How can I get the process ID using Java for Linux Ubuntu?

Question

Firstly, I ran the sample.jar with "java -jar sample.jar" command in bash.

Then trying to execute the "ps -ef | grep "sample.jar"" command in Linux with Java and to get the process ID on which the sample.jar is running.

String cmd = "ps -ef | grep \"sample.jar\"";
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec(cmd);

But by the following code I couldn't find the process ID:

BufferedReader stdInput = new BufferedReader(new 
InputStreamReader(proc.getInputStream()));
String s = null;
if ((s = stdInput.readLine()) != null) {
    String str[] = s.split("\\s+", 3);
    String processId = str[1]; // I need this processId
    rt.exec("kill " + processId);
}

I want to find the process id and kill the process. So that I can re-run my spring boot project on the same port.

Answer 1

Instead of using kill , you can use the proc.destroy() or the proc.forciblyDestroy() methods, which does effectively the same thing and has the added bonus of being cross platform!