php : Capturing the command output

Question

Hi All,

I am using exec function to execute the specific executable files in php .

exec ( $file , $output , $return_value  ) ;

When the given file executed successfully I am able to get the output in the second argument by checking the return values , So, It is working fine. But My requirement is when the command execution getting failed due to some reason. I need to get that error message of that executed program . What I need to do to get the error . through second argument we can get the successful output only . Not error message.

Thanks.

Answer 1

The $return_value will have the error code returned by the program which should be meaningfull enough, I don't think you can have better.

Answer 2

The second argument $output only captures STOUT from your executable. Error messages are usually sent to STERR so that they easily can be written to an error log or similar, but this means that you won't see them when you call exec.

If this is a linux system, you could append 2>&1 to your command, in order to redirect STERR to STOUT. I haven't tried this, but it should forward the error messages to your $output variable.

Edit:

I've read up on it on www.php.net/exec, and it seems this would work.

exec($file.' 2>&1', $outputAndErrors, $return_value);

It is also possible to redirect the errors to a temporary file and read them separatly.

exec($file.' 2> '.$tmpFile, $outputOnly, $return_value);

Edit 2

It seems windows also uses this Bourne style output redirecting syntax, so the examples should work for windows too.

More on input and output streams

Answer 3

try output buffetring

ob_start();
exec ( $file , $output , $return_value  ) ;
$content = ob_get_contents();