Man Linux: Main Page and Category List


       collectd-exec - Documentation of collectd's "exec plugin"


         # See collectd.conf(5)
         LoadPlugin exec
         # ...
         <Plugin exec>
           Exec "myuser:mygroup" "myprog"
           Exec "otheruser" "/path/to/another/binary" "arg0" "arg1"
           NotificationExec "user" "/usr/lib/collectd/exec/handle_notification"


       The "exec plugin" forks of an executable either to receive values or to
       dispatch notifications to the outside world. The syntax of the
       configuration is explained in collectd.conf(5) but summarized in the
       above synopsis.

       If you want/need better performance or more functionality you should
       take a long look at the "perl plugin", collectd-perl(5).


       There are currently two types of executables that can be executed by
       the "exec plugin":

           These programs are forked and values that it writes to "STDOUT" are
           read back.  The executable is forked in a fashion similar to init:
           It is forked once and not again until it exits. If it exited, it
           will be forked again after at most Interval seconds. It is
           perfectly legal for the executable to run for a long time and
           continuously write values to "STDOUT".

           See "EXEC DATA FORMAT" below for a description of the output format
           expected from these programs.

           Warning: If the executable only writes one value and then exits I
           will be executed every Interval seconds. If Interval is short (the
           default is 10 seconds) this may result in serious system load.

           The program is forked once for each notification that is handled by
           the daemon.  The notification is passed to the program on "STDIN"
           in a fashion similar to HTTP-headers. In contrast to programs
           specified with "Exec" the execution of this program is not
           serialized, so that several instances of this program may run at
           once if multiple notifications are received.

           See "NOTIFICATION DATA FORMAT" below for a description of the data
           passed to these programs.


       The forked executable is expected to print values to "STDOUT". The
       expected format is as follows:

           Each line beginning with a "#" (hash mark) is ignored.

       PUTVAL Identifier [OptionList] Valuelist
           Submits one or more values (identified by Identifier, see below) to
           the daemon which will dispatch it to all it's write-plugins.

           An Identifier is of the form "host/plugin-instance/type-instance"
           with both instance-parts being optional. If they're omitted the
           hyphen must be omitted, too. plugin and each instance-part may be
           chosen freely as long as the tuple (plugin, plugin instance, type
           instance) uniquely identifies the plugin within collectd. type
           identifies the type and number of values (i. e. data-set) passed to
           collectd. A large list of predefined data-sets is available in the
           types.db file. See types.db(5) for a description of the format of
           this file.

           The OptionList is an optional list of Options, where each option is
           a key-value-pair. A list of currently understood options can be
           found below, all other options will be ignored. Values that contain
           spaces must be quoted with double quotes.

           Valuelist is a colon-separated list of the time and the values,
           each either an integer if the data-source is a counter, or a double
           if the data-source is of type "gauge". You can submit an undefined
           gauge-value by using U. When submitting U to a counter the behavior
           is undefined. The time is given as epoch (i. e. standard UNIX

           You can mix options and values, but the order is important: Options
           only effect following values, so specifying an option as last field
           is allowed, but useless. Also, an option applies to all following
           values, so you don't need to re-set an option over and over again.

           The currently defined Options are:

               Gives the interval in which the data identified by Identifier
               is being collected.

           Please note that this is the same format as used in the unixsock
           plugin, see collectd-unixsock(5). There's also a bit more
           information on identifiers in case you're confused.

           Since examples usually let one understand a lot better, here are

             leeloo/cpu-0/cpu-idle N:2299366
             alice/interface/if_octets-eth0 interval=10 1180647081:421465:479194

           Since this action was the only one supported with older versions of
           the "exec plugin" all lines were treated as if they were prefixed
           with PUTVAL. This is still the case to maintain backwards
           compatibility but deprecated.

       PUTNOTIF [OptionList] message=Message
           Submits a notification to the daemon which will then dispatch it to
           all plugins which have registered for receiving notifications.

           The PUTNOTIF if followed by a list of options which further
           describe the notification. The message option is special in that it
           will consume the rest of the line as its value. The message,
           severity, and time options are mandatory.

           Valid options are:

           message=Message (REQUIRED)
               Sets the message of the notification. This is the message that
               will be made accessible to the user, so it should contain some
               useful information. As with all options: If the message
               includes spaces, it must be quoted with double quotes. This
               option is mandatory.

           severity=failure|warning|okay (REQUIRED)
               Sets the severity of the notification. This option is

           time=Time (REQUIRED)
               Sets the time of the notification. The time is given as
               "epoch", i. e. as seconds since January 1st, 1970, 00:00:00.
               This option is mandatory.

               These "associative" options establish a relation between this
               notification and collected performance data. This connection is
               purely informal, i. e. the daemon itself doesn't do anything
               with this information. However, websites or GUIs may use this
               information to place notifications near the affected graph or
               table. All the options are optional, but plugin_instance
               without plugin or type_instance without type doesn't make much
               sense and should be avoided.

       Please note that this is the same format as used in the unixsock
       plugin, see collectd-unixsock(5).

       When collectd exits it sends a SIGTERM to all still running child-
       processes upon which they have to quit.


       The notification executables receive values rather than providing them.
       In fact, after the program is started "STDOUT" is connected to

       The data is passed to the executables over "STDIN" in a format very
       similar to HTTP: At first there is a "header" with one line per field.
       Every line consists of a field name, ended by a colon, and the
       associated value until end-of-line.  The "header" is ended by two
       newlines immediately following another, i. e. an empty line. The rest,
       basically the "body", is the message of the notification.

       The following is an example notification passed to a program:

         Severity: FAILURE
         Time: 1200928930
         This is a test notification to demonstrate the format

       The following header files are currently used. Please note, however,
       that you should ignore unknown header files to be as forward-compatible
       as possible.

           Severity of the notification. May either be FAILURE, WARNING, or

           The time in epoch, i. e. as seconds since 1970-01-01 00:00:00 UTC.

           Identification of the performance data this notification is
           associated with.  All of these fields are optional because
           notifications do not need to be associated with a certain value.


       The following environment variables are set by the plugin before
       calling exec:

           Value of the global interval setting.

           Hostname used by collectd to dispatch local values.


       Though the interface is far from perfect, there are tons of plugins for
       Nagios.  You can use these plugins with collectd by using a simple
       transition layer, "exec-nagios.px", which is shipped with the collectd
       distribution in the "contrib/" directory. It is a simple Perl script
       that comes with embedded documentation. To see it, run the following

         perldoc exec-nagios.px

       This script expects a configuration file, "exec-nagios.conf". You can
       find an example in the "contrib/" directory, too.

       Even a simple mechanism to submit "performance data" to collectd is
       implemented. If you need a more sophisticated setup, please rewrite the
       plugin to make use of collectd's more powerful interface.


       o   The user, the binary is executed as, may not have root privileges,
           i. e.  must have an UID that is non-zero. This is for your own


       collectd(1), collectd.conf(5), collectd-perl(5), collectd-unixsock(5),
       fork(2), exec(3)


       Florian Forster <>