Invoking Bash from Java Interactively

Invoking bash from Java interactively

OK, here' the deal.

As Eric pointed out, prompt is displayed only if input is coming from a terminal, so I needed a pseudo terminal to fool the bash script. I managed to do it by using JPty library.

How to run interactive bash using Java ProcessBuilder API?

This worked well

ProcessBuilder processBuilder = new ProcessBuilder();
        try {
            processBuilder.command("stty", "echo");
            processBuilder.inheritIO();
            processBuilder.start().waitFor(1000, TimeUnit.MILLISECONDS);
            processBuilder.command("bash", "-i");
            processBuilder.redirectErrorStream(true);
            processBuilder.inheritIO();
            processBuilder.start().waitFor();
            processBuilder.command("stty", "-echo");
            processBuilder.inheritIO();
            processBuilder.start().waitFor(1000, TimeUnit.MILLISECONDS);
        } catch (Exception e) {
            consumer.accept("exception occurred while starting bash");
            consumer.accept(e.getMessage());
        }

using which I was able to see what I was typing, but I don't know why it works. if anyone has a better answer please do post it.

run interactive command line application from java

According to the documentation you should be able to redirect the input and output streams. This tells it to use the System.in/System.out from the parent process:

builder.redirectInput(ProcessBuilder.Redirect.INHERIT);
builder.redirectOutput(ProcessBuilder.Redirect.INHERIT);

If you want to write things to the processes's input:

If the source is Redirect.PIPE (the initial value), then the standard input of a subprocess can be written to using the output stream returned by Process.getOutputStream(). If the source is set to any other value, then Process.getOutputStream() will return a null output stream.

Running an interactive shellscript using java

Read the process output stream and check for the input prompt, if you know the input prompt, then put the values to process inupt stream.
Otherwise you have no way to check.

ProcessBuilder pb = new ProcessBuilder(command);
pb.redirectErrorStream(true);
BufferedReader b1 = new BufferedReader(new InputStreamReader(p.getInputStream()));
BufferedWriter w1 = new BufferedWriter(new OutputStreamWriter(p.getOutputStream()));
String line = "";
String outp = "";
while ((line = b1.readLine()) != null) {
  if (line.equals("PLEASE INPUT THE VALUE:")) {
     // output to stream
     w1.write("42");
  }
  outp += line + "\n";
}

...

UPD: for your code it should be something like that

    ProcessBuilder pb2=new ProcessBuilder("/home/ahijeet/sample1.sh","--ip="+formobj.getUpFile().getFileName(),"--seqs="+seqs);

    script_exec = pb2.start();

            OutputStream in = script_exec.getOutputStream();

            InputStreamReader rd=new InputStreamReader(script_exec.getInputStream());   

            pb2.redirectError();

            BufferedReader reader1 =new BufferedReader(new InputStreamReader(script_exec.getInputStream()));

            StringBuffer out=new StringBuffer();

            String output_line = "";    

              while ((output_line = reader1.readLine())!= null) 
              {
                       out=out.append(output_line+"/n");
                       System.out.println("val of output_line"+output_line);

                       //---> i need code here to check that whether script is prompting for taking input ,so i can pass it values using output stream
                       if (output_line.equals("PLEASE INPUT THE VALUE:")) {
                           // output to stream
                           in.write("42");
                       }

              }

How to launch an interactive command line interface program from Java?

You can try this instead:

String[] commands = { "gnome-terminal", "-x", "-c", "./My_C_Program" };
theProcess = Runtime.getRuntime().exec(commands);

Not sure will it work. Didn't try it.

Maybe you don't have gnome-terminal but something else like x-term. It should be almost the same.

bash interactive script pass input

If you want to redirect the normal standard input of the program, you could use so called "here documents" (see e.g. the BASH manual page):

java -jar script.jar <<EOF
your input here
EOF

That means standard input (a.k.a. stdin) is redirected and will be the text in the "here document", in this case your input here.

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