How to check if directory contents has changed with PHP?

As already mentioned by others, a better way to solve this would be to trigger a function when particular events happen, that changes the folder. However, if your server is a unix, you can use inotifywait to watch the directory, and then invoke a PHP script.

Here's a simple example:

#!/bin/sh inotifywait --recursive --monitor --quiet --event modify,create,delete,move --format '%f' /path/to/directory/to/watch | while read FILE ; do php /path/to/trigger.php $FILE done 

See also: http://linux.die.net/man/1/inotifywait

What about touching the directory after a user has submitted his image? Changelog says: Requires php 5.3 for windows to work, but I think it should work on all other environments

with inotifywait inside php

$watchedDir = 'watch'; $in = popen("inotifywait --monitor --quiet --format '%e %f' --event create,moved_to '$watchedDir'", 'r'); if ($in === false) throw new Exception ('fail start notify'); while (($line = fgets($in)) !== false) { list($event, $file) = explode(' ', rtrim($line, PHP_EOL), 2); echo "$event $file\n"; } 

IMO edubem's answer is the way to go, however you can do something like this:

if (sha1(serialize(Map('/path/to/directory/', true))) != /* previous stored hash */) { // directory contents has changed } 

Or a more weak / faster version:

if (Size('/path/to/directory/', true) != /* previous stored size */) { // directory contents has changed } 

Here are the functions used:

function Map($path, $recursive = false) { $result = array(); if (is_dir($path) === true) { $path = Path($path); $files = array_diff(scandir($path), array('.', '..')); foreach ($files as $file) { if (is_dir($path . $file) === true) { $result[$file] = ($recursive === true) ? Map($path . $file, $recursive) : $this->Size($path . $file, true); } else if (is_file($path . $file) === true) { $result[$file] = Size($path . $file); } } } else if (is_file($path) === true) { $result[basename($path)] = Size($path); } return $result; } function Size($path, $recursive = true) { $result = 0; if (is_dir($path) === true) { $path = Path($path); $files = array_diff(scandir($path), array('.', '..')); foreach ($files as $file) { if (is_dir($path . $file) === true) { $result += ($recursive === true) ? Size($path . $file, $recursive) : 0; } else if (is_file() === true) { $result += sprintf('%u', filesize($path . $file)); } } } else if (is_file($path) === true) { $result += sprintf('%u', filesize($path)); } return $result; } function Path($path) { if (file_exists($path) === true) { $path = rtrim(str_replace('\\', '/', realpath($path)), '/'); if (is_dir($path) === true) { $path .= '/'; } return $path; } return false; } 

Here's what you may try. Store all pictures in a single directory (or in /username subdirectories inside it to speed things up and to lessen the stress on the FS) and set up Apache (or whaterver you're using) to serve them as static content with "expires-on" set to 100 years in the future. File names should contain some unique prefix or suffix (timestamp, SHA1 hash of file content, etc), so whenever uses changes the file its name gets changed and Apache will serve a new version, which will get cached along the way.

You're thinking the wrong way.

You should execute your directory indexer script as soon as someone's uploaded a new file and it's moved to the target location.

Try deleting the cached version when a user uploads a file to his directory.

When someone tries to view the gallery, look if there's a cached version first. If there's a cached version, load it, otherwise, generate the page, cache it, done.

I was looking for something similar and I just found this:

http://www.franzone.com/2008/06/05/php-script-to-monitor-ftp-directory-changes/

For me looks like a great solution since I'll have a lot of control (I'll be doing an AJAX call to see if anything changed).

Hope that this helps.

Here is a code sample, that would return 0 if the directory was changed. I use it in backups.

The changed status is determined by presence of files and their filesizes. You could easily change this, to compare file contents by replacing

$longString .= filesize($file); 

with

$longString .= crc32(file_get_contents($file)); 

but it will affect execution speed.

#!/usr/bin/php <?php $dirName = $argv[1]; $basePath = '/var/www/vhosts/majestichorseporn.com/web/'; $dataFile = './backup_dir_if_changed.dat'; # startup checks if (!is_writable($dataFile)) die($dataFile . ' is not writable!'); if (!is_dir($basePath . $dirName)) die($basePath . $dirName . ' is not a directory'); $dataFileContent = file_get_contents($dataFile); $data = @unserialize($dataFileContent); if ($data === false) $data = array(); # find all files ang concatenate their sizes to calculate crc32 $files = glob($basePath . $dirName . '/*', GLOB_BRACE); $longString = ''; foreach ($files as $file) { $longString .= filesize($file); } $longStringHash = crc32($longString); # do changed check if (isset ($data[$dirName]) && $data[$dirName] == $longStringHash) die('Directory did not change.'); # save hash do DB $data[$dirName] = $longStringHash; file_put_contents($dataFile, serialize($data)); die('0'); 

very simple. when user uploads or alters something via form submissions then create a small file (i.e. newDetected.txt) in somewhere. then on page load check if file_exists(newDetected.txt) unlink(newDetected.txt) and run recreate function to rebuild dir tree.