Php writing to file - empty?

Question

I've been struggling with writing a single string into a file. I'm using just a simple code under Slackware 13:

$fp = fopen('/my/absolute/path/data.txt', 'w');
fwrite($fp, 'just a testing string...');
fclose($fp);

The file gets created (if it's not already created) but it's empty ?! The directory in which this file is written is owned by apache's user & group (daemon.daemon) and has 0777 permissions. This has never happened to me before. I'm curious what's the reason I'm not able to write inside the file ?

Thanks in advance.

Answer 1

Try $ df -h

It probably means your disk is full.