How to execute shell command in Java?

Question

I was thinking if I could send a shell to execute Client-Server ipconfig. Is that possible?

This is my code in Local:

class Comando {
    public static void main(String args[]) {

        String s = null;

        try {

            // Determinar en qué SO estamos
            String so = System.getProperty("os.name");
            String comando;
            // Comando para Linux
            if (so.equals("Linux"))
                comando = "ifconfig";
            // Comando para Windows
            else
                comando = "ipconfig";

            // Ejcutamos el comando
            Process p = Runtime.getRuntime().exec(comando);

            BufferedReader stdInput = new BufferedReader(new InputStreamReader(
                    p.getInputStream()));

            BufferedReader stdError = new BufferedReader(new InputStreamReader(
                    p.getErrorStream()));

            // Leemos la salida del comando
            System.out.println("Ésta es la salida standard del comando:\n");
            while ((s = stdInput.readLine()) != null) {
                System.out.println(s);
            }

            // Leemos los errores si los hubiera
            System.out
                    .println("Ésta es la salida standard de error del comando (si la hay):\n");
            while ((s = stdError.readLine()) != null) {
                System.out.println(s);
            }

            System.exit(0);
        } catch (IOException e) {
            System.out.println("Excepción: ");
            e.printStackTrace();
            System.exit(-1);
        }
    }
}

Thank You in Advance!

OneCricketeer · Accepted Answer · 2022-07-17 16:16:27Z

15

I am not sure if you are asking about Shell command execution, or ipconfig in general.

If the first is the case here: Yep, you can use Runtime.getRuntime.exec(). Related Answers (In Stackoverflow):

Moreover to the answers provided there, here is my example on how you do it with "host -t a" command for DNS lookups. I would generally recommend to read through the list you get and append them in an String for logging purposes.

p = Runtime.getRuntime().exec("host -t a " + domain);
p.waitFor();
     
BufferedReader reader = 
  new BufferedReader(new InputStreamReader(p.getInputStream()));
     
String line = "";           
while ((line = reader.readLine())!= null) {
    sb.append(line + "\n");
}

The other solution which herausuggested was to use ProcessBuilderand execute the command from there. For this you need to use Java SE 7 upwards. Here is an example that starts a process with a modified working directory and environment, and redirects standard output and error to be appended to a log file:

 ProcessBuilder pb =
   new ProcessBuilder("myCommand", "myArg1", "myArg2");
 Map<String, String> env = pb.environment();
 env.put("VAR1", "myValue");
 env.remove("OTHERVAR");
 env.put("VAR2", env.get("VAR1") + "suffix");
 pb.directory(new File("myDir"));
 File log = new File("log");
 pb.redirectErrorStream(true);
 pb.redirectOutput(Redirect.appendTo(log));
 Process p = pb.start();
 assert pb.redirectInput() == Redirect.PIPE;
 assert pb.redirectOutput().file() == log;
 assert p.getInputStream().read() == -1;

If you wanna know more about ProcessBuilder, read through the documentation: Oracle Documentation on Class ProcessBuilder

edited Jul 17, 2022 at 16:16

OneCricketeer

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answered Apr 27, 2014 at 11:25

Amir Rahnama

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4 Comments

Funereal Over a year ago

But I have to create another .java for the server with this code?

Amir Rahnama Over a year ago

Well yes, for the best practice: put codes which are related in their own chunks. Create a Util.java for example and put it there or be more specific and say ShellUtil.java and make a general function that you can invoke any shell command there.

herau Over a year ago

Before JDK 5.0, only way is to use the exec() method of the java.lang.Runtime class. After JDK 5.0, you can executing a command in a separate process, through a class called ProcessBuilder

Amir Rahnama Over a year ago

thanks herau, I did not know about ProcessBuilder but you are right. I updated my answer with Process Builder Option as well.

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