PHP | touch( ) function

The touch() function in PHP is an inbuilt function which is used setting the access and modification time of a specified file.
The filename of the file whose access and modification time has to be set is sent as a parameter along with the time to the touch() function and it returns True on success and False on failure. A file is created first if it doesn’t exist.

Syntax:

touch(filename, time, atime)

Parameters Used:
The touch() function in PHP accepts three parameters.

1. filename : It is a mandatory parameter which specifies the filename of the file whose access and modification time have to be changed.
2. time : It is an optional parameter which specifies the time.By default it takes the current system time.
3. atime : It is an optional parameter which specifies the access time. By default it takes the current system time if no parameters are set.

Return Value:
It returns True on success and False on failure.

Errors And Exception

1. The time resolution may differ from one file system to another therefore you may get unexpected results sometimes.
2. The $time parameter in the touch() function has a future limit around 1000000 seconds.
3. The touch() function used on a directory returns FALSE and prints “Permission denied” on NTFS and FAT Filesystem.

Examples:

Input : $file_pointer = "gfg.txt";
        if (touch($file_pointer)) 
        {
           echo ("$file_pointer modification time has been set to current system time.");
        } 
        else 
        {
           echo ("$file_pointer modification time cannot be changed.");
        }
Output :gfg.txt modification time has been set to current system time.

Input : $file_pointer = "gfg.txt";
        $time = time() - 18000;
        if (touch($file_pointer, $time)) 
        {
           echo ("$file_pointer modification time has been changed to 5 hours in the past.");
        } 
        else 
        {
           echo ("$file_pointer modification time cannot be changed.");
        }

Output : gfg.txt modification time has been changed to 5 hours in the past.

Below programs illustrate the touch() function.

Suppose there is a file named “gfg.txt”

Program 1

<?php
$file_pointer = "gfg.txt";
// using touch() function to change the modification
// time of a file to current system time
if (touch($file_pointer))
{
   echo ("$file_pointer modification time has been set to current system time.");
}
else
{
   echo ("$file_pointer modification time cannot be changed.");
}

?>

Output:

gfg.txt modification time has been set to current system time.

Program 2

<?php
$file_pointer = "gfg.txt";

// setting touch time to 5 hours in the past
$time = time() - 18000;

// using touch() function to change the modification
// time of a file to current system time
if (touch($file_pointer, $time))
{
    echo ("$file_pointer modification time has been changed to 5 hours in the past.");
 }
else
{
   echo ("$file_pointer modification time cannot be changed.");
}

?>

Output:

gfg.txt modification time has been changed to 5 hours in the past.

Reference:
http://php.net/manual/en/function.touch.php