How do I prepend file to begining??

Question

In PHP if you write to a file it will write end of that existing file. but how do we prepend a file to write in the beginning of that file??

I have tried rewind($handle) function but seems over writing if current content is larger than existing...

Any Ideas??

Answer 1

$prepend = 'prepend me please';

$file = '/path/to/file';

$fileContents = file_get_contents($file);

file_put_contents($file, $prepend . $fileContents);

Answer 2

When using fopen() you can set the mode to set the pointer (ie. the begginng or end.

$afile = fopen("file.txt", "r+");

'r' Open for reading only; place the file pointer at the beginning of the file.

'r+' Open for reading and writing; place the file pointer at the beginning of the file.

Answer 3

The file_get_contents solution is inefficient for large files. This solution may take longer, depending on the amount of data that needs to be prepended (more is actually better), but it won't eat up memory.

<?php

$cache_new = "Prepend this"; // this gets prepended
$file = "file.dat"; // the file to which $cache_new gets prepended

$handle = fopen($file, "r+");
$len = strlen($cache_new);
$final_len = filesize($file) + $len;
$cache_old = fread($handle, $len);
rewind($handle);
$i = 1;
while (ftell($handle) < $final_len) {
  fwrite($handle, $cache_new);
  $cache_new = $cache_old;
  $cache_old = fread($handle, $len);
  fseek($handle, $i * $len);
  $i++;
}
?>

Answer 4

Another (rough) suggestion:

$tempFile = tempnam('/tmp/dir');
$fhandle = fopen($tempFile, 'w');
fwrite($fhandle, 'string to prepend');

$oldFhandle = fopen('/path/to/file', 'r');
while (($buffer = fread($oldFhandle, 10000)) !== false) {
    fwrite($fhandle, $buffer);
}

fclose($fhandle);
fclose($oldFhandle);

rename($tempFile, '/path/to/file');

This has the drawback of using a temporary file, but is otherwise pretty efficient.