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!
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