How to get file creation date, modification date, access time in PHP

Common code for php to get file creation time and modification time

filemtime ( string filename )
返回文件上次被修改的时间，出错时返回 FALSE。时间以 Unix 时间戳的方式返回，可用于 date()。
例如：$a=filemtime("log.txt");
      echo "修改时间：".date("Y-m-d H:i:s",$a);
filectime ( string filename )
返回文件上次 inode 被修改的时间，如果出错则返回 FALSE。时间以 Unix 时间戳的方式返回。
例如：$a=filectime("log.txt");
      echo "创建时间：".date("Y-m-d H:i:s",$a);
fileatime ( string filename )
返回文件上次被访问的时间，如果出错则返回 FALSE。时间以 Unix 时间戳的方式返回。
例如：$a=fileatime("log.txt");
     echo "修改时间：".date("Y-m-d H:i:s",$a);

filemtime (string filename)

Returns the time when the file was last modified, and returns FALSE when an error occurs. The time is returned as a Unix timestamp, usable with date().

filectime (string filename)

Returns the time when the last inode of the file was modified, or FALSE if an error occurs. The time is returned as a Unix timestamp.

fileatime (string filename)

Returns the time when the file was last accessed, or FALSE if an error occurs. The time is returned as a Unix timestamp.

/////////////////////////////

filectime: linux last modification time
filemtime: last modification time
fileatime: last access time

////////////////////////////// ////////////////////////////////////////////////////

filemtime
(PHP 3, PHP 4)

filemtime -- Get file modification time
Description

int filemtime (string filename)

Returns the time when the file was last modified, and returns FALSE if an error occurs. The time is returned as a Unix timestamp, usable with date().
Note: The results of this function will be cached. See clearstatcache() for details.
Note: This function cannot be used on remote files. The files being checked must be accessed through the server's file system.
This function returns the time when the data block in the file was last written, that is, the time when the content of the file was last modified.

Example 1. filemtime() Example

<?php
// outputs e.g. somefile.txt was last modified: December 29 2002 22:16:23.
$filename = &#39;somefile.txt&#39;;
if (file_exists($filename)) {
 echo "$filename was last modified: " . date ("F d Y H:i:s.", filemtime($filename));
 
}
?>

filectime
(PHP 3, PHP 4)

filectime -- Get the inode modification time of the file
Explanation

int filectime (string filename)

Returns the time when the last inode of the file was modified, or FALSE if an error occurs. The time is returned as a Unix timestamp.
Note: In most Unix file systems, a file is considered modified when its inode data is changed. That is, when the file's permissions, owner, all groups, or other metadata in the inode are updated. See filemtime() (this is the function you want to use to create a "last updated" footer in a web page) and fileatime().
Note that some Unix instructions describe ctime as the time when the file was created, which is wrong. In most Unix file systems there is no creation time for Unix files.
Note: The results of this function will be cached. See clearstatcache() for details.
Note: This function cannot be used on remote files. The files being checked must be accessed through the server's file system.

Example 1. fileatime() Example

<?php
 
// 输出类似：somefile.txt was last changed: December 29 2002 22:16:23.
 
$filename = &#39;somefile.txt&#39;;
if (file_exists($filename)) {
 echo "$filename was last changed: " . date ("F d Y H:i:s.", filectime($filename));
}
?>

fileatime
(PHP 3, PHP 4)

fileatime -- Get the last access time of the file
Description

int fileatime (string filename)

Returns the time when the file was last accessed, or returns FALSE if an error occurs. The time is returned as a Unix timestamp.
Note: A file's atime should be changed whenever a block of data in the file is read. Performance is affected when an application regularly accesses a large number of files or directories. Some Unix file systems can turn off atime updates when loading to improve the performance of such programs. The USENET newsgroup spool is a common example. This function is useless in this file system.
Note: The results of this function will be cached. See clearstatcache() for details.
Note: This function cannot be used on remote files. The files being checked must be accessed through the server's file system.
Example 1. fileatime() example

<?php
// 输出类似：somefile.txt was last accessed: December 29 2002 22:16:23.
$filename = &#39;somefile.txt&#39;;
if (file_exists($filename)) {
 echo "$filename was last accessed: " . date ("F d Y H:i:s.", fileatime($filename));
}
?>

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