mysqldump via PHP

Question

I have a PHP script that gets passed the MySQL connection details of a remote server and I want it to execute a mysqldump command. To do this I'm using the php exec() function:

<?php
exec("/usr/bin/mysqldump -u mysql-user -h 123.145.167.189 -pmysql-pass database_name > /path-to-export/file.sql", $output);
?>

When the right login details are passed to it, it'll work absolutely fine. However, I'm having trouble checking if it executes as expected and if it doesn't finding out why not. The $output array returns as empty, whereas if I run the command directly on the command line a message is printed out telling me the login failed. I want to capture such error messages and display them. Any ideas on how to do that?

Answer 1

You should check the third parameter of exec function: &$return_var.

$return_var = NULL;
$output = NULL;
$command = "/usr/bin/mysqldump -u mysql-user -h 123.145.167.189 -pmysql-pass database_name > /path-to-export/file.sql";
exec($command, $output, $return_var);

By convention in Unix a process returns anything other than 0 when something goes wrong.

And so you can:

if($return_var) { /* there was an error code: $return_var, see the $output */ }