>PHP: chmod - Manual

DescripciÃ³n

int chmod ( string nombre_archivo, int modo )

Trata de cambiar los permisos del archivo especificado por nombre_archivo a los permisos dados por modo.

Note que modo no es asumido de forma automÃ¡tica como un valor octal. Para asegurar que se hace la operaciÃ³n esperada necesitas anteponer un cero (0) como prefijo del parÃ¡metro modo:


<?php

chmod("/somedir/somefile", 755);   // decimal; probablemente incorrecto   

chmod("/somedir/somefile", "u+rwx,go+rx"); // string; incorrecto

chmod("/somedir/somefile", 0755);  // octal; valor correcto 

?>

El parÃ¡metro modo consiste de tres componentes de valor octal que especifican las restricciones de acceso para el propietario, el grupo de usuarios al que pertenece el propietario del archivo, y todo el mundo, e ese orden. Uno de los componentes puede ser calculado al agregarle los permisos necesarios para ese usuario en especifico, El nÃºmero 1 significa que tiene permisos de ejecuciÃ³n, el nÃºmero 2 significa que puede modificar el contenido del archivo, el nÃºmero 4 significa que puede leer el contenido del archivo. Agrege estos valores para especificar los permisos necesrios. TambiÃ©n se puede leer mÃ¡s acerca de los modos en sistemas Unix con los comandos 'man 1 chmod' y 'man 2 chmod'.


<?php

// Lectura y escritura para el propietario, y nada para los demas

chmod("/somedir/somefile", 0600);



// Lectura y escritura para el propietario, y lectura para los demas

chmod("/somedir/somefile", 0644);



// todos los permisos par el propietario, lectyra y escritura para los demas 

chmod("/somedir/somefile", 0755);



// Todo para el propietario, lectura y ejecucion para el grupo del propietario

chmod("/somedir/somefile", 0750);

?>

Devuelve TRUE si todo se llevÃ³ a cabo correctamente, FALSE en caso de fallo.

Nota: El usuario actual es con el cual PHP se ejecuta. Es probable que no sea el mismo usuario que usa para accesos FTP o por shell.

Nota: Esta funcion no funcionara con ficheros remotos ya que el fichero a examinar tiene que estar disponible desde el sistema de ficheros del servidor.

Nota: Cuando safe mode estÃ¡ activado, PHP checa si los archivos o directorios con lo que quiere trabajar tienen la misma identificaciÃ³n de usuario (UID) (propietario) que el que estÃ¡ ejecutando el script. AdemÃ¡s no puede cambiar el SUID, SGID y los sticky bits.

Ver tambiÃ©n chown() y chgrp().

add a note User Contributed Notes
chmod

Chris (AT) deVidal (DOT) tv
23-Aug-2006 09:44


As noted in a previous post, to use a four-digit chmod (e.g. 1777), you must add a zero to the beginning (01777).



I also discovered this with sgid on directories (02770).



By the way, sgid on dirs is a fantastic way to ensure the group "sticks" on all newly create files and directories created inside that one.  That way all members of a particular group can edit files without using 777 permissions.



To use sgid on directories, use 02XXX (where XXX is the normal permissions e.g. 770 (best security) or 775 (OK) or 777 (terrible security) or 771 (world users can traverse the directory to get to a subdirectory where they have rights)).



TenThousandDollarOffer.com

NeoSmart Technologies
25-Jul-2006 03:08


The program mentioned below (CHMOD-Win) has been rewritten since, and CHMOD-Win version 3.0 is available for download at http://neosmart.net/dl.php?id=4



It is a conversion utility for CHMOD on Windows and ACL on Linux, comes in handy for installing commercial scripts or defining security policies.

neil at 11 out of 10
11-Apr-2006 12:20


If you get a warning like chmod(): Operation not permitted in /home/folder/public_html/admin/includefiles/fileupload.php on line 24



You can use the ftp_site() function to send a CHMOD command through.

<?php



$ftp_details['ftp_user_name'] = $row['username'];

$ftp_details['ftp_user_pass'] = $row['password'];

$ftp_details['ftp_root'] = '/public_html/';

$ftp_details['ftp_server'] = 'ftp'.$_SERVER['HTTP_HOST'];



function chmod_11oo10($path, $mod, $ftp_details)

{

    // extract ftp details (array keys as variable names)

    extract ($ftp_details);

    

    // set up basic connection

    $conn_id = ftp_connect($ftp_server);

    

    // login with username and password

    $login_result = ftp_login($conn_id, $ftp_user_name, $ftp_user_pass);

    

    // try to chmod $path directory

    if (ftp_site($conn_id, 'CHMOD '.$mod.' '.$ftp_root.$path) !== false) {

        $success=TRUE;

    } 

    else {

        $success=FALSE;

    }



    // close the connection

    ftp_close($conn_id);

    return $success;

}

?>

The key thing to remember is that the document root and the ftp root are not the same.

e.g. document root may be "/home/folder/public_html/"

but the ftp root might be "/public_html/"



Hope this helps someone.  You might need this solution if you are on a shared server.

memp
22-Aug-2005 03:04


If you are storing your mode in a variable like



$mode = 0755;



you will run into the inevitable octal mode problem.  An easy way around that is to use the octdec() function.



chmod("some_filename.ext", octdec($mode));

masha at mail dot ru
10-Jul-2005 09:23


Usefull reference:



Value    Permission Level

400    Owner Read

200    Owner Write

100    Owner Execute

40    Group Read

20    Group Write

10    Group Execute

4    Global Read

2    Global Write

1    Global Execute



(taken from http://www.onlamp.com/pub/a/php/2003/02/06/php_foundations.html)

alex at feidesign dot com
01-Apr-2005 04:20


If you cannot chmod files/directories with PHP because of safe_mode restrictions, but you can use FTP to chmod them, simply use PHP's FTP-functions (eg. ftp_chmod or ftp_site) instead. Not as efficient, but works.

info at rvgate dot nl
02-Feb-2005 05:12


When using ftp_rawlist, in order to get the chmod number from the attributes, i use this code:



<?php

function chmodnum($mode) {

    $realmode = "";

    $legal =  array("","w","r","x","-");

    $attarray = preg_split("//",$mode);

    for($i=0;$i<count($attarray);$i++){

        if($key = array_search($attarray[$i],$legal)){

            $realmode .= $legal[$key];

        }

    }

    $mode = str_pad($realmode,9,'-');

    $trans = array('-'=>'0','r'=>'4','w'=>'2','x'=>'1');

    $mode = strtr($mode,$trans);

    $newmode = '';

    $newmode .= $mode[0]+$mode[1]+$mode[2];

    $newmode .= $mode[3]+$mode[4]+$mode[5];

    $newmode .= $mode[6]+$mode[7]+$mode[8];

    return $newmode;

}

?>

some examples:



drwxr-xr-x => 755

drwxr-xr-x => 755

dr-xr-xr-x => 555

drwxr-xr-x => 755

drwxr-xr-x => 755

drwxr-xr-x => 755

drwxr-xr-x => 755

drwxrwxrwt => 776

drwxr-xr-x => 755

drwxr-xr-x => 755

lrwxrwxrwx => 777



used some of already posted code...

haasje at welmers dot net
27-Nov-2004 12:09


For recursive chmod'ing see the function below.

Only really usefull when chmod'ing a tree containing directories only, jet, since you don't want an executable bit on a regular file. Who completes the function so it's accepting strings like "g+w", and it's as usefull as unix "chmod -R" ? ;-)



<?php



function chmod_R($path, $filemode) { 

    if (!is_dir($path))

       return chmod($path, $filemode);



    $dh = opendir($path);

    while ($file = readdir($dh)) {

        if($file != '.' && $file != '..') {

            $fullpath = $path.'/'.$file;

            if(!is_dir($fullpath)) {

              if (!chmod($fullpath, $filemode))

                 return FALSE;

            } else {

              if (!chmod_R($fullpath, $filemode))

                 return FALSE;

            }

        }

    }

 

    closedir($dh);

    

    if(chmod($path, $filemode))

      return TRUE;

    else 

      return FALSE;

} 

?>

PerfectWeb
22-Nov-2004 07:58


As noted by others below... 1) you cannot pass a string to chmod() as the mode, and 2) decimals work as well as octals for the mode.



If you need to come up with the mode on the fly (maybe based on user input) and want to use something like:



$mode = '0'.$owner.$group.$public;



you can use your $mode (which is a string) with chmod like this:



<?php

 // octal mode in a string i.e. '0755'

 $mode = '0'.$owner.$group.$public;



 $mode_dec = octdec($mode);    // convert octal mode to decimal

 chmod($filename, $mode_dec);

?>

fernando at gym-group dot com
12-Nov-2004 07:10


about chmod,

Problably you have a local server to simulate your scripts before upload them to the server. No matter if you use Apache under windows or IIS ,  a chmod instruction like chmod($filename,O777) may not work because windows does not handle that kind of permission's format.

So being in your local server, if you have a only read file and you try to erase, it will show that you dont have permissions even when you have already executed your chmod instrucction correctly. Just up the script it must work well in your internet server if it is a linux machine



sobre chmod,

Probablemente usas un servidor local para probar tus scripts antes de subirlos al servidor en internet. No importa si usas Apache bajo windows o IIS, una instruccion como chmod(nombre_archivo,O777) podrá no trabajar por que windows no maneja esa estructura para definir los permisos.

Estando en tu servidor local, si tienes un archivo de solo lectura y tratas de borrarlo,  se mostrará un error diciendo que no tienes permisos aún despúes de haber ejecutado chmod correctamente. Sube tu script, si tu servidor es una máquina linux, el script trabajará sin problemas en internet.



Fernando Yepes C.

Oliver Hankeln
01-Jul-2004 08:21


Well, you don't need octals.

You need a value that can easily computed and remembered if printed in octal. 

511 (decimal) is the same as 777 (octal).

So it's the same wether you write

chmod("foo",511)

or 

chmod("foo",0777)



The latter is just better readable.

raven_25041980 at yahoo dot com
24-May-2004 10:45


If you have a mode as a string, chmod will insanely mess up your permissions. Instead of using 



<?php 



@chmod($file_or_dir_name, $mode);



?>



use 



<?php 



@chmod(file_or_dir_name, intval($mode, 8));



?>



where 8 -> the base to convert into. You need octals, baby, for chmod...



More on intval here: http://www.php.net/manual/en/function.intval.php

agrenier at assertex dot com
02-Apr-2004 05:17


If you find that chmod does not work on your file and that a new file cannot be created, first try to chmod the directory where the file is being created to 0666/0777. Then PHP should be able to write/append files with mode 0644.

agrenier at assertex dot com
02-Apr-2004 05:11


This function will chmod a $filename before writing to it if:



1 - It exists

2 - It is not writeable

3 - PHP has permission to chmod files



If PHP can't chmod, then the script will end. Otherwise it will attempt to write to a new file.



<?php



    function file_write($filename, $flag, &$content) { 

        if (file_exists($filename)) {

            if (!is_writable($filename)) {

                if (!chmod($filename, 0666)) {

                     echo "Cannot change the mode of file ($filename)";

                     exit;

                };

            }

        }

        if (!$fp = @fopen($filename, $flag)) {

            echo "Cannot open file ($filename)";

            exit;

        }

        if (fwrite($fp, $content) === FALSE) {

            echo "Cannot write to file ($filename)";

            exit;

        } 

        if (!fclose($fp)) {

            echo "Cannot close file ($filename)";

            exit;

        }

    }



?>

Jazeps Basko
27-Jan-2004 07:37


To convert 'rwxr-xr--' to a number representation of chmod, i use this:

<?php

    function chmodnum($mode) {

        $mode = str_pad($mode,9,'-');

        $trans = array('-'=>'0','r'=>'4','w'=>'2','x'=>'1');

        $mode = strtr($mode,$trans);

        $newmode = '';

        $newmode .= $mode[0]+$mode[1]+$mode[2];

        $newmode .= $mode[3]+$mode[4]+$mode[5];

        $newmode .= $mode[6]+$mode[7]+$mode[8];

        return $newmode;

    }

?>

pmichaud at pobox dot com
19-Apr-2003 03:45


In the previous post, stickybit avenger writes:


    Just a little hint. I was once adwised to set the 'sticky bit', i.e. use 1777 as chmod-value...





Note that in order to set the sticky bit on a file one must use '01777' (oct) and not '1777' (dec) as the parameter to chmod:





<?php


    chmod("file",01777);   // correct


     chmod("file",1777);    // incorrect, same as chmod("file",01023), causing no owner permissions!


?>





Rule of thumb: always prefix octal mode values with a zero.

sticky bit avenger
12-Mar-2003 03:30


Just a little hint. I was once adwised to set the 'sticky bit', i.e. use 1777 as chmod-value. Do NOT do this if you don't have root privileges. When 'sticky bit' is set ONLY the fileuser can delete it afterwards, typically 'httpd' or something like that in case of an upload-script for example. I was unaware of this and actually had to make a script for deleting these files as I could not do this from ftp/ssh even though I did have read/write/execute access to both files and folders. Use simply '0777' or similiar.

Half-Dead at nospam dot com
08-Nov-2002 02:42


[Editor's note:


That is due the fact Win32 systems treat premissions. You do not really have any other levels but read-only.





Maxim]








On WinME with apache chmod also works to a certain limit.





What happens is that apparently only the first number is counted, so 0666 (read-write) is the same as 0777, 0644, 0600, etc, and 0444 (read-only) is the same as 477, 400, etc.





..didn't test 0500 series

FF7Cayn at gmx dot de
27-Oct-2001 05:09


It does work on Windows.


I use Win 98 with the Sambar Server.


The only chmods allowed are the 775 and 666 mod. 775 for non-writeable and 666 for writeable. The only thing is that the usergroups doesn't work.


Note: the 0 at the start doesn't work with windows. use only the decimal kind.


Have fun :)

jon at zend dot com
15-Oct-2001 08:37


if 'mode' is held in a variable and is and octal value you need to convert it to decimal before passing it to the function:


chmod ($filename, octdec($mode))

gnettles2 at home dot com
24-Aug-2001 11:20


Usually when you're trying to write to af file, you'll need to chmod the file to something like 666 or 755. You can use a command to chmod the file for you, which is especially useful when you're making a script where you're setting it up so that your users don't have to peform a bunch of actions to setup the script. When i wrote my news program script, I only had two files. install.php and config.php. All you had to do was chmod install.php to 666 and open it up in a web browser and answer a few questions. The script itself setup the rest of the files and chmodded them for you.

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MANUAL DE PHP

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chmod

DescripciÃ³n