inotify_read

<?php

$wd_constants = array(
1 => array('IN_ACCESS','File was accessed (read)'),
2 => array('IN_MODIFY','File was modified'),
4 => array('IN_ATTRIB','Metadata changed (e.g. permissions, mtime, etc.)'),
8 => array('IN_CLOSE_WRITE','File opened for writing was closed'),
16 => array('IN_CLOSE_NOWRITE','File not opened for writing was closed'),
32 => array('IN_OPEN','File was opened'),
128 => array('IN_MOVED_TO','File moved into watched directory'),
64 => array('IN_MOVED_FROM','File moved out of watched directory'),
256 => array('IN_CREATE','File or directory created in watched directory'),
512 => array('IN_DELETE','File or directory deleted in watched directory'),
1024 => array('IN_DELETE_SELF','Watched file or directory was deleted'),
2048 => array('IN_MOVE_SELF','Watch file or directory was moved'),
24 => array('IN_CLOSE','Equals to IN_CLOSE_WRITE | IN_CLOSE_NOWRITE'),
192 => array('IN_MOVE','Equals to IN_MOVED_FROM | IN_MOVED_TO'),
4095 => array('IN_ALL_EVENTS','Bitmask of all the above constants'),
8192 => array('IN_UNMOUNT','File system containing watched object was unmounted'),
16384 => array('IN_Q_OVERFLOW','Event queue overflowed (wd is -1 for this event)'),
32768 => array('IN_IGNORED','Watch was removed (explicitly by inotify_rm_watch() or because file was removed or filesystem unmounted'),
1073741824 => array('IN_ISDIR','Subject of this event is a directory'),
1073741840 => array('IN_CLOSE_NOWRITE','High-bit: File not opened for writing was closed'),
1073741856 => array('IN_OPEN','High-bit: File was opened'),
1073742080 => array('IN_CREATE','High-bit: File or directory created in watched directory'),
1073742336 => array('IN_DELETE','High-bit: File or directory deleted in watched directory'),
16777216 => array('IN_ONLYDIR','Only watch pathname if it is a directory (Since Linux 2.6.15)'),
33554432 => array('IN_DONT_FOLLOW','Do not dereference pathname if it is a symlink (Since Linux 2.6.15)'),
536870912 => array('IN_MASK_ADD','Add events to watch mask for this pathname if it already exists (instead of replacing mask).'),
2147483648 => array('IN_ONESHOT','Monitor pathname for one event, then remove from watch list.')
);

$path = $argv[1];

$fd = inotify_init();
stream_set_blocking($fd, 0);
$watch_descriptor = inotify_add_watch($fd, $path, IN_ALL_EVENTS);

$poll = 0;
while (true) {
  $ecount = 0;
  $fcount = 0;
  // Poll for queued events, generated meanwhile
  // Because while (true) { } has some seriously bad mojo
  sleep(5);
  $poll++;
  $events = inotify_read($fd);
  if ($events) $ecount = count($events);
  echo "=== ".date("Y-m-d H:i:s")." inotify poll #$poll contains ".$ecount." events";
  if ($events) echo ":";
  echo "\n";
  if ($events) {
        foreach ($events as $event) {
                $fcount++;
                echo "        inotify Event #".$fcount." - Object: ".$event['name'].": ".$wd_constants[$event['mask']][0]." (".$wd_constants[$event['mask']][1].")\n";
        }
  }
}

inotify_rm_watch($fd, $watch_descriptor);

fclose($fd);

?>

once the watch is read, it is removed from the queue.
(inotify_queue_len will return 0)