that will display sensor readings from the
243 database. You must specify the location of the round-robin database,
244 the location of the directory where the images should be stored, and
245 whether you want the load average displayed. The --rrd-cgi command-line
246 parameter causes sensord(8) to display a suitable CGI script on stdout
247 and then to exit. You will need to write this script to the CGI bin
248 directory of your Web server, and edit the script if the image direc‐
249 tory you chose is not the `/sensord/' directory of your Web server.
250 Finally, you should be able to view your sensor readings from the URL
252 `http://localhost/cgi-bin/sensord.cgi'.
253
255 It is expected that all required sensor modules are loaded prior to
256 this daemon being started. This can either be achieved with a system
257 specific module loading scheme (e.g., listing the required modules in
258 the file `/etc/modules' under Debian) or with explicit modprobe(1) com‐
259 mands in an init script before loading the daemon.
260 For example, a `sensord' initialization script might contain (among
262 others) the following commands:
263 # Sample init.d scriptlet
265 echo -n "Loading AMD756 module: "
266 modprobe i2c-amd756 || { echo Fail. ; exit 1 ; }
267 echo OK.
268 echo -n "Loading W83781D module: "
269 modprobe w83781d || { echo Fail. ; exit 1 ; }
270 echo OK.
271 echo -n "Starting sensord: "
272 daemon sensord
273 Ignore the platform-specific shell functions; the general idea should
275 be fairly clear.
276
278 Errors encountered by this daemon are logged to syslogd(8) after which
279 the daemon will exit.
280
282 Round-robin database support doesn't cope with multiple sensor chips
283 having duplicate sensor labels.
284
286 /etc/sensors3.conf
287 /etc/sensors.conf
288 The system-wide libsensors(3) configuration file. See sen‐
289 sors.conf(5) for further details.
290 /etc/syslog.conf
291 The system-wide syslog(3) / syslogd(8) configuration file. See
292 syslog.conf(5) for further details.
293
296 sensors.conf(5)
297
299 Sensord was written by Merlin Hughes <merlin@merlin.org>. Basics of
300 round-robin databases were misappropriated from Mark D. Studebaker.
301lm-sensors 3 October 2007 sensord(8)