Inotify2(3pm)						User Contributed Perl Documentation					     Inotify2(3pm)

NAME

       Linux::Inotify2 - scalable directory/file change notification

SYNOPSIS

   Callback Interface
	use Linux::Inotify2;

	# create a new object
	my $inotify = new Linux::Inotify2
	   or die "unable to create new inotify object: $!";

	# add watchers
	$inotify->watch ("/etc/passwd", IN_ACCESS, sub {
	   my $e = shift;
	   my $name = $e->fullname;
	   print "$name was accessed
" if $e->IN_ACCESS;
	   print "$name is no longer mounted
" if $e->IN_UNMOUNT;
	   print "$name is gone
" if $e->IN_IGNORED;
	   print "events for $name have been lost
" if $e->IN_Q_OVERFLOW;

	   # cancel this watcher: remove no further events
	   $e->w->cancel;
	});

	# integration into AnyEvent (works with EV, Glib, Tk, POE...)
	my $inotify_w = AnyEvent->io (
	   fh => $inofity->fileno, poll => 'r', cb => sub { $inotify->poll }
	);

	# manual event loop
	1 while $inotify->poll;

   Streaming Interface
	use Linux::Inotify2 ;

	# create a new object
	my $inotify = new Linux::Inotify2
	   or die "Unable to create new inotify object: $!" ;

	# create watch
	$inotify->watch ("/etc/passwd", IN_ACCESS)
	   or die "watch creation failed" ;

	while () {
	  my @events = $inotify->read;
	  unless (@events > 0) {
	    print "read error: $!";
	    last ;
	  }
	  printf "mask	%d
", $_->mask foreach @events ;
	}

DESCRIPTION

       This module implements an interface to the Linux 2.6.13 and later Inotify file/directory change notification system.

       It has a number of advantages over the Linux::Inotify module:

	  - it is portable (Linux::Inotify only works on x86)
	  - the equivalent of fullname works correctly
	  - it is better documented
	  - it has callback-style interface, which is better suited for
	    integration.

   The Linux::Inotify2 Class
       my $inotify = new Linux::Inotify2
	   Create a new notify object and return it. A notify object is kind of a container that stores watches on file system names and is
	   responsible for handling event data.

	   On error, "undef" is returned and $! will be set accordingly. The following errors are documented:

	    ENFILE   The system limit on the total number of file descriptors has been reached.
	    EMFILE   The user limit on the total number of inotify instances has been reached.
	    ENOMEM   Insufficient kernel memory is available.

	   Example:

	      my $inotify = new Linux::Inotify2
		 or die "Unable to create new inotify object: $!";

       $watch = $inotify->watch ($name, $mask[, $cb])
	   Add a new watcher to the given notifier. The watcher will create events on the pathname $name as given in $mask, which can be any of
	   the following constants (all exported by default) ORed together.

	   "file" refers to any file system object in the watched object (always a directory), that is files, directories, symlinks, device nodes
	   etc., while "object" refers to the object the watcher has been set on itself:

	    IN_ACCESS		 object was accessed
	    IN_MODIFY		 object was modified
	    IN_ATTRIB		 object metadata changed
	    IN_CLOSE_WRITE	 writable fd to file / to object was closed
	    IN_CLOSE_NOWRITE	 readonly fd to file / to object closed
	    IN_OPEN		 object was opened
	    IN_MOVED_FROM	 file was moved from this object (directory)
	    IN_MOVED_TO 	 file was moved to this object (directory)
	    IN_CREATE		 file was created in this object (directory)
	    IN_DELETE		 file was deleted from this object (directory)
	    IN_DELETE_SELF	 object itself was deleted
	    IN_MOVE_SELF	 object itself was moved
	    IN_ALL_EVENTS	 all of the above events

	    IN_ONESHOT		 only send event once
	    IN_ONLYDIR		 only watch the path if it is a directory
	    IN_DONT_FOLLOW	 don't follow a sym link
	    IN_MASK_ADD 	 not supported with the current version of this module

	    IN_CLOSE		 same as IN_CLOSE_WRITE | IN_CLOSE_NOWRITE
	    IN_MOVE		 same as IN_MOVED_FROM | IN_MOVED_TO

	   $cb is a perl code reference that, if given, is called for each event. It receives a "Linux::Inotify2::Event" object.

	   The returned $watch object is of class "Linux::Inotify2::Watch".

	   On error, "undef" is returned and $! will be set accordingly. The following errors are documented:

	    EBADF    The given file descriptor is not valid.
	    EINVAL   The given event mask contains no legal events.
	    ENOMEM   Insufficient kernel memory was available.
	    ENOSPC   The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
	    EACCESS  Read access to the given file is not permitted.

	   Example, show when "/etc/passwd" gets accessed and/or modified once:

	      $inotify->watch ("/etc/passwd", IN_ACCESS | IN_MODIFY, sub {
		 my $e = shift;
		 print "$e->{w}{name} was accessed
" if $e->IN_ACCESS;
		 print "$e->{w}{name} was modified
" if $e->IN_MODIFY;
		 print "$e->{w}{name} is no longer mounted
" if $e->IN_UNMOUNT;
		 print "events for $e->{w}{name} have been lost
" if $e->IN_Q_OVERFLOW;

		 $e->w->cancel;
	      });

       $inotify->fileno
	   Returns the file descriptor for this notify object. When in non-blocking mode, you are responsible for calling the "poll" method when
	   this file descriptor becomes ready for reading.

       $inotify->blocking ($blocking)
	   Clears ($blocking true) or sets ($blocking false) the "O_NONBLOCK" flag on the file descriptor.

       $count = $inotify->poll
	   Reads events from the kernel and handles them. If the notify file descriptor is blocking (the default), then this method waits for at
	   least one event (and thus returns true unless an error occurs). Otherwise it returns immediately when no pending events could be read.

	   Returns the count of events that have been handled.

       @events = $inotify->read
	   Reads events from the kernel. Blocks when the file descriptor is in blocking mode (default) until any event arrives. Returns list of
	   "Linux::Inotify2::Event" objects or empty list if none (non-blocking mode) or error occurred ($! should be checked).

	   Normally you shouldn't use this function, but instead use watcher callbacks and call "->poll".

   The Linux::Inotify2::Event Class
       Objects of this class are handed as first argument to the watcher callback. It has the following members and methods:

       $event->w
       $event->{w}
	   The watcher object for this event.

       $event->name
       $event->{name}
	   The path of the file system object, relative to the watched name.

       $event->fullname
	   Returns the "full" name of the relevant object, i.e. including the "name" member of the watcher (if the watch object is on a directory
	   and a directory entry is affected), or simply the "name" member itself when the object is the watch object itself.

       $event->mask
       $event->{mask}
	   The received event mask. In addition to the events described for "$inotify->watch", the following flags (exported by default) can be
	   set:

	    IN_ISDIR		 event object is a directory
	    IN_Q_OVERFLOW	 event queue overflowed

	    # when any of the following flags are set,
	    # then watchers for this event are automatically canceled
	    IN_UNMOUNT		 filesystem for watched object was unmounted
	    IN_IGNORED		 file was ignored/is gone (no more events are delivered)
	    IN_ONESHOT		 only one event was generated

       $event->IN_xxx
	   Returns a boolean that returns true if the event mask contains any events specified by the mask. All of the "IN_xxx" constants can be
	   used as methods.

       $event->cookie
       $event->{cookie}
	   The event cookie to "synchronize two events". Normally zero, this value is set when two events relating to the same file are generated.
	   As far as I know, this only happens for "IN_MOVED_FROM" and "IN_MOVED_TO" events, to identify the old and new name of a file.

   The Linux::Inotify2::Watch Class
       Watcher objects are created by calling the "watch" method of a notifier.

       It has the following members and methods:

       $watch->name
       $watch->{name}
	   The name as specified in the "watch" call. For the object itself, this is the empty string.	For directory watches, this is the name of
	   the entry without leading path elements.

       $watch->mask
       $watch->{mask}
	   The mask as specified in the "watch" call.

       $watch->cb ([new callback])
       $watch->{cb}
	   The callback as specified in the "watch" call. Can optionally be changed.

       $watch->cancel
	   Cancels/removes this watcher. Future events, even if already queued queued, will not be handled and resources will be freed.

SEE ALSO

       AnyEvent, Linux::Inotify.

AUTHOR

	Marc Lehmann <schmorp@schmorp.de>
	http://home.schmorp.de/

perl v5.14.2							    2011-06-14							     Inotify2(3pm)