PHP: How to delete last N bytes from large file?

Question

I have a large file and need to delete last 512 bytes. I don't want to duplicate file.

Thanks.

Answer 1

Usage example with fstat, ftruncate, fopen and fclose:

<?php    

$bytesToTruncate = 5; // how many bytes we are going to delete from the end of the file

$handle = fopen('/home/francesco/mytest', 'r+'); // Open for reading and writing; place the file pointer at the beginning of the file.

$stat = fstat($handle);
$size = $stat['size'] - $bytesToTruncate;
$size = $size < 0 ? 0 : $size;

ftruncate($handle, $size);
fclose($handle);

• http://www.php.net/manual/en/function.fopen.php
• http://www.php.net/manual/en/function.fstat.php
• http://www.php.net/manual/en/function.ftruncate.php
• http://www.php.net/manual/en/function.fclose.php

Answer 2

You should use ftruncate(handle, file_size - 512) (get the file size with filesize or fstat function)

Answer 3

I haven't tested it with large files but you can give it a try:

• http://es.php.net/filesize
• http://es.php.net/ftruncate