PHP中exec（）的输出为空数组

Question

I have the following code to execute mysqldump using exec() . It was not working and I wanted figure out what output the command line throws. So I printed $output and $worked . But all I get is 1 and an empty array .

Accordong to manual: If the output argument is present, then the specified array will be filled with every line of output from the command. But why is this throwing an empty array? I am including 2>&1 at the end of command as some post suggested, but still not working. I want to know what the terminal is outputting when this command is being executed.

And what does $worked outputting 1 mean?

Any help will be greatly appreciated!

Script:

$command='mysqldump --opt -u ' .$db['username'] .' -p' .$db['password'] .' --databases ' .$db['database'] .' > '.$mysqlExportPath .' 2>&1';
$output=array();
exec($command,$output,$worked);

print $worked.'<br>';
print_r($output);

Outputs:

1
Array ( ) 

Answer 1

I want to know what the terminal is outputting when this command is being executed.

Nothing ! (And had you simply tried it yourself you'd have seen that immediately). Your command directs the result of mysqldump to the file at the path denoted by $mysqlExportPath . I don't know why you expect it to go to stdout instead.

Perhaps some line breaks would help to make your code a little (no, substantially !) more readable:

$command
  = 'mysqldump --opt'
  . ' -u ' . $db['username']
  . ' -p' . $db['password']
  . ' --databases ' . $db['database']
  . ' > ' . $mysqlExportPath   // <---- Here you go!
  . ' 2>&1';

Remove the redirection, or find the data inside the file $mysqlExportPath ; your call!