How do I prepend file to beginning?

In PHP if you write to a file it will write end of that existing file.

How do we prepend a file to write in the 开发者_如何学Cbeginning of that file?

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

Any Ideas?

---

$prepend = 'prepend me please';

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

$fileContents = file_get_contents($file);

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

---

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++;
}
?>

---

$filename  = "log.txt";
$file_to_read = @fopen($filename, "r");
$old_text = @fread($file_to_read, 1024); // max 1024
@fclose(file_to_read);
$file_to_write = fopen($filename, "w");
fwrite($file_to_write, "new text".$old_text);

---

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.

---

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.

---

            $file = fopen('filepath.txt', 'r+') or die('Error');
            $txt = "/n".$string;
            fwrite($file, $txt);
            fclose($file);

This will add a blank line in the text file, so next time you write to it you replace the blank line. with a blank line and your string.

This is the only and best trick.