How to execute " cat foo | grep something " in java

Question

Hi guys ...
Am trying to execute " cat foo | grep dude " , where foo is a text file which contains a lot of texts and words. I tried a lot of choices but I end up with nothing like -
Process p = Runtime.getRuntime().exec(new String[] {"cat", "foo"}); , and by creating a stream reader on the process I get the content of foo file , but I want to grep something and I tried , Process p = Runtime.getRuntime().exec(new String[] {"cat", "anas","| grep Dude"}); but I got the same result from the above command , I tried a lot of possibilities like -
(new String[] {"cat", "anas","|", "grep", "Dude"});
(new String[] {"cat anas | ","grep Dude"});
and so on , also I tried to put the command in a string and execute it like here
String command = "cat" + " foo" + " |" + " grep Dude" ;
Process p = Runtime.getRuntime().exec(command);
.. I don't know it's like work fine but when it reached the part that related to " grep something" it just ignore it . so can someone help me in this .thanks for reading and thanks in advance for any further help ... by the way this the content of the foo file
Dude I Am here
what !! you cant
see me or you
pretend to be blind !!

Answer 1

if cat and grep are executable programs that work outside of the console app, it should work. But I don't think this is the case, in which case you need to open a console first.
I haven't tried this on Unix, but below is how to do it on Windows. If you wanted to run "more" or "less" or "cd" etc in on dos, you need to open the console first.
          String cmd = "cmd.exe";
          TextAreaOutputStream taos = new TextAreaOutputStream(this);
          try {
               mDOS = Runtime.getRuntime().exec(cmd);
               Piper p = new Piper (mDOS.getInputStream(), taos);
               new Thread(p).start();
               p = new Piper (mDOS.getErrorStream(), taos);
               new Thread(p).start();
               mDosOut = new PrintStream(mDOS.getOutputStream());
          catch (IOException iox) {
               iox.printStackTrace();
          }