Run System Command from Java Program

In this tutorial, we will discuss how to run a system command from a Java program.

If you want to check list of processes on your system and you are an Unix user, you will definitely use ps -ef command. In the following program, we will run the command from Java program.

package com.t4b.test; import java.io.*; public class JavaRunCommand { public static void main(String args[]) { String s = null; try { Process p = Runtime.getRuntime().exec("ps -ef"); BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream())); BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream())); System.out.println("Output of the command:\n"); while ((s = stdInput.readLine()) != null) { System.out.println(s); } System.out.println("Standard error of the command (if any):\n"); while ((s = stdError.readLine()) != null) { System.out.println(s); } System.exit(0); } catch (IOException e) { System.out.println("exception"); e.printStackTrace(); System.exit(-1); } } }

Retrieve System Information

To retrieve system information you may try the following code.

package com.t4b.test; import java.lang.management.ManagementFactory; import java.lang.management.RuntimeMXBean; import java.util.Map; import java.util.Set; public class SystemInfo { public static void main(String[] args) { RuntimeMXBean runtimeBean = ManagementFactory.getRuntimeMXBean(); Map<String, String> systemProperties = runtimeBean .getSystemProperties(); Set<String> keys = systemProperties.keySet(); for (String key : keys) { String value = systemProperties.get(key); System.out.printf("[%s] = %s.\n", key, value); } } }

Check IP Address

If you want to check IP address of your local machine try the following code.

package com.t4b.test; import java.net.InetAddress; class IPAddress { public static void main(String args[]) throws Exception { System.out.println(InetAddress.getLocalHost()); } }

Open Notepad

If you want to open an applicatication using Java program, you may try the following.

package com.t4b.test; import java.util.*; import java.io.*; class Notepad { public static void main(String[] args) { Runtime rs = Runtime.getRuntime(); try { rs.exec("notepad"); } catch (IOException e) { System.out.println(e); } } }

Now, you may think that why are we going to write a complex code, where we can directly run those commands on terminal?

Here, the answer is: sometimes a program needs to be executed by some other program whithout human intervension. Thus this technique is used to automate the system.

Happy Exploring!