sensord(8)						    Linux System Administration 						sensord(8)

NAME

       sensord - Sensor information logging daemon.

SYNOPSIS

       sensord [ options ] [ chips ]

DESCRIPTION

       Sensord	is  a  daemon  that can be used to periodically log sensor readings from hardware health-monitoring chips to syslog(3) or a round-
       robin database (RRD) and to alert when a sensor alarm is signalled; for example, if a fan fails, a temperature limit is exceeded, etc.

OPTIONS

       -i, --interval time
	      Specify the interval between scanning for sensor alarms; the default is to scan every minute.

	      The time should be specified as a raw integer (seconds) or with a suffix `s' for seconds, `m' for minutes  or  `h'  for  hours;  for
	      example, the default interval is `60' or `1m'.

	      Specify an interval of zero to suppress scanning explicitly for alarms.

       -l, --log-interval time
	      Specify the interval between logging all sensor readings; the default is to log all readings every half hour.

	      The time is specified as before; e.g., `30m'.

	      Specify an interval of zero to suppress logging of regular sensor readings.

       -t, --rrd-interval time
	      Specify  the  interval  between logging all sensor readings to a round-robin database; the default is to log all readings every five
	      minutes if a round-robin database is configured.

	      The time is specified as before; e.g., `5m'.

       -T, --rrd-no-average
	      Specify that the round-robin database should not be averaged.

       -r, --rrd-file file
	      Specify a round-robin database into which to log all sensor readings; e.g., `/var/log/sensord.rrd'. This database will be created if
	      it does not exist. By default, no round-robin database is used.

	      See the section ROUND ROBIN DATABASES below for more details.

       -c, --config-file file
	      Specify a libsensors(3) configuration file. If no file is specified, the libsensors default configuration file is used.

       -p, --pid-file file
	      Specify  what PID file to write; the default is to write the file `/var/run/sensord.pid'. You should always specify an absolute path
	      here. The file is removed when the daemon exits.

       -f, --syslog-facility facility
	      Specify the syslog(3) facility to use when logging sensor readings and alarms; the default is to use daemon.

	      Other possible facilities include local0 through local7, and user.

       -g, --rrd-cgi directory
	      Prints out a sample rrdcgi(1) CGI script that can be used to display graphs of recent sensor information in a Web page,  and  exits.
	      You  must  specify  the world-writable, Web-accessible directory where the graphs should be stored; the CGI script assumes that this
	      will be accessed under the `/sensord/' directory on the Webserver. See the section ROUND ROBIN DATABASES below for more details.

       -a, --load-average
	      Include the load average in the RRD database. You should also specify this flag when you create the CGI script.

       -d, --debug
	      Prints a small amount of additional debugging information.

       -h, --help
	      Prints a help message and exits.

       -v, --version
	      Displays the program version and exits.

CHIPS

       To restrict the devices that are scanned by this daemon, you may optionally specify a list of chip names. By default, all  available  chips
       are scanned.

       A typical chip name would be `w83782d-*' (you may want to escape the `*' for your shell) which would scan any W83782D chips on any bus. See
       sensors.conf(5) for more details. Another option is to simply not load the sensor modules for chips in which you have no interest.

SIGNALS

       Upon receipt of a SIGTERM (see signal(7) for details) this daemon should gracefully shut down.

       Upon receipt of a SIGHUP, this daemon will rescan the kernel interface for chips and features,  and  reload  the  libsensors  configuration
       file.

LOGGING

       All messages from this daemon are logged to syslog(3) under the program name `sensord' and facility daemon, or whatever is specified on the
       command line.

       Regular sensor readings are logged at the level info.  Alarms are logged at the level alert.  Inconsequential status messages are logged at
       the minimum level, debug, when debugging is enabled.

       You can use an appropriate `/etc/syslog.conf' file to direct these messages in a useful manner. See syslog.conf(5) for full details. Assum-
       ing you set the logging facility to local4, the following is a sample configuration:

	      # Sample syslog.conf entries
	      *.info;...;local4.none;local4.warn  /var/log/messages
	      local4.info			 -/var/log/sensors
	      local4.alert			  /dev/console
	      local4.alert			  *

       The first line ensures that regular sensor readings do not clutter `/var/log/messages'; we first say `local4.none'  to  eliminate  informa-
       tional messages; then `local4.warn' to enable warnings and above. The second line says to log all regular sensor readings to `/var/log/sen-
       sors'; the leading hyphen `-' means that this file is not flushed after every message. The final two lines ensure that alarms  are  printed
       to the system console as well as to all connected users (in addition to `/var/log/messages' and `/var/log/sensors').

LOG ROTATION

       On  a  typical  system with a good sensor chip, expect about 2KB per sensor reading in the log file. This works out at about 3MB per month.
       You should be rotating your syslog files anyway, but just to be sure you'll want to use something  like	logrotate(8)  or  equivalent.  You
       might, for example, want an entry in `/etc/logrotate.d/syslog' containing:

	      # Sample logrotate.d entry
	      /var/log/sensors {
		  postrotate
		      /usr/sbin/killall -HUP syslogd
		  endscript
	      }

       Note, of course, that you want to restart syslogd(8) and not sensord(8)

ALARMS

       Alarms  generally indicate a critical condition; for example, a fan failure or an unacceptable temperature or voltage. However, some sensor
       chips do not support alarms, while others are incorrectly configured and may signal alarms incorrectly.

       Note that some drivers may lack support for alarm reporting even though the chips they support do have alarms. As  of  Linux  2.6.23,  many
       drivers still don't report alarms in a format suitable for libsensors 3.

BEEPS

       If  you	see  `(beep)' beside any sensor reading, that just means that your system is configured to issue an audio warning from the mother-
       board if an alarm is signalled on that sensor.

ROUND ROBIN DATABASES

       Sensord(8) provides support for storing sensor readings in a round-robin database. This may be a useful alternative  to	the  use  of  sys-
       log(3).

       Round-robin  databases  are  constant-size  databases that can be used to store, for example, a week's worth of sensor readings. Subsequent
       readings stored in the database will overwrite readings that are over a week old. This capability is extremely  useful  because	it  allows
       useful information to be stored in an easily-accessible manner for a useful length of time, without the burden of ever-growing log files.

       The  rrdtool(1)	utility  and its associated library provide the basic framework for the round-robin database beneath sensord(8).  In addi-
       tion, the rrdcgi(1) and rrdgraph(1) utilities provide support for generating graphs of these data for display in a Web page.

       If you wish to use the default configuration of round-robin database, which holds one week of sensor  readings  at  five-minute	intervals,
       then  simply  start  sensord(8) and specify where you want the database stored. It will automatically be created and configured using these
       default parameters.

       If you wish readings to be stored for a longer period, or want multiple readings to be averaged into each database  entry,  then  you  must
       manually create and configure the database before starting sensord(8).  Consult the rrdcreate(1) manual for details. Note that the database
       must match exactly the names and order of sensors read by sensord(8).  It is recommended that you create the default database and then  use
       rrdinfo(1) to obtain this information, and/or rrdtune(1) to change it.

       After  creating	the round-robin database, you must then configure your Web server to display the sensor information. This assumes that you
       have a Web server preconfigured and functioning on your machine.  Sensord(8) provides a command-line option --rrd-cgi to generate  a  basic
       CGI  script  to	display  these	graphs; you can then customize this script as desired.	Consult the rrdcgi(1) manual for details. This CGI
       script requires a world-writable, Web-accessible directory into which to write the graphs that it generates.

       An example of how to set up Web-accessible graphs of recent sensor readings follows:

	      sensord --log-interval 0 
		--load-average 
		--rrd-file /var/log/sensord.rrd

       Here, we start sensord(8) and configure it to store readings in a round-robin database; note that we disable logging of sensor readings	to
       syslog(3), and enable logging of the load average.

	      mkdir /var/www/sensord
	      chown www-data:staff /var/www/sensord
	      chmod a=rwxs /var/www/sensord

       Here,  we  create  a  world-writable, Web-accessible directory in which graphs will be stored; we set the ownership and permissions on this
       directory appropriately. You will have to determine the location and ownership that is appropriate for your machine.

	      sensord --load-average 
		--rrd-file /var/log/sensord.rrd 
		--rrd-cgi /var/www/sensord 
		> /usr/lib/cgi-bin/sensord.cgi
	      chmod a+rx /usr/lib/cgi-bin/sensord.cgi

       Here, we create a CGI script that will display sensor readings from the database.  You must specify the location of the	round-robin  data-
       base,  the location of the directory where the images should be stored, and whether you want the load average displayed. The --rrd-cgi com-
       mand-line parameter causes sensord(8) to display a suitable CGI script on stdout and then to exit. You will need to write  this	script	to
       the CGI bin directory of your Web server, and edit the script if the image directory you chose is not the `/sensord/' directory of your Web
       server.

       Finally, you should be able to view your sensor readings from the URL `http://localhost/cgi-bin/sensord.cgi'.

MODULES

       It is expected that all required sensor modules are loaded prior to this daemon being started. This can either be achieved  with  a  system
       specific  module  loading  scheme (e.g., listing the required modules in the file `/etc/modules' under Debian) or with explicit modprobe(1)
       commands in an init script before loading the daemon.

       For example, a `sensord' initialization script might contain (among others) the following commands:

	      # Sample init.d scriptlet
	      echo -n "Loading AMD756 module: "
	      modprobe i2c-amd756 || { echo Fail. ; exit 1 ; }
	      echo OK.
	      echo -n "Loading W83781D module: "
	      modprobe w83781d || { echo Fail. ; exit 1 ; }
	      echo OK.
	      echo -n "Starting sensord: "
	      daemon sensord

       Ignore the platform-specific shell functions; the general idea should be fairly clear.

ERRORS

       Errors encountered by this daemon are logged to syslogd(8) after which the daemon will exit.

BUGS

       Round-robin database support doesn't cope with multiple sensor chips having duplicate sensor labels.

FILES

       /etc/sensors3.conf
       /etc/sensors.conf
	      The system-wide libsensors(3) configuration file. See sensors.conf(5) for further details.
       /etc/syslog.conf
	      The system-wide syslog(3) / syslogd(8) configuration file. See syslog.conf(5) for further details.

SEE ALSO

       sensors.conf(5)

AUTHORS

       Sensord was written by Merlin Hughes <merlin@merlin.org>. Basics of round-robin databases were misappropriated from Mark D. Studebaker.

lm-sensors 3							   October 2007 							sensord(8)