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getlastmod

(PHP 4, PHP 5)

getlastmod — Gets time of last page modification

说明

int getlastmod ( void )

Gets the time of the last modification of the current page.

If you're interested in getting the last modification time of a different file, consider using filemtime().

返回值

Returns the time of the last modification of the current page. The value returned is a Unix timestamp, suitable for feeding to date(). Returns FALSE on error.

范例

Example #1 getlastmod() example

<?php
// outputs e.g. 'Last modified: March 04 1998 20:43:59.'
echo "Last modified: " . date ("F d Y H:i:s.", getlastmod());
?>

参见

PHP 选项/信息 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: Gets time of last page modification

用户评论:

luca dot delpivo at gmail dot com (12-Mar-2012 03:52)

With better words getlastmod() returning the last time the script in which it is being called was modified, it does not require or use a parameter.

erik dot stetina at gmail dot com (27-Sep-2011 11:47)

function for displaying last modification time accross more direcotries. e.g. to display last modification date in "about" section of your web page

<?php
function array_prefix_values($prefix, $array)
{
  $callback = create_function('$s','return "'.$prefix.'".$s;');
  return array_map($callback,$array);
}

function get_last_update()
{
  if ( func_num_args() < 1 ) return 0;
  $dirs = func_get_args();
  $files = array();
  foreach ( $dirs as $dir )
  {
    $subfiles = scandir($dir);
    $subfiles = array_prefix_values($dir,$subfiles);
    $subfiles = array_filter($subfiles,"is_file");
    $files = array_merge($files,$subfiles);
  }
  $maxtimestamp = 0;
  $maxfilename = "";
  foreach ( $files as $file )
  {
    $timestamp = filemtime($file);
    if ( $timestamp > $maxtimestamp )
    {
      $maxtimestamp = $timestamp;
      $maxfilename = $file;
    }
  }
  return date("Ymd",$maxtimestamp)." ($maxfilename)";
}

print "last update: ".get_last_update("./lib/", "./css/", "./lang/");
?>

OUTPUT:
last update: 20110927 (./lang/sk.php)

Ant P. (24-Feb-2010 06:48)

If you use register_shutdown_function() on certain SAPIs, various filesystem-related things inside the shutdown function might do unexpected things, one of which being this function can return false.

On the other hand getlastmod() apparently caches the return value, so if you use it at least once in normal code it should work for the remainder of the request.

rwruck (17-Oct-2004 02:28)

DO NOT use this function unless you are absolutely sure both your Apache and PHP have been compiled with the same value for -DFILE_OFFSET_BITS.

If not, this function will return the access time (or maybe even garbage) instead of the modification time due do Apache and PHP using different versions of the stat structure.

This is true regardless of Apache and PHP version.

To be on the safe side, always use the workaround already posted below:
filemtime($_SERVER['SCRIPT_FILENAME'])

(19-May-2004 12:36)

Setting the 'Last-Modified' header:
<?php
setlocale(LC_TIME, "C");
$ft = filemtime ('referencefile');
$localt = mktime ();
$gmtt = gmmktime ();
$ft = $ft - $gmtt + $localt;
$modified = strftime ("%a, %d %b %Y %T GMT", $ft);
?>

timeflys at users dot sourceforget dot net (20-Mar-2003 09:28)

I found issues using getlastmod() to test whether or not I was successful in setting the Last Modified date in the header. The code below shows the same Last Modified date before and after I set the Last-Modified header.

<?php
//True modified date
$modified = date ("F d Y H:i:s.", getlastmod());
   
//artificial modified date - sent to header
$last_modified = gmdate('D, d M Y H:i:s T', (time() - 43200));
    
//caching prevention
header("Last-Modified: $last_modified GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");  // HTTP/1.1
header("Cache-Control: post-check=0, pre-check=0", false);
    header("Pragma: no-cache");                          // HTTP/1.0

$getlast_modified = date ("F d Y H:i:s.", getlastmod());

print "True modified date(Before): $modified <p /> Date sent to header(After): $getlast_modified";
?>

I then used the PEAR, HTTP_Request class which worked, the Last-Modified date updates everytime it is requested, the desired effect.

<?php
require 'HTTP/Request.php';
$r = new HTTP_Request('http://www.sample.com/page.php');
$r->sendRequest();
$response_headers = $r->getResponseHeader();
print $response_headers["last-modified"];
?>

Richard Anderson(r85anderson at yahoo dot com) (17-Nov-2002 09:33)

for includes....

<?php
//include.php
$file = __FILE__;
$lastmod = date("M d, Y @ h:ia", filemtime($file));
?>

<?php
//footer.php
echo("page last modified: $lastmod");
?>

[EDIT by danbrown AT php DOT net: Remember that $lastmod must not be a variable that is set or unset anywhere else in the script, or it will not work as expected when printed from the footer.]

kworthington ([no@spam)] linuxmaildotorg (03-Oct-2002 11:33)

I was just informed of a workaround for the Apache 2.0 issue, do:
echo "Last modified: " . date("D F d Y h:i:s A", filemtime($_SERVER["SCRIPT_FILENAME"]));
Thanks to: Edward S. Marshall