note 40601 added to function.filemtime

Be warned that depending on your hosting service, it may happen that files created by touch () and by fopen () may not have the same filemtime () and/or filectime. See below for some test code. Also, when a file is uploaded through FTP, its creation/modification date may be "fopen-like" or "touch-like"... You will have to test. This could lead to trouble for cache systems (quite annoying bugs, hard to find and long to fix and test) or other time-dependant code (importing files if more recent than some other, etc.). Finally, I've seen new files having different file times depending on their path... Specifically, one file created in my web directory and another one in a temp directory (using tempnam ()) have some 12 minutes file time difference! And now for some test code : <? function showFileTimesAndUnlink ($fileName) { clearstatcache (); echo 'filemtime : ' . date ('r', filemtime ($fileName)) . '<br />'; echo 'filectime : ' . date ('r', filectime ($fileName)) . '<br />'; unlink ($fileName); } function showTimes ($tmpFileName) { echo 'Touch file : ' . $tmpFileName . '<br />'; touch ($tmpFileName); showFileTimesAndUnlink ($tmpFileName); echo 'Fopen file : ' . $tmpFileName . '<br />'; $f = fopen ($tmpFileName, 'w+'); fclose ($f); showFileTimesAndUnlink ($tmpFileName); } echo 'Date : ' . date ('r') . '<br />'; $tmpFileName = tempnam ($_SERVER['DOCUMENT_ROOT'], ''); showTimes ($tmpFileName); $tmpFileName = tempnam ('', ''); showTimes ($tmpFileName); ?> ..giving on my host the following result : Date : Tue, 9 Mar 2004 12:12:43 +0100 Touch file : /home/site/www/qpTkZH filemtime : Tue, 9 Mar 2004 12:12:43 +0100 filectime : Tue, 9 Mar 2004 11:59:46 +0100 Fopen file : /home/site/www/qpTkZH filemtime : Tue, 9 Mar 2004 11:59:46 +0100 filectime : Tue, 9 Mar 2004 11:59:46 +0100 Touch file : /tmp/sC0ZUU filemtime : Tue, 9 Mar 2004 12:12:43 +0100 filectime : Tue, 9 Mar 2004 12:12:43 +0100 Fopen file : /tmp/sC0ZUU filemtime : Tue, 9 Mar 2004 12:12:43 +0100 filectime : Tue, 9 Mar 2004 12:12:43 +0100 Workaround : you may touch () all the files you're going to check using filmtime after they've been updated using fopen (). Or you may use some custom touchFile () function instead of touch (). Here's mine : it opens the file, appends nothing to it, and closes it. <? function touchFile ($fileName) { $f = fopen ($fileName, 'a+'); fclose ($f); } ?> ..thus, my filemtime and filectime are always the "fopen" ones. Still, files created in /tmp and ones created in /home/etc. are not the same. Well, I guess there's some special mechanism in the kernel for temp files, maybe build for performance reasons. ---- Manual Page -- http://www.php.net/manual/en/function.filemtime.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+40601 Delete -- http://master.php.net/manage/user-notes.php?action=delete+40601&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+40601&report=yes Search -- http://master.php.net/manage/user-notes.php