how to retrieve the value of ps - A command

[baran tamer]

Hello , i am trying to get the pid of a process which i know is unique

My code below is not working for "ps - A | grep vlc" , however it works for "ifconfig"

String commandToBeExecuted = "ps -A | grep  vlc";
        try {
            String line;
            Process p = Runtime.getRuntime().exec(commandToBeExecuted);
            BufferedReader input =new BufferedReader(new InputStreamReader(p.getInputStream()));

            while ((line = input.readLine()) != null) {
                output+=line;
            }
        }
        catch (Exception err) {
            err.printStackTrace();
        }

output returns null . Any ideas ?

[Dmitry Mamonov]

Is it works with only:
String commandToBeExecuted = "ps -A";
?

[Dmitry Mamonov]

   
		String commandToBeExecuted = "more.com _out2.txt | more.com";
		try {
			String line;
			Process p = Runtime.getRuntime().exec(commandToBeExecuted);
			BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));

			while ((line = input.readLine()) != null) {
				System.out.println("line: "+line);
			}
		} catch (Exception err) {
			err.printStackTrace();
		}

Code above works fine. May be grep command eliminates all rows?

[Martijn Verburg]

Hi there,

As an extra, have a read of the Javaworld article "Why Runtime.exec() won't", it's a very important set of guidelines when dealing with this sort of thing.

[Rob Spoor]

"ps - A | grep vlc" is not one command - it's two commands, with the output of the first used as input for the second.