Question

Can anyone tell the method to modify/delete the contents of a text file using PHP

Answer 1

By using fopen:

if (is_writable($filename)) {
  if (!$handle = fopen($filename, 'w')) {
     echo "Cannot open file ($filename)";
     exit;
  }
  if (fwrite($handle, $somecontent) === FALSE) {
    echo "Cannot write to file ($filename)";
    exit;
  }

  echo "Success, wrote to file ($filename)";

  fclose($handle);
}

Write “” to a file to delete its contents.

To delete contents line by line use:

$arr = file($fileName);

unset($arr[3]); // 3 is an arbitrary line

then write the file contents. Or are you referring to memory mapped files?