(PHP 4, PHP 5, PHP 7, PHP 8)
is_link — Tells whether the filename is a symbolic link
filenamePath to the file.
Upon failure, an E_WARNING is emitted.
Example #1 Create and confirm if a file is a symbolic link
<?php
$link = 'uploads';
if (is_link($link)) {
echo readlink($link);
} else {
symlink('uploads.php', $link);
}
?>Note: The results of this function are cached. See clearstatcache() for more details.
As of PHP 5.0.0, this function can also be used with some URL wrappers. Refer to Supported Protocols and Wrappers to determine which wrappers support stat() family of functionality.
To find out whether a file is hardlinked to another filename, check the number of links of the stat() output. If it is >1 there is another filename for that file.
To find out whether two filenames are pointing to the same file, check the inode number of those 2 filenames. If it is equal, the 2 filenames are hardlinked together.A workaround for Windows LNK files:
<?php
function _is_link($filename)
{
if(is_link($filename))
return true;
$ext = substr(strrchr($filename, '.'), 1);
if(strtolower($ext) == 'lnk')
{
return (_readlink($filename) ? true : false);
}
return false;
}
function _readlink($file)
{
if(file_exists($file))
{
if(is_link($file))
{
return readlink($file);
}
// Get file content
$handle = fopen($file, "rb");
$buffer = array();
while(!feof($handle))
{
$buffer[] = fread($handle, 1);
}
fclose($handle);
// Test magic value and GUID
if(count($buffer) < 20)
return false;
if($buffer[0] != 'L')
return false;
if((ord($buffer[4]) != 0x01) ||
(ord($buffer[5]) != 0x14) ||
(ord($buffer[6]) != 0x02) ||
(ord($buffer[7]) != 0x00) ||
(ord($buffer[8]) != 0x00) ||
(ord($buffer[9]) != 0x00) ||
(ord($buffer[10]) != 0x00) ||
(ord($buffer[11]) != 0x00) ||
(ord($buffer[12]) != 0xC0) ||
(ord($buffer[13]) != 0x00) ||
(ord($buffer[14]) != 0x00) ||
(ord($buffer[15]) != 0x00) ||
(ord($buffer[16]) != 0x00) ||
(ord($buffer[17]) != 0x00) ||
(ord($buffer[18]) != 0x00) ||
(ord($buffer[19]) != 0x46))
{
return false;
}
$i = 20;
if(count($buffer) < ($i + 4))
return false;
$flags = ord($buffer[$i]);
$flags = $flags | (ord($buffer[++$i]) << 8);
$flags = $flags | (ord($buffer[++$i]) << 16);
$flags = $flags | (ord($buffer[++$i]) << 24);
$hasShellItemIdList = ($flags & 0x00000001) ? true : false;
$pointsToFileOrDir = ($flags & 0x00000002) ? true : false;
if(!$pointsToFileOrDir)
return false;
if($hasShellItemIdList)
{
$i = 76;
if(count($buffer) < ($i + 2))
return false;
$a = ord($buffer[$i]);
$a = $a | (ord($buffer[++$i]) << 8);
}
$i = 78 + 4 + $a;
if(count($buffer) < ($i + 4))
return false;
$b = ord($buffer[$i]);
$b = $b | (ord($buffer[++$i]) << 8);
$b = $b | (ord($buffer[++$i]) << 16);
$b = $b | (ord($buffer[++$i]) << 24);
$i = 78 + $a + $b;
if(count($buffer) < ($i + 4))
return false;
$c = ord($buffer[$i]);
$c = $c | (ord($buffer[++$i]) << 8);
$c = $c | (ord($buffer[++$i]) << 16);
$c = $c | (ord($buffer[++$i]) << 24);
$i = 78 + $a + $b + $c;
if(count($buffer) < ($i +1))
return false;
$linkedTarget = "";
for(;$i < count($buffer); ++$i)
{
if(!ord($buffer[$i]))
break;
$linkedTarget .= $buffer[$i];
}
if(empty($linkedTarget))
return false;
return $linkedTarget;
}
return false;
}
if(_is_link('test.lnk'))
{
echo _readlink('test.lnk');
}
?>Careful when using is_link() in thread-safe builds with the self-referential directory entry ".". On ZTS builds is_link("/home/symlink/.") will return true whereas it returns false on non-ZTS builds.On windows, take care that is_link returns false for Junctions.
Ways of telling apart a directory from a junction include doing both a stat() and and lstat() call and checking if there is any difference in the resultsFor me (Debian Sarge VPS) is_link returns true even for directories if you don't add a trailing slash to the filename.
<?php
if ($dir{strlen($dir)-1} == '/') $dir = substr($dir, 0, -1);
is_link($dir);
?>
This works for me. It can't detect a symlink somewhere in a complete path, though (i.e. is_link(/www/somedir/file.php) will return false, just as is_link(/www/) would)@radon8472 at hotmail dot com
The windows .lnk-things are real files, the explorer only treats them like links. Try to open one with Win+R->"notepad X:\Path\Visiblefilename.lnk You will see much 0-Bytes, but the linked path is displayed right on the screen. It should be possible to do the same by php.On my SuSE 7.2 is_link does not work on directories, but to find out, if a dir is a link, I use now this:
$linkdir = $path.$linkdirname;
if (realpath($linkdir) != realpath($path)."/".$linkdirname):
//$linkdir is a symbolic linked dir!
...
and this works fine :-)
Andreas DickOn Mac OSX, to see if a file is a FInder alias:
<?PHP
if( getFinderAlias( $someFile , $target ) ) {
echo $target;
}
else {
echo "File is not an alias";
}
function getFinderAlias( $filename , &$target ) {
$getAliasTarget = <<< HEREDOC
-- BEGIN APPLESCRIPT --
set checkFileStr to "{$filename}"
set checkFile to checkFileStr as POSIX file
try
tell application "Finder"
if original item of file checkFile exists then
set targetFile to (original item of file checkFile) as alias
set posTargetFile to POSIX path of targetFile as text
get posTargetFile
end if
end tell
end try
-- END APPLESCRIPT --
HEREDOC;
$runText = "osascript << EOS\n{$getAliasTarget}\nEOS\n";
$target = trim( shell_exec( $runText ) );
return ( $target == "" ? false : true );
}
?>