[ViewVC] Contents of: cvs/Linux-Inotify2/README

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: $!";
 
     # for Event:
     Event->io (fd =>$inotify->fileno, poll => 'r', cb => sub { $inotify->poll });
     # for Glib:
     add_watch Glib::IO $inotify->fileno, in => sub { $inotify->poll };
     # manually:
     1 while $inotify->poll;

     # add watchers
     $inotify->watch ("/etc/passwd", IN_ACCESS, sub {
        my $e = shift;
        my $name = $e->fullname;
        print "$name was accessed\n" if $e->IN_ACCESS;
        print "$name is no longer mounted\n" if $e->IN_UNMOUNT;
        print "$name is gone\n" if $e->IN_IGNORED;
        print "events for $name have been lost\n" if $e->IN_Q_OVERFLOW;
 
        # cancel this watcher: remove no further events
        $e->w->cancel;
     });

  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\t%d\n", $_->mask foreach @events ; 
     }

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

    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 filesystem names and is
        responsible for handling event data.

        On error, "undef" is returned and $! will be set accordingly. The
        followign 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 filesystem object in the watch'ed object
        (always a directory), that is files, directories, symlinks, device
        nodes etc., while "object" refers to the object the watch 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\n" if $e->IN_ACCESS;
              print "$e->{w}{name} was modified\n" if $e->IN_MODIFY;
              print "$e->{w}{name} is no longer mounted\n" if $e->IN_UNMOUNT;
              print "events for $e->{w}{name} have been lost\n" if $e->IN_Q_OVERFLOW;

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

    $inotify->fileno
        Returns the fileno for this notify object. You are responsible for
        calling the "poll" method when this fileno 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 fileno
        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.

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

  The Linux::Inotify2::Event Class
    Objects of this class are handed as first argument to the watch
    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 filesystem object, relative to the watch name.

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

    $event->mask
    $event->{mask}
        The received event mask. In addition the the events described for
        "$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 watch'ed 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 matches the
        event. 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
    Watch 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 watch. Future events, even if already queued
        queued, will not be handled and resources will be freed.

SEE ALSO
    Linux::Inotify.

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

Revision:	1.7
Committed:	Fri Sep 29 14:41:33 2006 UTC (19 years, 11 months ago) by root
Branch:	MAIN
CVS Tags:	rel-1_1
Changes since 1.6:	+11 -8 lines
Log Message:	* empty log message *
#	Content
1	NAME
2	Linux::Inotify2 - scalable directory/file change notification
3
4	SYNOPSIS
5	Callback interface
6	use Linux::Inotify2;
7
8	# create a new object
9	my $inotify = new Linux::Inotify2
10	or die "Unable to create new inotify object: $!";
11
12	# for Event:
13	Event->io (fd =>$inotify->fileno, poll => 'r', cb => sub { $inotify->poll });
14	# for Glib:
15	add_watch Glib::IO $inotify->fileno, in => sub { $inotify->poll };
16	# manually:
17	1 while $inotify->poll;
18
19	# add watchers
20	$inotify->watch ("/etc/passwd", IN_ACCESS, sub {
21	my $e = shift;
22	my $name = $e->fullname;
23	print "$name was accessed\n" if $e->IN_ACCESS;
24	print "$name is no longer mounted\n" if $e->IN_UNMOUNT;
25	print "$name is gone\n" if $e->IN_IGNORED;
26	print "events for $name have been lost\n" if $e->IN_Q_OVERFLOW;
27
28	# cancel this watcher: remove no further events
29	$e->w->cancel;
30	});
31
32	Streaming Interface
33	use Linux::Inotify2 ;
34
35	# create a new object
36	my $inotify = new Linux::Inotify2
37	or die "Unable to create new inotify object: $!" ;
38
39	# create watch
40	$inotify->watch ("/etc/passwd", IN_ACCESS)
41	or die "watch creation failed" ;
42
43	while () {
44	my @events = $inotify->read;
45	unless (@events > 0) {
46	print "read error: $!";
47	last ;
48	}
49	printf "mask\t%d\n", $_->mask foreach @events ;
50	}
51
52	DESCRIPTION
53	This module implements an interface to the Linux 2.6.13 and later
54	Inotify file/directory change notification sytem.
55
56	It has a number of advantages over the Linux::Inotify module:
57
58	- it is portable (Linux::Inotify only works on x86)
59	- the equivalent of fullname works correctly
60	- it is better documented
61	- it has callback-style interface, which is better suited for
62	integration.
63
64	The Linux::Inotify2 Class
65	my $inotify = new Linux::Inotify2
66	Create a new notify object and return it. A notify object is kind of
67	a container that stores watches on filesystem names and is
68	responsible for handling event data.
69
70	On error, "undef" is returned and $! will be set accordingly. The
71	followign errors are documented:
72
73	ENFILE The system limit on the total number of file descriptors has been reached.
74	EMFILE The user limit on the total number of inotify instances has been reached.
75	ENOMEM Insufficient kernel memory is available.
76
77	Example:
78
79	my $inotify = new Linux::Inotify2
80	or die "Unable to create new inotify object: $!";
81
82	$watch = $inotify->watch ($name, $mask[, $cb])
83	Add a new watcher to the given notifier. The watcher will create
84	events on the pathname $name as given in $mask, which can be any of
85	the following constants (all exported by default) ORed together.
86
87	"file" refers to any filesystem object in the watch'ed object
88	(always a directory), that is files, directories, symlinks, device
89	nodes etc., while "object" refers to the object the watch has been
90	set on itself:
91
92	IN_ACCESS object was accessed
93	IN_MODIFY object was modified
94	IN_ATTRIB object metadata changed
95	IN_CLOSE_WRITE writable fd to file / to object was closed
96	IN_CLOSE_NOWRITE readonly fd to file / to object closed
97	IN_OPEN object was opened
98	IN_MOVED_FROM file was moved from this object (directory)
99	IN_MOVED_TO file was moved to this object (directory)
100	IN_CREATE file was created in this object (directory)
101	IN_DELETE file was deleted from this object (directory)
102	IN_DELETE_SELF object itself was deleted
103	IN_MOVE_SELF object itself was moved
104	IN_ALL_EVENTS all of the above events
105
106	IN_ONESHOT only send event once
107	IN_ONLYDIR only watch the path if it is a directory
108	IN_DONT_FOLLOW don't follow a sym link
109	IN_MASK_ADD not supported with the current version of this module
110
111	IN_CLOSE same as IN_CLOSE_WRITE \| IN_CLOSE_NOWRITE
112	IN_MOVE same as IN_MOVED_FROM \| IN_MOVED_TO
113
114	$cb is a perl code reference that, if given, is called for each
115	event. It receives a "Linux::Inotify2::Event" object.
116
117	The returned $watch object is of class "Linux::Inotify2::Watch".
118
119	On error, "undef" is returned and $! will be set accordingly. The
120	following errors are documented:
121
122	EBADF The given file descriptor is not valid.
123	EINVAL The given event mask contains no legal events.
124	ENOMEM Insufficient kernel memory was available.
125	ENOSPC The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
126	EACCESS Read access to the given file is not permitted.
127
128	Example, show when "/etc/passwd" gets accessed and/or modified once:
129
130	$inotify->watch ("/etc/passwd", IN_ACCESS \| IN_MODIFY, sub {
131	my $e = shift;
132	print "$e->{w}{name} was accessed\n" if $e->IN_ACCESS;
133	print "$e->{w}{name} was modified\n" if $e->IN_MODIFY;
134	print "$e->{w}{name} is no longer mounted\n" if $e->IN_UNMOUNT;
135	print "events for $e->{w}{name} have been lost\n" if $e->IN_Q_OVERFLOW;
136
137	$e->w->cancel;
138	});
139
140	$inotify->fileno
141	Returns the fileno for this notify object. You are responsible for
142	calling the "poll" method when this fileno becomes ready for
143	reading.
144
145	$inotify->blocking ($blocking)
146	Clears ($blocking true) or sets ($blocking false) the "O_NONBLOCK"
147	flag on the file descriptor.
148
149	$count = $inotify->poll
150	Reads events from the kernel and handles them. If the notify fileno
151	is blocking (the default), then this method waits for at least one
152	event (and thus returns true unless an error occurs). Otherwise it
153	returns immediately when no pending events could be read.
154
155	Returns the count of events that have been handled.
156
157	$count = $inotify->read
158	Reads events from the kernel. Blocks in blocking mode (default)
159	until any event arrives. Returns list of "Linux::Inotify2::Event"
160	objects or empty list if none (non-blocking mode) or error occured
161	($! should be checked).
162
163	The Linux::Inotify2::Event Class
164	Objects of this class are handed as first argument to the watch
165	callback. It has the following members and methods:
166
167	$event->w
168	$event->{w}
169	The watcher object for this event.
170
171	$event->name
172	$event->{name}
173	The path of the filesystem object, relative to the watch name.
174
175	$watch->fullname
176	Returns the "full" name of the relevant object, i.e. including the
177	"name" member of the watcher (if the the watch is on a directory and
178	a dir entry is affected), or simply the "name" member itself when
179	the object is the watch object itself.
180
181	$event->mask
182	$event->{mask}
183	The received event mask. In addition the the events described for
184	"$inotify-"watch>, the following flags (exported by default) can be
185	set:
186
187	IN_ISDIR event object is a directory
188	IN_Q_OVERFLOW event queue overflowed
189
190	# when any of the following flags are set,
191	# then watchers for this event are automatically canceled
192	IN_UNMOUNT filesystem for watch'ed object was unmounted
193	IN_IGNORED file was ignored/is gone (no more events are delivered)
194	IN_ONESHOT only one event was generated
195
196	$event->IN_xxx
197	Returns a boolean that returns true if the event mask matches the
198	event. All of the "IN_xxx" constants can be used as methods.
199
200	$event->cookie
201	$event->{cookie}
202	The event cookie to "synchronize two events". Normally zero, this
203	value is set when two events relating to the same file are
204	generated. As far as I know, this only happens for "IN_MOVED_FROM"
205	and "IN_MOVED_TO" events, to identify the old and new name of a
206	file.
207
208	The Linux::Inotify2::Watch Class
209	Watch objects are created by calling the "watch" method of a notifier.
210
211	It has the following members and methods:
212
213	$watch->name
214	$watch->{name}
215	The name as specified in the "watch" call. For the object itself,
216	this is the empty string. For directory watches, this is the name of
217	the entry without leading path elements.
218
219	$watch->mask
220	$watch->{mask}
221	The mask as specified in the "watch" call.
222
223	$watch->cb ([new callback])
224	$watch->{cb}
225	The callback as specified in the "watch" call. Can optionally be
226	changed.
227
228	$watch->cancel
229	Cancels/removes this watch. Future events, even if already queued
230	queued, will not be handled and resources will be freed.
231
232	SEE ALSO
233	Linux::Inotify.
234
235	AUTHOR
236	Marc Lehmann <schmorp@schmorp.de>
237	http://home.schmorp.de/
238