PHP fwrite doesn't update the file using the append mode - php

Question

The following code is working but it doesn't update the contents of the file it created.
I can see that the file contents have changed (the size increased) but when I download the file from my server it's empty.
the file is chmod to 666 and its parent directory as well.
its a linux server running Apache and PHP.
I've also tried using fflush to force it to flush the contents.
<?php
header("Location: http://www.example.com");
$handle = fopen("log.txt", "a");
foreach($_POST as $variable => $value) {
fwrite($handle, $variable);
fwrite($handle, '=');
fwrite($handle, $value);
fwrite($handle, '\r\n');
}
fwrite($handle, '\r\n');
fflush($handle);
fclose($handle);
?>
what is the problem?
Thanks!

Answer 1

I think a good practice is to check if a file is writable with is_writable then if it can be opened by checking the value returned by fopen, by the way your code is right.
Try this:
$filename = "log.txt";
$mode = "a";
// Let's make sure the file exists and is writable first.
if (is_writable($filename)) {
// In our example we're opening $filename in append mode.
// The file pointer is at the bottom of the file hence
// that's where $somecontent will go when we fwrite() it.
if (!$handle = fopen($filename, $mode)) {
echo "Cannot open file ($filename)";
exit;
}
foreach($_POST as $variable => $value) {
fwrite($handle, $variable);
fwrite($handle, '=');
fwrite($handle, $value);
fwrite($handle, '\r\n');
}
fwrite($handle, '\r\n');
fflush($handle);
fclose($handle);
echo "Content written to file ($filename)";
} else {
echo "The file $filename is not writable";
}