fopen creates the file, so why is the fwrite failing? - php

Question

I have this stupid little test PHP script running on a Ubuntu system inside an instance of a virtual server (Oracle Virtual Box) running on my pc:
<?
error_reporting(E_ALL);
ini_set('display_errors', 1); // show errors
echo "<p>test</p>";
$filename = "andy.txt";
$fh = fopen($filename, 'w') or die('fopen failed');
fwrite($fh, "qwerty") or die('fwrite failed');
fclose($fh);
?>
Despite all appropriate directory and file permissions being set, it is failing on the fwrite. The fopen works and creates the file, so write access is clearly enabled, but the fwrite dies, and the 'fwrite failed' message is output (no other error output is displayed).
The same script works perfectly well when I upload to my real server, so I am completely stumped as to why it won't write to the file; maybe it's something about my virtual server that is causing the problem.
Seems like such a pathetic thing, but it's driving me nuts! Considerable time Googling has failed to yield an answer, so can anybody here please provide some insight? Many thanks.

Answer 1

Not sure why the fwrite() call would die, as it returns the number of bytes written.
That said, have you tried with file_put_contents() instead? It's a simpler way of writing to a file, and is the recommended way since early PHP 5.
With it you only need to do the following
$filename = "andy.txt";
if(!file_put_contents ($contents, $filename)) {
// Write failed!
}
No need to bother with opening and closing the file pointer, as that's automatically handled by the function. :)

Answer 2

Solved! It was a disk space error on my virtual server. At the back of my mind, I knew I had seen this mentioned elsewhere as an issue with write fails, but in this case I failed to make the connection.
#ChristianF Thanks! Switching to file_put_contents() was very helpful, since it also failed, but gave me a meaningful error message:
'file_put_contents(): Only 0 of 6 bytes written, possibly out of free disk space'
Aha! Having recalled that growing log files can be a problem, I took it upon myself to delete everything inside /var/log (after saving them) and Presto! it now works! So, thank you for that tip - I will switch to using file_put_contents from now on. BTW: The contents of error.log itself was 2GB, while the remaining size of everything else in /var/log was only about 15MB, but deleting error.log by itself did not work, so I deleted everything.
#Clayton Smith Thank you, but removing the "or die('fwrite failed')" part did not result in any further error info - which is what is so frustrating: It's a shame that those error reporting directives at the start of the script didn't seem to do much.
#NaeiKinDus Thank you, but I don't think I have SELinux running (I'm afraid I don't know anything about this). Although I have a /etc/selinux directory present, there's no config file in it, just what appears to be a skeleton semanage.conf - whatever that is. Commands such as sestatus are not recognised.