touch

(PHP 4, PHP 5, PHP 7, PHP 8)

touch — Establece el momento de acceso y modificación de un archivo

Descripción

touch(string $filename, int $time = time(), int $atime = ?): bool

Intenta establecer los momentos de acceso y modificación del archivo nombrado por el parámetro filename al valor dado en time. Observe que el momento de acceso se modifica siempre, sin importar el número de parámetros.

Si el archivo no existe, será creado.

Parámetros

filename: El nombre del archivo que va a ser afectado.
time: El momento de afectación. Si time no es proporcionado, se usa la hora actual del sistema.
atime: Si está presente, el momento de acceso del nombre de archivo dado se establece al valor de atime. De otro modo, se establece al valor pasado al parámetro time. Si ninguno está presente, se usa el momento actual del sistema.

Valores devueltos

Devuelve true en caso de éxito o false en caso de error.

Historial de cambios

Versión	Descripción
5.3.0	Se hizo posible cambiar el momento de modificación de un directorio bajo Windows.

Ejemplos

Ejemplo #1 Ejemplo de touch()

<?php
if (touch($nombre_archivo)) {
    echo 'El momento de modificación de ' . $nombre_archivo . ' ha sido cambiada a la hora actual';
} else {
    echo 'Lo siento, no se pudo cambiar el momento de modificación de ' . $nombre_archivo;
}
?>

Ejemplo #2 touch() usando el parámetro time

<?php
// Este es el momento afectado, lo estableceremos a una hora antes
$momento = time() - 3600;

// Afectar el archivo
if(!touch('archivo.txt', $momento)) {
    echo 'Lo sieno, algo fue mal...';
} else {
    echo 'Archivo afectado con éxito';
}
?>

Notas

Nota:
Observe que el tiempo de resolución quizá varia según el sistema de ficheros.

Advertencia

Antes de PHP 5.3.0 no era posible cambiar el momento de modificación de un directorio con esta función bajo Windows.

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User Contributed Notes 18 notes

down

anon ¶

10 years ago


Note that when PHP is called by f.e. apache or nginx instead of directly from the command line, touch() will not prefix the location of the invoking script, so the supplied filename must contain an absolute path.

With script started from /home/user/www, this will not touch "/home/user/www/somefile":

<?php
    touch( 'somefile' );
?>

But this will:

<?php
    touch( __DIR__ . '/somefile' );
?>

down

Charles Belov ¶

18 years ago


Update the access time without updating the modified time:

Unix command: touch -a filename

PHP: touch(filename, date('U', filemtime(filename)), time())

down

Jeff ¶

16 years ago


I've been trying to set a filemtime into the future with touch() on PHP5.

It seems touch $time has a future limit around 1000000 seconds (11 days or so). Beyond this point it reverts to a previous $time.

It doesn't make much sense but I could save you hours of time.

$time = time()+1500000;
touch($cachedfile,$time);

down

mrgrier at yahoo dot com ¶

15 years ago


At least on Linux, touch will not change the time on a symlink itself, but on the file/directory it points to. The only way to work around this is to unlink the symlink, then recreate it.

It took a bit of searching to discover this. The OS itself provides no way to do it. Many people wondered why anyone would want to do this. I use symlinks inside a web tree to point to files outside the web tree. After a certain length of time has passed, I want the symlinks to die, so the files cannot be successfully hotlinked.

down

ernst at cron-it dot de ¶

15 years ago


To touch a file without being owner, it is much easier:



<?php

function touchFile($file) {

  fclose(fopen($file, 'a'));

}

?>

down

bosslog at gmail dot com ¶

14 years ago


I has passed a small test to check which function is faster to create a new file. 

file_put_contents vs touch

<?php
for($i = 0; $i < 100; $i++)
{
     file_put_contents('dir/file'.$i, '');
}
?>
Average time: 0,1145s

<?php
for($i = 0; $i < 100; $i++)
{
     touch('dir/file'.$i);
}
?>
Average time: 0,2322s

So, file_put_contents is faster than touch, about two times.

down

chris dot dallaire at csquaredsystems dot com ¶

14 years ago


I needed to use this to touch the /etc/cron.d directory when I updated some files in there. I know the docs say this isn't necessary, but I'm finding that i need to do it in order form my changes to be picked up quickly. 

I ran into the permissions error as well and I found that using chmod 777 /etc/cron.d does the trick.

So, you should be able to use the PHP touch function on a directory that has open write access.

Of course, this isn't the most secure approach, but in our application it's not a big deal for that folder to not be super secure.

down

ddalex at gmail dot com ¶

16 years ago


Actually, Glen is right, PHP won't touch if it is not the current owner of the file, even if the directory and files are writeable by the PHP user.

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spam at webmastersguide dot com ¶

19 years ago


If you're going to go around deleting (unlinking) files
that you don't own just in order to change the modification
time on the file, you darn well better chown() the file 
back to it's original ownership after you are done and
chmod() it back to it's correct permissions.  Otherwise 
you will almost certainly break things.  Additionally the
code listed for touch()ing a file you don't own should 
set the file creation time back to it's original time if 
what is wanted is to just change the modification time.
Also, the code listed will break things if there is an i/o 
error such as disk full or too many files in the directory.
Here's how the code SHOULD be written:

Create the new file FIRST, rather than last, with a different
name such as $file.tmp.
Read the ownership, permissions, and creation time of the old file.
Set permissions and creation time of the new file the same as the old.
Rename the new file to the name of the old.
chown() the new file to the user that owned the file it's replacing.

Please be careful adding to the documentation if you've 
never taken programming 101.

down

info at archiwumrocka dot art dot pl ¶

15 years ago


Only way to change modification date in catalogue is to create file in via touch() and dalete it with unlink():



<?php

$dir    = 'temp';

$files1 = scandir($dir);



$files1 = array_slice($files1, 2);



foreach ($files1 as $key => $val) 

{

    if (!is_dir($val)) continue;

    if (!touch($val)) 

    {

        touch($val . "/plik.txt");

        unlink($val . "/plik.txt");

    }

}

?>

down

rf_public at yahoo dot co dot uk ¶

19 years ago


Note: the script to touch a file you don't own will change it's owner so ensure permissions are correct or you could lose access to it

down

feathern at yahoo dot com ¶

22 years ago


Neat little script that will give you a list of all modified files in a certain folder after a certain date:

$filelist = Array();
$filelist = list_dir("d:\\my_folder");
for($i=0;$i<count($filelist);$i++){
    $test = Array();
    $test = explode("/",date("m/d/Y",filemtime($filelist[$i])));
//example of files that are later then
//06/17/2002
    if(($test[2] > 2001) && ($test[1] > 16) && ($test[0] > 5)){
        echo $filelist[$i]."\r\n";
    }
    clearstatcache();
}
function list_dir($dn){
    if($dn[strlen($dn)-1] != '\\') $dn.='\\';
    static $ra = array();
    $handle = opendir($dn);
    while($fn = readdir($handle)){
        if($fn == '.' || $fn == '..') continue;
        if(is_dir($dn.$fn)) list_dir($dn.$fn.'\\');
        else $ra[] = $dn.$fn;
    }
    closedir($handle);
    return $ra;
}

down

picek dot jaroslav at protonmail dot com ¶

8 months ago


I have found out that setting a negative *mtime* deletes the file. The following code always deletes the file at $path while $touch returns true.

<?php
$path = '/folder/file';
$timestamp = -1;

$touch = touch($path, $timestamp);
?>

Running PHP 7.4.5

down

guy at forster design dot com ¶

19 years ago


Here's a little workaround that allows the PHP user to touch a file it doesn't own:

<?php

    $target_file = "/path/to/file/filename.txt"; //system filepath to your file
    $file_content = implode("",file($target_file));
    @unlink($target_file);
    if($savetofile = fopen($target_file, "w")) {
        fputs($savetofile, $file_content);
        fclose($savetofile);
    }
    $new_date = strtotime("23 April 2005"); // set the required date timestamp here
    touch($target_file,$new_date);
 
?>

Of course, PHP needs to have write access to the folder containing the file you want to touch, but that should be easy to arrange.

down

-1

centurianii at yahoo dot co dot uk ¶

7 years ago


A better explanation:

For file $file and UNIX time stored in vars $access and $modified

- change only access time
\touch($file, \filemtime($file), $access);

- change only modified time
\touch($file, $modified, \fileatime($file));

- change both access and modified time
\touch($file, $modified, $access);

Seeing the results:

//use a session cookie stored in a custom folder
$file = '/var/www/test_com/session/sess_qfn587cudfpgsijm1bs4d81s75';
echo 'stats for sess_qfn587cudfpgsijm1bs4d81s75<br/>';
\clearstatcache();
echo 'access: '.\date("Y-m-d H:i:s", \fileatime($file)).'<br/>';
echo 'modified: '.\date("Y-m-d H:i:s", \filemtime($file)).'<br/>';
echo 'change access to now, modified +1 hour<br/>';
\touch($x, \filemtime($file)+3600, time());
\clearstatcache();
echo 'access: '.\date("Y-m-d H:i:s", \fileatime($file)).'<br/>';
echo 'modified: '.\date("Y-m-d H:i:s", \filemtime($file)).'<br/>';

Notice the double call to clearstatcache()!

down

-2

Glen ¶

17 years ago


In unix on the command-line, you can touch files you don't own - but like other comments on this page state - PHP's built in touch won't work.

I simple alternative (on unix):

<?php

    function touch_it_good($filename)
    {
        exec("touch {$filename}");
    }
?>

down

-3

Radon8472 ¶

16 years ago


Important info:

touch() used on a directory always returns FALSE and prints "Permission denied" on NTFS and FAT Filesystem (tested on winXP).

down

-4

csouth at xistins dot com ¶

9 years ago


An earlier comment referenced a code snippet that showed file_put_contents() was faster the touch for creating files. I re-ran the same tests on PHP 5.5.9 and this seems to no longer be the case.

<?php
$startTime = microtime(true);
for($i = 0; $i < 100000; $i++)
{
    file_put_contents('dir/file'.$i, '');
    unlink('dir/file'.$i);
}
echo "Time: ".(microtime(true)-$startTime)."\n"; // Time: 2.6902809143066

$startTime = microtime(true);
for($i = 0; $i < 100000; $i++)
{
    touch('dir/file'.$i);
    unlink('dir/file'.$i);
}
echo "Time: ".(microtime(true)-$startTime)."\n"; // Time: 2.3343770503998
?>

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