Access linux terminal to send shutdown command

Question

I'm needing to access the linux terminal to send the shutdown command,
here is the code i'm trying
  try{
            Process p = Runtime.getRuntime().exec("sudo shutdown -h now");
        }catch ( Exception e){
            System.out.println("Exception in shuttin down machine");
            JOptionPane.showMessageDialog(null,"Can't shutdown.  Shit!");
        }I've used this commend to use the command line in windows, but not sure how to change it over for linux.
Thanks

Answer 1

I had a similar problem recently where I need to send multiple commands after the initial Runtime.exec(). My solution involved a PrintWriter...
Process p = Runtime.getRuntime().exec("sudo shutdown -h now");
PrintWriter pw = new PrintWriter(p.getOutputStream());
pw.println("yourpassword");
pw.flush();
pw.close();As far as this...
"sudo (and ssh etc.) won't take password from the stdin, if it is not a terminal. "
... Im not really sure. The method above did work for me, but if sudo doesn't check stdin, Im not sure how my solution works
A couple other things you might consider. When you use Runtime.exec(), you are passing the system a command, you are not sending a string to a command line. For example, trying to run ...
Process p = Runtime.getRuntime().exec("ls /usr/bin");
... will do nothing since "ls" does not start a new process, but is more of a routine. Likewise, you may or may not have problems using the shutdown command. If you do have problems, you may need to start a terminal with Runtime.exec(), and then send the shutdown command through the terminals stdin using the PrintWriter method.
And on a second note, you may also need to reorganize your code to this...
Process p = Runtime.getRuntime().exec("sudo", "shutdown", "-h", "now");
Runtime.exec() will take your string and pass it as a command, it is not meant to directly pass arguments. It may work fine as you have it, but if you run into problems, pass your commands in as a String[] (as shown right above)
Hope that helps
Edited by: cpetzol2 on Apr 2, 2008 7:49 PM