file_exists

(PHP 4, PHP 5, PHP 7)

file_exists — 检查文件或目录是否存在

说明

bool file_exists ( string $filename )

检查文件或目录是否存在。

参数

filename

文件或目录的路径。

在 Windows 中要用 //computername/share/filename 或者 \\computername\share\filename 来检查网络中的共享文件。

返回值

如果由 filename 指定的文件或目录存在则返回 TRUE，否则返回 FALSE。

Note:

This function will return FALSE for symlinks pointing to non-existing files.

Warning

如果因为安全模式的限制而导致不能访问文件的话，该函数会返回 FALSE。然而，可以使用 include 来包含，如果文件在 safe_mode_include_dir 所指定的目录里。

Note:

The check is done using the real UID/GID instead of the effective one.

Note: 因为 PHP 的整数类型是有符号整型而且很多平台使用 32 位整型，对 2GB 以上的文件，一些文件系统函数可能返回无法预期的结果 。

范例

Example #1 测试一个文件是否存在

<?php
$filename = '/path/to/foo.txt';

if (file_exists($filename)) {
    echo "The file $filename exists";
} else {
    echo "The file $filename does not exist";
}
?>

错误／异常

失败时抛出E_WARNING警告。

注释

Note: 此函数的结果会被缓存。参见 clearstatcache() 以获得更多细节。

Tip

自 PHP 5.0.0 起, 此函数也用于某些 URL 包装器。请参见 支持的协议和封装协议以获得支持 stat() 系列函数功能的包装器列表。

参见

  • is_readable() - 判断给定文件名是否可读
  • is_writable() - 判断给定的文件名是否可写
  • is_file() - 判断给定文件名是否为一个正常的文件
  • file() - 把整个文件读入一个数组中

User Contributed Notes

vcoletti at tiscali dot it 26-Jul-2017 07:35
With PHP 7.0 on Ubuntu 17.04 and with the option allow_url_fopen=On, file_exists() returns always false when trying to check a remote file via HTTP.

So
        $url="http://www.somewhere.org/index.htm";
        if (file_exists($url)) echo "Wow!\n";
        else echo "missing\n";

returns always "missing", even for an existing URL.

I found that in the same situation the file() function can read the remote file, so I changed my routine in

        $url="http://www.somewhere.org/index.htm";
        if (false!==file($url)) echo "Wow!\n";
        else echo "missing\n";
               
This is clearly a bit slower, especially if the remote file is big, but it solves this little problem.
gwionps at gmail dot com 23-Aug-2016 09:56
I was using this function (and others related to files) naively. The following is possible:

<?php

$path = "../index.php";
if (file_exists("img/" . $path)) {
  echo file_get_contents("img/" . $path);
}

?>

I know it's naive, but it's worth noting!
ziptwipi at goioia dot com 18-Aug-2016 02:44
Note that realpath() will return false if the file doesn't exist. So if you're going to absolutize the path and resolve symlinks anyway, you can just check the return value from realpath() instead of calling file_exists() first
aaoun at sabis dot net 17-Dec-2015 07:15
Does not work for filename containing Arabic
mirza4jobs at gmail dot com, Mirza Qasim Ali 17-Nov-2015 04:32
//Mirza Qasim Ali Script DF
checkRemoteFile('www.ab.com/images/image.jpg');
function checkRemoteFile($url)
{
   $file = $url;
   $file_headers = @get_headers($file);
  
   
   
    switch($file_headers[0])
    {
        case 'HTTP/1.1 404 Not Found':
        return false;
        break;
       
        case 'HTTP/1.1 302 Moved Temporarily':
        return false;
        break;
       
        default:
        return true;
       
        }
}
broken at links dot com 14-May-2014 09:29
file_exists() will return FALSE for broken links

$ ln -s does_not_exist my_link
$ ls -l
lrwxr-xr-x   1 user  group    14 May 13 17:28 my_link -> does_not_exist
$ php -r "var_dump(file_exists('my_link'));"
bool(false)
welkom at remconijhuis dot nl 30-Dec-2013 08:10
I needed to measure performance for a project, so I did a simple test with one million file_exists() and is_file() checks. In one scenario, only seven of the files existed. In the second, all files existed. is_file() needed 3.0 for scenario one and 3.3 seconds for scenario two.  file_exists() needed 2.8 and 2.9 seconds, respectively. The absolute numbers are off course system-dependant, but it clearly indicates that file_exists() is faster.
junya 06-Jan-2013 09:11
On Japanese Windows system, here is the other way to figure out the file existence to avoid SJIS 5C problem.

<?php
function sjis_file_exists($filename)
{
    return exec("if exist \"$filename\" (echo 1) else (echo 0)");
}
?>
DeyV at poczta dot php dot pl 13-Jan-2012 01:47
Great alternative to file_exists() is stream_resolve_include_path()
www dot freev at gmail dot com 27-Jul-2011 03:17
my function filexists() function search file firts in include_path:
<?php
function filexists($file)
{
  $ps = explode(":", ini_get('include_path'));
  foreach($ps as $path)
  {
    if(file_exists($path.'/'.$file)) return true;
  }
  if(file_exists($file)) return true;
  return false;
}
?>
spark at limao dot com dot br 13-Apr-2011 04:26
this code here is in case you want to check if a file exists in another server:

<?php
function fileExists($path){
    return (@fopen($path,"r")==true);
}
?>

unfortunately the file_exists can't reach remote servers, so I used the fopen function.
_ michael 05-Sep-2010 11:16
There is a subtle difference in behaviour of file_exists(), depending on the OS. Suppose you test a path ending with a slash. If the corresponding filesystem object exists, but is not a directory but a file, file_exists() will return true on Windows and false on Linux.

Ie, file_exists( $path_from_root . '/somedir/file/' ) returns true on Windows if that file exists, and false on Linux.

Tested with PHP 5.3.3 on Ubuntu and PHP 5.2.9 on Windows.
hex 07-May-2010 08:11
If you simply want to check that some file (not directory) exists, and concerned about performance, try is_file() instead.
I timed is_file and file_exists, it seems like is_file() is almost 2x faster when a file exists and about the same when it doesn't.
ferodano at gmail dot com 16-Sep-2009 10:54
You could use document root to be on the safer side because the function does not take relative paths:

<?php
if( file_exists( $_SERVER{'DOCUMENT_ROOT'} . "/my_images/abc.jpg"))  {
   ...
}
?>

Do not forget to put the slash '/', e.g. my doc root in Ubuntu is /var/www without the slash.
pgl at yoyo dot org 31-Jul-2009 04:03
Note that this will return false for streams, eg, php://stdin.
jbeltran 20-May-2009 10:39
I want to warn developers using PHP 5.0.4 of a bug that don't happen in current stable versions:

file_exists seems to cache the response, even when the file has been moved.

An example:
<?php
/*
    When a file which has been called by file_exist
    has been moved, the file_exist next call gives true again

*/
$f = "foo.txt";
file_put_contents( $f, "content" );
if(file_exists( $f )){
    rename( $f, $f.".moved" );
}
if( file_exists( $f )){
    echo "Wrong! the file has just been moved! file_exists should return false.";
    rename( $f, $f.".willnotwork" ); //It gives a warning
}
?>

The same code tested in PHP 5.2.4-2ubuntu5.6 with Suhosin-Patch 0.9.6.2 (cli) behaves correctly.
alkaaran at gmail dot com 02-Feb-2009 03:11
Although PHP 5+ supports this function with FTP, it appears that file_exists() used on ftp will always return TRUE, even if the file or directory does not exist.
fabin dot gnu at gmail dot com 31-Jan-2009 10:03
The code can be used to t a filename that can be used to create a new filename.

<?php
function generateRandomString($length = 8)
{   
    $string = "";
   
    //character that can be used
    $possible = "0123456789bcdfghjkmnpqrstvwxyz";
   
    for($i=0;$i < $length;$i++)
    {
        $char = substr($possible, rand(0, strlen($possible)-1), 1);
       
        if (!strstr($string, $char))
        {
            $string .= $char;
        }
    }

    return $string;
}

function randomFile($folder = '', $extension = '')
{
    $folder = trim($folder);
    $folder = ($folder == '') ? './' : $folder;
 
    //check if directory exist
    if (!is_dir($folder)){ die('invalid folder given!'); }
 
    //generate a filepath
    $filepath = $folder . "/" . generateRandomString(128) . $extension;
   
    //check if that filepath already exist, if it exist if generates again
    //till if gets one that doesn't exist
    while(file_exists($filepath))
    {
        $filepath = $folder . "/" . generateRandomString(128) . $extension;
    }
   
    return $filepath;
}
?>
kevin at cuznersoft dot com 04-Nov-2008 05:32
My way of making sure files exist before including them is as follows (example: including a class file in an autoloader):

<?php
function __autoload($name)
{   
    $path = explode(":", ini_get('include_path')); //get all the possible paths to the file (preloaded with the file structure of the project)
    foreach($path as $tryThis)
    {
        //try each possible iteration of the file name and use the first one that comes up
        // name.class.php first
        $exists = file_exists($tryThis . '/' . $name . '.class.php');
        if ($exists)
        {
            include_once($name . '.class.php');
            return;
        }
       
        //ok that didn't work, try the other way around
        $exists = file_exists($tryThis . '/' . 'class.' . $name . '.php');
        if ($exists)
        {
            include_once('class.' . $name . '.php');
            return;
        }
       
        //neither did that...let's try as an inc.php
        $exists = file_exists($tryThis . '/' . $name . '.inc.php');
        if ($exists)
        {
            include_once($name . '.inc.php');
            return;
        }
    }
   
   
    // can't find it...
    die("Class $name could not be found!");
}
?>
justin 21-Aug-2008 09:07
Small adjustment to the url_exist() by marufit at gmail dot com.  Some sites like digg.com for example check the HTTPHEADER to see who is requesting the page and will PHP will throw an error.  Adding the following line fixes the issue:

curl_setopt($handle, CURLOPT_HTTPHEADER, Array("User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.15) Gecko/20080623 Firefox/2.0.0.15") ); // request as if Firefox   

<?php
function url_exists($url) {
    // Version 4.x supported
    $handle   = curl_init($url);
    if (false === $handle)
    {
        return false;
    }
    curl_setopt($handle, CURLOPT_HEADER, false);
    curl_setopt($handle, CURLOPT_FAILONERROR, true);  // this works
    curl_setopt($handle, CURLOPT_HTTPHEADER, Array("User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.15) Gecko/20080623 Firefox/2.0.0.15") ); // request as if Firefox   
    curl_setopt($handle, CURLOPT_NOBODY, true);
    curl_setopt($handle, CURLOPT_RETURNTRANSFER, false);
    $connectable = curl_exec($handle);
    curl_close($handle);  
    return $connectable;
}
?>
Avee 19-Aug-2008 05:21
I made a bit of code that sees whether a file served via RTSP is there or not:

<?php
function rtsp_exists($url) {

    $server = parse_url($url, PHP_URL_HOST);
    $port = "554";
    $hdrs = "DESCRIBE " .$url ." RTSP/1.0"."\r\n\r\n";

    //Open connection (15s timeout)
    $sh = fsockopen($server, $port, $err, $err_otp, 15);
    //Check connections
    if(!$sh) return false;
    //Send headers
    fputs($sh,$hdrs);
    //Receive data (1KB)
    $rtds = fgets($sh, 1024);
    //Close socket
    fclose($sh);

    return strpos($rtds, "200 OK") > 0;
}
?>
dan at sudonames dot com 06-Aug-2008 02:41
Here is a simpler version of url_exists:

<?php
function url_exists($url) {
    $hdrs = @get_headers($url);
    return is_array($hdrs) ? preg_match('/^HTTP\\/\\d+\\.\\d+\\s+2\\d\\d\\s+.*$/',$hdrs[0]) : false;
}
?>
stuart 26-Feb-2008 07:44
When using file_exists, seems you cannot do:

<?php
foreach ($possibles as $poss)
{
    if ( file_exists(SITE_RANGE_IMAGE_PATH .$this->range_id .'/ '.$poss .'.jpg') )
    {
        // exists
    }
    else
    {
        // not found
    }
}
?>

so you must do:

<?php
foreach ($possibles as $poss)
{
    $img = SITE_RANGE_IMAGE_PATH .$this->range_id .'/ '.$poss .'.jpg'
    if ( file_exists($img) )
    {
        // exists
    }
    else
    {
        // not found
    }
}
?>

Then things will work fine.

This is at least the case on this Windows system running php 5.2.5 and apache 2.2.3

Not sure if it is down to the concatenation or the fact theres a constant in there, i'm about to run away and test just that...
jaz-t at hotmail dot com 26-Feb-2008 04:12
Note on openspecies entry (excellent btw, thanks!).

If your server cannot resolve its own DNS, use the following:
$f = preg_replace('/www\.yourserver\.(net|com)/', getenv('SERVER_ADDR'), $f);

Just before the $h = @get_headers($f); line.

Replace the extensions (net|com|...) in the regexp expression as appropriate.

EXAMPLE:
File you are checking for: http://www.youserver.net/myfile.gif
Server IP: 10.0.0.125

The preg_replace will effectively 'resolve' the address for you by assigning $f as follows:
http://10.0.0.125/myfile.gif
maurice at idify dot nl 20-Nov-2007 11:45
Note: The results of this function are cached. See clearstatcache() for more details.

That's a pretty big note. Don't forget this one, since it can make your file_exists() behave unexpectedly - probably at production time ;)
marufit at gmail dot com 12-Nov-2007 12:22
Older php (v4.x) do not work with get_headers() function. So I made this one and working.

<?php
function url_exists($url) {
    // Version 4.x supported
    $handle   = curl_init($url);
    if (false === $handle)
    {
        return false;
    }
    curl_setopt($handle, CURLOPT_HEADER, false);
    curl_setopt($handle, CURLOPT_FAILONERROR, true);  // this works
    curl_setopt($handle, CURLOPT_NOBODY, true);
    curl_setopt($handle, CURLOPT_RETURNTRANSFER, false);
    $connectable = curl_exec($handle);
    curl_close($handle);   
    return $connectable;
}
?>
ktcb123 at hotmail dot com 22-Oct-2007 09:26
For some reason, none of the url_exists() functions posted here worked for me, so here is my own tweaked version of it.

<?php
    function url_exists($url){
        $url = str_replace("http://", "", $url);
        if (strstr($url, "/")) {
            $url = explode("/", $url, 2);
            $url[1] = "/".$url[1];
        } else {
            $url = array($url, "/");
        }

        $fh = fsockopen($url[0], 80);
        if ($fh) {
            fputs($fh,"GET ".$url[1]." HTTP/1.1\nHost:".$url[0]."\n\n");
            if (fread($fh, 22) == "HTTP/1.1 404 Not Found") { return FALSE; }
            else { return TRUE;    }

        } else { return FALSE;}
    }
?>
guillermogomezruiz at gmail dot com 07-Sep-2007 01:08
I was having problems with the file_exists when using urls, so I made this function:

<?php
function file_exists_2($filePath)
{
    return ($ch = curl_init($filePath)) ? @curl_close($ch) || true : false;
}
?>

Cheers!
worldclimb at gmail dot com 19-Jul-2007 11:48
Small error in florinel2k's example

$sourcePath should be $fileUrl, otherwise it works well for me.

//Corrected
This is an example if you want to know that a file exists (if that file isn't on your server):

$fileUrl = "http://www.examplecom/test.jpg";
$AgetHeaders = @get_headers($fileUrl);
if (preg_match("|200|", $AgetHeaders[0])) {
// file exists
} else {
// file doesn't exists
}
pcdinh at phpvietnam dot net 14-Jul-2007 04:03
In response to havran at gmail dot com

Your function url_exists() does not work because it has got a big bug. curl_init does not make a connection to that url until curl_exec() is executed. The return value from curl_init() shows if a curl session can be started.

That function can be rewritten as follows

<?php
class Url
{
    /**
     * Check if an url is existed
     *
     * @param  string    $url
     * @access static
     * @return bool      True if the url is accessible and false if the url is unaccessible or does not exist
     * @throws Exception An exception will be thrown when Curl session fails to start
     */
    public static function exists($url)
    {
        if (null === $url || '' === trim($url))
        {
            throw new Exception('The url to check must be a not empty string');
        }
       
        $handle   = curl_init($url);

        if (false === $handle)
        {
            throw new Exception('Fail to start Curl session');
        }

        curl_setopt($handle, CURLOPT_HEADER, false);
        curl_setopt($handle, CURLOPT_NOBODY, true);
        curl_setopt($handle, CURLOPT_RETURNTRANSFER, false);

        // grab Url
        $connectable = curl_exec($handle);

        // close Curl resource, and free up system resources
        curl_close($handle);   
        return $connectable;
    }
}
?>

How to use:

<?php

try
{
    if (Url::exists('http://phpvietnam.net'))
    {
        // Do something here   
    }
}
catch (Exception $ex)
{
    // Do something here
}

?>
bvazquez at siscomx dot com 04-Jul-2007 06:13
If you are trying to access a Windows Network Share you have to configure your WebServer with enough permissions for example:

$file = fopen("\\siscomx17\c\websapp.log",'r');

You will get an error telling you that the pathname doesnt exist this will be because Apache or IIS run as LocalSystem so you will have to enter to Services and configure Apache on "Open a session as" Create a new user that has enough permissions and also be sure that target share has the proper permissions.

Hope this save some hours of research to anyone.
florinel2k at yahoo dot com 13-Jun-2007 10:23
This is an example if you want to know that a file exists (if that file isn't on your server):

$fileUrl = "http://www.examplecom/test.jpg";
$AgetHeaders = @get_headers($sourcePath);
if (preg_match("|200|", $AgetHeaders[0])) {
// file exists
} else {
// file doesn't exists
}
vernon at kesnerdesigns dot net 10-May-2007 05:44
In response to seejohnrun's version to check if a URL exists. Even if the file doesn't exist you're still going to get 404 headers.  You can still use get_headers if you don't have the option of using CURL..

$file = 'http://www.domain.com/somefile.jpg';
$file_headers = @get_headers($file);
if($file_headers[0] == 'HTTP/1.1 404 Not Found') {
    $exists = false;
}
else {
    $exists = true;
}
havran at gmail dot com 12-Apr-2007 07:56
Function url_exists() through CURL.

<?php
function url_exists($url) {
    if (!$fp = curl_init($url)) return false;
    return true;
}
?>
earle dot west at transactionalweb dot com 15-Mar-2007 02:49
If the file being tested by file_exists() is a file on a symbolically-linked directory structure, the results depend on the permissions of the directory tree node underneath the linked tree.   PHP under a web server (i.e. apache) will respect permissions of the file system underneath the symbolic link, contrasting with PHP as a shell script which respects permissions of the directories that are linked (i.e. on top, and visible).  

This results in files that appear to NOT exist on a symbolic link, even though they are very much in existance and indeed are readable by the web server.
pilotdoofy at gmail dot com 22-Apr-2006 10:35
I wrote a very simple function that allows you to search a folder for a file name with a regular expression. It can handle both PREG and EREG regexps and can accept different case sensitivities for EREG regexps.

function regExpFile($regExp, $dir, $regType='P', $case='') {
# Two parameters accepted by $regType are E for ereg* functions
# and P for preg* functions
$func = ( $regType == 'P' ) ? 'preg_match' : 'ereg' . $case;

# Note, technically anything other than P will use ereg* functions;
# however, you can specify whether to use ereg or eregi by
# declaring $case as "i" to use eregi rather than ereg

$open = opendir($dir);
while( ($file = readdir($open)) !== false ) {
if ( $func($regExp, $file) ) {
return true;
}
} // End while
return false;
} // End function

Basically if you supply anything but "P" for $regType it will assume you're using EREG regexps. The case should only be blank or "i".
07-Jan-2006 10:08
I wrote this little handy function to check if an image exists in a directory, and if so, return a filename which doesnt exists e.g. if you try 'flower.jpg' and it exists, then it tries 'flower[1].jpg' and if that one exists it tries 'flower[2].jpg' and so on. It works fine at my place. Ofcourse you can use it also for other filetypes than images.

<?php
function imageExists($image,$dir) {

    $i=1; $probeer=$image;

    while(file_exists($dir.$probeer)) {
        $punt=strrpos($image,".");
        if(substr($image,($punt-3),1)!==("[") && substr($image,($punt-1),1)!==("]")) {
            $probeer=substr($image,0,$punt)."[".$i."]".
            substr($image,($punt),strlen($image)-$punt);
        } else {
            $probeer=substr($image,0,($punt-3))."[".$i."]".
            substr($image,($punt),strlen($image)-$punt);
        }
        $i++;
    }
    return $probeer;
}
?>
Fabrizio (staff at bibivu dot com) 22-Dec-2005 03:11
here a function to check if a certain URL exist:
<?php
    function url_exists($url) {
        $a_url = parse_url($url);
        if (!isset($a_url['port'])) $a_url['port'] = 80;
        $errno = 0;
        $errstr = '';
        $timeout = 30;
        if(isset($a_url['host']) && $a_url['host']!=gethostbyname($a_url['host'])){
            $fid = fsockopen($a_url['host'], $a_url['port'], $errno, $errstr, $timeout);
            if (!$fid) return false;
            $page = isset($a_url['path'])  ?$a_url['path']:'';
            $page .= isset($a_url['query'])?'?'.$a_url['query']:'';
            fputs($fid, 'HEAD '.$page.' HTTP/1.0'."\r\n".'Host: '.$a_url['host']."\r\n\r\n");
            $head = fread($fid, 4096);
            fclose($fid);
            return preg_match('#^HTTP/.*\s+[200|302]+\s#i', $head);
        } else {
            return false;
        }
    }
?>

in my CMS, I am using it with those lines:
<?php
        if(!isset($this->f_exist[$image]['exist']))
            if(strtolower(substr($fimage,0,4)) == 'http' || strtolower(substr($fimage,0,4)) == 'www.'){
                if(strtolower(substr($image,0,4)) == 'www.'){
                    $fimage = 'http://'.$fimage;
                    $image = 'http://'.$image;
                }
                $this->f_exist[$image]['exist'] = $this->url_exists($fimage); //for now
            } else {
                $this->f_exist[$image]['exist'] = ($fimage!='' && file_exists($fimage) && is_file($fimage) && is_readable($fimage) && filesize($fimage)>0);
            }
        }
?>
ihoss dot com at gmail dot com 19-Oct-2005 04:37
The following script checks if there is a file with the same name and adds _n to the end of the file name, where n increases. if img.jpg is on the server, it tries with img_0.jpg, checks if it is on the server and tries with img_1.jpg.
<?php
  $img = "images/".$_FILES['bilde']['name'];
  $t=0;
  while(file_exists($img)){
    $img = "images/".$_FILES['bilde']['name'];
    $img=substr($img,0,strpos($img,"."))."_$t".strstr($img,".");
    $t++;
  }
  move_uploaded_file($_FILES['bilde']['tmp_name'], $img);
?>
phenbach at phenbach dot com 20-Sep-2005 12:37
I recently had an issue with PLESK and copying file to other directories with the move_uploaded file function.

This would work on every linux server except plesk servers. I could figure it out and have yet to find out.  I had to create a work a round and decided to use the exec() function.

As noted above the file_exist() function must need to wait for some time and I found the looking function a waste of resouces and didn't work for me anyway. So this is what I came up with.

function cp($source,$destination){

$cmd="cp -u ".$source ." ".$destination; //create the command string to copy with the update option
exec($cmd); //exec command
$cmd_test="ls -la ".$destination; //list file
exec($cmd_test,$out);
//If the file is present it $out[0] key will contain the file info.
//if it is not present it will be null
if (isset($out[0])){
     return true;
}else{
     return false;
}
    }
tma at 2p dot cz 24-Aug-2005 10:47
If checking for a file newly created by an external program in Windows then file_exists() does not recognize it immediately.  Iy seems that a short timeout may be required.

<?
    $file = 'file.tmp';
    if ($h = popen("start \"bla\" touch $file", "r")) {
      pclose($h);
   // now I would like know if a file was created
   // note: usleep not supported
      $start = gettimeofday();  
      while (!file_exists(trim($file, " '\""))) {
        $stop = gettimeofday();
        if ( 1000000 * ($stop['sec'] - $start['sec']) + $stop['usec'] - $start['usec'] > 500000) break;  // wait a moment
     }

     if (file_exists($file))   // now should be reliable
?>
09-Aug-2005 04:20
That is true feshi. But, if you have your server configured correctly, those access logs will only be accessible by an admin or the root account. The webuser account that runs the php script will be unable to start reading from that file. That's the easiest fix.
07-Mar-2005 11:00
Nathaniel, you should read the manual carefuly next time prior to posting anything here, as all you indicated is the fact you missed the idea of the include_path. To remind - include_path is for some functions only, mainly intended for include and require to simpify include/require operations (kinda way the #include works). It is NOT for any filesystem function, which would be damn annoying than helpful, which is quite understandable and obvious.
andrewNOSPAMPLEASE at abcd dot NOSPAMERSca 11-Feb-2005 02:29
file_exists will have trouble finding your file if the file permissions are not read enabled for 'other' when not owned by your php user. I thought I was having trouble with a directory name having a space in it (/users/andrew/Pictures/iPhoto Library/AlbumData.xml) but the reality was that there weren't read permissions on Pictures, iPhoto Library or AlbumData.xml. Once I fixed that, file_exists worked.
Nathaniel 09-Feb-2005 06:08
I spent the last two hours wondering what was wrong with my if statement: file_exists($file) was returning false, however I could call include($file) with no problem.

It turns out that I didn't realize that the php include_path value I had set in the .htaccess file didn't carry over to file_exists, is_file, etc.

Thus:

<?PHP
// .htaccess php_value include_path '/home/user/public_html/';

// includes lies in /home/user/public_html/includes/

//doesn't work, file_exists returns false
if ( file_exists('includes/config.php') )
{
     include('includes/config.php');
}

//does work, file_exists returns true
if ( file_exists('/home/user/public_html/includes/config.php') )
{
    include('includes/config.php');
}
?>

Just goes to show that "shortcuts for simplicity" like setting the include_path in .htaccess can just cause more grief in the long run.
alex at raynor nospam dot ru 05-Apr-2004 05:16
If you use open_basedir in php.ini and use file_exists for file outside open_basedir path, you will not be warned at log and file_exists returns false even if file really exists.