= Daemons =

'''Daemons''' are server programs that normally run continuously.
Your project's daemons are described in its [ProjectConfigFile config.xml] file, with elements of the form:

{{{
<daemon>
  <cmd> feeder -d 3 </cmd>
  [ <host>host.domain.name</host> ]
  [ <disabled> 0|1 </disabled> ]
  [ <silent_start> 0|1 </silent_start> ]
  [ <output>filename</output> ]
  [ <pid_file>filename</pid_file> ]
</daemon>
<daemon>
...
</daemon>
}}}

 '''cmd'''::
	The command used to start the daemon. Must be a program in the project's `bin/` directory.
 '''host'''::
	Specifies the host on which the daemon should run. The default is the project's main host, as specified in config.xml.
 '''disabled'''::
	If set to 1, ignore this daemon. Note: <disabled/> won't work; you must specify a number.
 '''silent_start'''::
        If set to 1, don't print a message at project startup about this daemon. Note: <silent_start/> won't work; you must specify a number.
 '''output'''::
	Name of output file (in the `log_HOSTNAME` directory). Defaults to the program name followed by '.log'. If you're running multiple instances of a daemon on one host, you must specify this.
 '''pid_file'''::
	Name of file used to store the process ID (in the `pid_HOSTNAME` directory). Defaults to the program name followed by '.pid'. If you're running multiple instances of a daemon on one host, you must specify this.

Daemons are executed in a directory '''tmp_hostname/''' (not '''bin/''').
Daemons are started when you run the [StartTool bin/start] script,
and killed (by a SIGHUP signal) when you run [StartTool bin/stop].

Typically, this mechanism is used to run [BackendPrograms work handling daemons].
Projects that use trickle-up messages will also need to have a [TrickleMessages trickle-up handler].