Interfacing with linux

Question

Hi,
How can I use my java application as a front end to run the linux commands. For eg : if I click a button on my java application it should run the command "adduser john" or "passwd john". Also how can I intercept the result of these commands. I would appreciate the help.

Answer 1

By using java.lang.Runtime
For useradd
you would write something like
String account = "john";
Process adduser = Runtime.getRuntime().exec("useradd " + account);
InputStream addUserIn;
byte[] bytes;
int read;
// wait until the process has terminated
adduser.waitFor();
if ( adduser.getExitValue() != 0 )
   // create an error message
   // read the message from std out of the adduser process.
   addUserIn = adduser.getOutputStream();
   bytes = new byte[256];
   while ( (read = addUnserIn.read( bytes )) >= 0 )
      // Write the message to the console
      // or something else like a message box.
      System.out.write( bytes, 0, read);
}The example also shows you how to interact with the external process - via StdIn,StrErr and StdOut.
If you want to run the external commands interactively it's a more complicated
you'll have to parse the Strings from the InputStream and write your response to the OutputStream of the process.