note 69375 deleted from function.file-exists by colder

Note Submitter: info at g2data dot com Reason: in docs ---- You'd think such a simple test would be simple, but oh no. I found that sometimes file_exists can return true when a file does NOT exist. But there is a reason for this (as I finally found): I used the following script to test this problem I was having on PHP5.x on Debian Sarge, Ubuntu Hoary & Windows. On Ubuntu & Sometimes Windows, the script continued to say $doc existed even though it definitely did not. <?php $doc = 'tmp/test.doc'; if (!is_dir('tmp')) { mkdir('tmp'); // create a tmp dir if it doesn't already exist } touch($doc); // Create a doc if (file_exists($doc)) { // test if file exists: echo "file_exists function returned: TRUE ". $doc ." EXISTS:<br />"; } else { echo $doc ." Don't Exists<br />"; } // manually confirm file exists by examining the output of the system DIR/ls (depending on your OS) echo "<pre>PRE rm: ". $doc ."<br />"; echo system(($_ENV['OS']? 'DIR tmp':'ls tmp')); echo "</pre>"; // Now issue a system command to DEL/rm the doc you created (depending on your OS) exec(($_ENV['OS']? 'DEL "'. str_replace('/','\\',$doc) .'"':'rm "'. $doc .'"')); // Now look at output from a system DIR/ls of the tmp dir. It should show no sign of test.doc anymore. echo "<pre>POST rm: ". $doc ."<br />"; echo system(($_ENV['OS']? 'DIR tmp':'ls tmp')); echo "</pre>"; // now test for the existance of $doc. if (file_exists($doc)) { echo "file_exists function returned: TRUE ". $doc ." <strong>STILL EXISTS!!!</strong><br />"; } else { echo $doc ." DELETED<br />"; } // On Ubuntu and occasionally the windows box, this test would return true for the second test, despite the fact we had without doubt deleted $doc prior to this second file_exists($doc) test. ?> After much head scratching I discovered the answer to this problem is to use: clearstatcache(); If you change the contents of a file/dir in some way just prior to using file_exists (and others shown below), file_exists returns the value of what's in the statcache, which might not reflect the whole truth. To avoid getting a true, when it should be a false, use clearstatcache prior to your test. Affected functions include: stat(), lstat(), file_exists(), is_writable(), is_readable(), is_executable(), is_file(), is_dir(), is_link(), filectime(), fileatime(), filemtime(), fileinode(), filegroup(), fileowner(), filesize(), filetype(), and fileperms().