One thing is wrong dor sure: When using single quotes (' '), as you did, the variable $output will
not be replaced with the value of $output. Use double quotes (" ") instead.
Also, what is the value of $output? Can www-data really write there?
You can Check with this: $cmd = "tide -ml -fh -o $output
2>&1"; Any errors from the 'tide' program will show in you browser.
I noticed 'tide' outputs html code. You could also try without the
-o $output part first. The html from 'tide' will show nicely in the browser.
Complete example:
PHP Code:
<html>
<head>
<title>Tides</title>
</head>
<body>
<?php
$output = '/tmp/tide.html';
$cmd = "tide -ml -fh";
// $cmd = "tide -ml -fh -o $output 2>&1";
// $cmd = "tide -ml -fh -o $output";
system($cmd);
?>
</body>
</html>
