[RESOLVED] Pass Variable as Response to Linux Prompt

rsmith

I am trying to pass a variable set by a user in one of my scripts as the answer to a prompt generated by a linux program run through exec(). I can initiate the linux program successfully by using exec("/path/to/linux/command") but as soon as this is run a prompt is generated that requires a user to type in data. I tried to pass the variable by running another exec("$variable") and even exec("echo $variable") but neither work. The prompt remains on the screen.

Any ideas? I've been Googling for hours with no luck... is it even possible?

Thanks in advance.

bradgrafelman

What you need to do is capture the STDIN handle of the newly-launched process so that you can write to it from PHP.

To do that, look into using [man]proc_open/man in place of exec(); the output of the program will be over the STDOUT handle, and the console input it normally expects will come from the STDIN handle.

rsmith

This'll be new for me; thanks for the input and direction.

rsmith

So I'm looking at the php.net manual page for proc_open and have tried to fit my scenario into it. Here's what I have:

<?php
	// Set the variable for the pw
		$var= "test";

$descriptorspec = array(
	0 => array("pipe","r"),
	1 => array("pipe","w"),
	2 => array("file","./error.log","a")
);

// define current working directory where files would be stored
	$cwd = "./";
// open process
	$process = proc_open("/path/to/program", $descriptorspec, $pipes, $cwd);

if(is_resource($process)){

  // anatomy of $pipes: 0 => stdin, 1 => stdout, 2 => error log
  	fwrite($pipes[0], "echo $var");
  	fwrite($pipes[0], "echo $var");
  	fclose($pipes[0]);

  // print pipe output
  	echo stream_get_contents($pipes[1]);

  // close pipe
  	fclose($pipes[1]);

  // all pipes must be closed before calling proc_close. 
  // proc_close() to avoid deadlock
  	proc_close($process);
}
?>

The prompt that the program generates is to set a password. So the prompt from a terminal is "Enter Password". Instead of writing to the pipes, the php script hangs and must be terminated. The error.log file is created and the prompt "Enter Password" is output to it.

rsmith

Can anyone help narrow down what might be wrong with it? Been fiddling now since I woke up 6 hours ago and no luck.

bradgrafelman

One problem I see is that you're writing:

echo testecho test

to the STDIN pipe, whereas I'm guessing that should instead be:

test
test

(without the word 'echo' and with two line breaks - one to end each input).

rsmith

So like this?

      // anatomy of $pipes: 0 => stdin, 1 => stdout, 2 => error log 
          fwrite($pipes[0], "$var \n\n"); 
          fwrite($pipes[0], "$var \n\n"); 
          fclose($pipes[0]);

bradgrafelman

Now you've got a space after "test" as well as two line breaks after each input. That would be similar to pressing the Enter/Return key twice after typing in your password each time (which probably isn't what you want).

rsmith

Ah so

"$var\n"

On each line?