Get the last modified date of a remote file

Question

I would like to get the last modified date of a remote file by means of curl. Does anyone know how to do that?

Answer 1

You could probably do something like this using curl_getinfo():

<?php
$curl = curl_init('http://www.example.com/filename.txt');

//don't fetch the actual page, you only want headers
curl_setopt($curl, CURLOPT_NOBODY, true);

//stop it from outputting stuff to stdout
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);

// attempt to retrieve the modification date
curl_setopt($curl, CURLOPT_FILETIME, true);

$result = curl_exec($curl);

if ($result === false) {
    die (curl_error($curl)); 
}

$timestamp = curl_getinfo($curl, CURLINFO_FILETIME);
if ($timestamp != -1) { //otherwise unknown
    echo date("Y-m-d H:i:s", $timestamp); //etc
} 

Answer 2

In PHP you can use the native function get_headers():

<?php
$h = get_headers($url, 1);

$dt = NULL;
if (!($h || strstr($h[0], '200') === FALSE)) {
    $dt = new \DateTime($h['Last-Modified']);//php 5.3
}

Answer 3

From php's article:

<?php
// outputs e.g.  somefile.txt was last modified: December 29 2002 22:16:23.

$filename = 'somefile.txt';
if (file_exists($filename)) {
    echo "$filename was last modified: " . date ("F d Y H:i:s.", filemtime($filename));
}
?>

filemtime() is the key here. But I'm not sure if you can get the last modified date of a remote file, since the server should send it to you... Maybe in the HTTP headers?