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upstart-file-bridge(8)					upstart-file-bridge(8)

NAME
       upstart-file-bridge - Bridge between Upstart and inotify

SYNOPSIS
       upstart-file-bridge [OPTIONS]...

DESCRIPTION
       upstart-file-bridge  receives information about kernel file events that
       inotify(7) has received and creates init(8) events for them.

       Supported events exposed to Upstart allow jobs to detect creation, mod‐
       ification and deletion. See file-event(7) for further details.

       The  bridge works by querying the init(8) daemon at bridge startup time
       to determine a list of all jobs whose start on or  stop	on  conditions
       reference  the  file event. Further, the bridge arranges to be notified
       automatically when new jobs are created such that any  subsequent  jobs
       which reference the file event are also handled (as are job deletions).

       See inotify(7) and for further details.

OPTIONS
       --daemon
	      Detach and run in the background.

       --debug
	      Enable debugging output.

       --help Show brief usage summary.

       --user User-session  mode:  connect  to	Upstart	 via  the user session
	      rather than over the D-Bus system bus.

       --verbose
	      Enable verbose output.

JOB ENVIRONMENT VARIABLES
       FILE   Path to file to watch. When run without --user, this must be  an
	      absolute	path.  If  --user  is specified, certain relative path
	      types are supported:

	      · If the path begins with '~/', the value will  be  expanded  as
		would  be performed by a shell for matching purposes (although
		when the event is emitted, the original value will be used).

	      · If the path begins with './', '.' will be assumed  to  be  the
		users home directory.

	      · In  all	 other scenarios, if the path does not begin with '/',
		it will be assumed to represent a file below  the  users  home
		directory.

	      If  the  path ends with a slash, it is considered to be a direc‐
	      tory which changes the match behaviour (see below).

	      If the path is not a directory, the file (but not the directory)
	      portion of the path may contain wildcard matches. See fnmatch(3)
	      and glob(7) for further details.

       EVENT  Event relating to FILE that job is interested in. If this	 vari‐
	      able  is	specified  the	value must be set to create, modify or
	      delete depending on what type of file event the  job  is	inter‐
	      ested  in.  If  FILE is not specified, the bridge will watch for
	      all types and set this variable to the  appropriate  value  when
	      emitting the event.

WATCH TYPE BEHAVIOUR
       The  bridge  emits events depending not only on the value of EVENT, but
       also on the entity specified by FILE:

   File
       An event will be emitted when the named file is	created,  modified  or
       deleted	depending  on  the  value of EVENT. If EVENT is not specified,
       react to creation, modification and deletion.

       If the file already exists when the job is registered, and EVENT either
       specifies  create  or  the variable is not specified, the event will be
       emitted.

   Directory
       An event will be emitted when the named directory is created,  modified
       (files within it are created, modified or deleted) or deleted depending
       on the value of EVENT. If EVENT is not specified,  react	 to  creation,
       modification and deletion.

       If  the	directory already exists when the job is registered, and EVENT
       either specifies create or the variable is  not	specified,  the	 event
       will be emitted.

   Glob
       One  event will be emitted per match when the glob wildcard matches any
       files in the directory part is created, modified or deleted,  depending
       on  the	value  of EVENT. If EVENT is not specified, react to creation,
       modification and deletion.

       If any matches already exist when the  job  is  registered,  and	 EVENT
       either  specifies  create or the variable is not specified, events will
       be emitted.

NOTES
       ·   A single instance of the bridge may be run at the system level, but
	   multiple  further instances may be run per user session instance by
	   using the --user.

       ·   All job conditions specifying the file event are multi-shot: if the
	   same	 file  event  occurs  multiple	times, the bridge will emit an
	   Upstart event each time.

LIMITATIONS
       ·   Since the bridge currently uses inotify(7), it is  subject  to  the
	   same	 limitations;  namely that recursive watches cannot be created
	   reliably in all circumstances. As such, pathological scenarios such
	   as deep directory trees being created and then quickly removed can‐
	   not be handled reliably. The following provides advice to  minimise
	   unexpected behaviour:

	   ·   Attempt	to  only  watch	 for  files to be created, modified or
	       deleted in directories that are guaranteed to already exist  at
	       the time the job is registered by the bridge.

	   ·   If the system cannot guarantee that the directory will exist at
	       job registration time, arrange for the directory to be  created
	       by an Upstart job before the bridge itself starts.

	   ·   In  user	 session  mode, if a job specifies a file to watch for
	       and that file is created but inaccessible to the	 user  running
	       the bridge, no event will be emitted.

       ·   Tilde  expansion  is	 only  supported for the current user; that is
	   '~otheruser' will not work.

AUTHOR
       Written by James Hunt <james.hunt@canonical.com>

BUGS
       Report bugs at <https://launchpad.net/ubuntu/+source/upstart/+bugs>

COPYRIGHT
       Copyright © 2013 Canonical Ltd.

       This is free software; see the source for copying conditions.  There is
       NO  warranty;  not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
       PURPOSE.

SEE ALSO
       init(5) init(8) inotify(7) file-event(7)

upstart				  2013-03-11		upstart-file-bridge(8)
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