Clearing content of text file using php

To add button you may use either jQuery libraries or simple Javascript script as shown below:

HTML link or button:

<a href="#" onClick="goclear()" id="button">click event</a>

Javascript:

<script type="text/javascript">
var btn = document.getElementById('button');
function goclear() { 
alert("Handler called. Page will redirect to clear.php");
document.location.href = "clear.php";
};
</script>

Use PHP to clear a file content. For instance you can use the fseek($fp, 0); or ftruncate ( resource $file , int $size ) as below:

<?php
//open file to write
$fp = fopen("/tmp/file.txt", "r+");
// clear content to 0 bits
ftruncate($fp, 0);
//close file
fclose($fp);
?>

Redirect PHP - you can use header ( string $string [, bool $replace = true [, int $http_response_code ]] )

<?php
header('Location: getbacktoindex.html');
?>

I hope it's help.

file_put_contents("filelist.txt", "");

You can redirect by using the header() function to modify the Location header.

This would truncate the file:

$fh = fopen( 'filelist.txt', 'w' );
fclose($fh);

In clear.php, redirect to the caller page by making use of $_SERVER['HTTP_REFERER'] value.

//create a file handler by opening the file
$myTextFileHandler = @fopen("filelist.txt","r+");

//truncate the file to zero
//or you could have used the write method and written nothing to it
@ftruncate($myTextFileHandler, 0);

//use location header to go back to index.html
header("Location:index.html");

I don't exactly know where u want to show the result.