You want to know when a file was last accessed or changed, or you want to update a file's access or change time; for example, you want each page on your web site to display when it was last modified.
The fileatime( ), filemtime( ), and filectime( ) functions return the time of last access, modification, and metadata change of a file, as shown in Example 24-5.
Getting file timestamps
A file's modification time can be updated with touch( ). Without a second argument, touch( ) sets the modification time to the current date and time. To set a file's modification time to a specific value, pass that value as an epoch timestamp to touch( ) as a second argument. Example 24-6 changes the modification time of two files without changing their contents.
Changing file modification times
The fileatime( ) function returns the last time a file was opened for reading or writing. The filemtime( ) function returns the last time a file's contents were changed. The filectime( ) function returns the last time a file's contents or metadata (such as owner or permissions) were changed. Each function returns the time as an epoch timestamp.
The code in Example 24-7 prints the time a page on your web site was last updated.
Printing web page modification times
24.1.4. See Also
Documentation on fileatime( ) at http://www.php.net/fileatime, filemtime( ) at http://www.php.net/filemtime, and filectime( ) at http://www.php.net/filectime.