Example for tailing a file (like tail -f) using inotify.
<?php
/**
* Tail a file (UNIX only!)
* Watch a file for changes using inotify and return the changed data
*
* @param string $file - filename of the file to be watched
* @param integer $pos - actual position in the file
* @return string
*/
function tail($file,&$pos) {
// get the size of the file
if(!$pos) $pos = filesize($file);
// Open an inotify instance
$fd = inotify_init();
// Watch $file for changes.
$watch_descriptor = inotify_add_watch($fd, $file, IN_ALL_EVENTS);
// Loop forever (breaks are below)
while (true) {
// Read events (inotify_read is blocking!)
$events = inotify_read($fd);
// Loop though the events which occured
foreach ($events as $event=>$evdetails) {
// React on the event type
switch (true) {
// File was modified
case ($evdetails['mask'] & IN_MODIFY):
// Stop watching $file for changes
inotify_rm_watch($fd, $watch_descriptor);
// Close the inotify instance
fclose($fd);
// open the file
$fp = fopen($file,'r');
if (!$fp) return false;
// seek to the last EOF position
fseek($fp,$pos);
// read until EOF
while (!feof($fp)) {
$buf .= fread($fp,8192);
}
// save the new EOF to $pos
$pos = ftell($fp); // (remember: $pos is called by reference)
// close the file pointer
fclose($fp);
// return the new data and leave the function
return $buf;
// be a nice guy and program good code ;-)
break;
// File was moved or deleted
case ($evdetails['mask'] & IN_MOVE):
case ($evdetails['mask'] & IN_MOVE_SELF):
case ($evdetails['mask'] & IN_DELETE):
case ($evdetails['mask'] & IN_DELETE_SELF):
// Stop watching $file for changes
inotify_rm_watch($fd, $watch_descriptor);
// Close the inotify instance
fclose($fd);
// Return a failure
return false;
break;
}
}
}
}
// Use it like that:
$lastpos = 0;
while (true) {
echo tail($file,$lastpos);
}
?>
inotify_init
(PECL inotify >= 0.1.2)
inotify_init — Initialize an inotify instance
Descrierea
inotify_init
(
) : resource
Initialize an inotify instance for use with inotify_add_watch()
Valorile întoarse
A stream resource or false on error.
Exemple
Example #1 Example usage of inotify
<?php
// Open an inotify instance
$fd = inotify_init();
// Watch __FILE__ for metadata changes (e.g. mtime)
$watch_descriptor = inotify_add_watch($fd, __FILE__, IN_ATTRIB);
// generate an event
touch(__FILE__);
// Read events
$events = inotify_read($fd);
print_r($events);
// The following methods allows to use inotify functions without blocking on inotify_read():
// - Using stream_select() on $fd:
$read = array($fd);
$write = null;
$except = null;
stream_select($read,$write,$except,0);
// - Using stream_set_blocking() on $fd
stream_set_blocking($fd, 0);
inotify_read($fd); // Does no block, and return false if no events are pending
// - Using inotify_queue_len() to check if event queue is not empty
$queue_len = inotify_queue_len($fd); // If > 0, inotify_read() will not block
// Stop watching __FILE__ for metadata changes
inotify_rm_watch($fd, $watch_descriptor);
// Close the inotify instance
// This may have closed all watches if this was not already done
fclose($fd);
?>
Exemplul de mai sus va afișa ceva similar cu:
array(
array(
'wd' => 1, // Equals $watch_descriptor
'mask' => 4, // IN_ATTRIB bit is set
'cookie' => 0, // unique id to connect related events (e.g.
// IN_MOVE_FROM and IN_MOVE_TO events)
'name' => '', // the name of a file (e.g. if we monitored changes
// in a directory)
),
);
A se vedea și
- inotify_add_watch() - Add a watch to an initialized inotify instance
- inotify_rm_watch() - Remove an existing watch from an inotify instance
- inotify_queue_len() - Return a number upper than zero if there are pending events
- inotify_read() - Read events from an inotify instance
- fclose() - Closes an open file pointer
add a note
User Contributed Notes 1 note
david dot schueler at tel-billig dot de ¶
14 years ago
