Java ProcessBuilder examples

In Java, we can use ProcessBuilder to call external commands easily :


	ProcessBuilder processBuilder = new ProcessBuilder();

	// -- Linux --

	// Run a shell command
	processBuilder.command("bash", "-c", "ls /home/mkyong/");

	// Run a shell script
	processBuilder.command("path/to/hello.sh");

	// -- Windows --

	// Run a command
	processBuilder.command("cmd.exe", "/c", "dir C:\\Users\\mkyong");

	// Run a bat file
	processBuilder.command("C:\\Users\\mkyong\\hello.bat");

	Process process = processBuilder.start();

1. Ping

1.1 Run an external ping command to ping a website 3 times, and display the output.

ProcessBuilderExample1.java

package com.mkyong.process;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class ProcessBuilderExample1 {

    public static void main(String[] args) {

        ProcessBuilder processBuilder = new ProcessBuilder();

        // Run this on Windows, cmd, /c = terminate after this run
        processBuilder.command("cmd.exe", "/c", "ping -n 3 google.com");

        try {

            Process process = processBuilder.start();

			// blocked :(
            BufferedReader reader =
                    new BufferedReader(new InputStreamReader(process.getInputStream()));

            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }

            int exitCode = process.waitFor();
            System.out.println("\nExited with error code : " + exitCode);

        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }

}

Output


Pinging google.com [172.217.166.142] with 32 bytes of data:
Reply from 172.217.166.142: bytes=32 time=10ms TTL=55
Reply from 172.217.166.142: bytes=32 time=10ms TTL=55
Reply from 172.217.166.142: bytes=32 time=10ms TTL=55

Ping statistics for 172.217.166.142:
    Packets: Sent = 3, Received = 3, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 10ms, Maximum = 10ms, Average = 10ms

Exited with error code : 0

2. Ping + Thread

In above example 1.1, the process.getInputStream is “blocking”, it is better to start a new Thread for the reading process, so that it won’t block other tasks.

ProcessBuilderExample2.java

package com.mkyong.process;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.List;
import java.util.concurrent.*;
import java.util.stream.Collectors;

public class ProcessBuilderExample2 {

    public static void main(String[] args) {

        ExecutorService pool = Executors.newSingleThreadExecutor();

        ProcessBuilder processBuilder = new ProcessBuilder();

        // Run this on Windows, cmd, /c = terminate after this run
        processBuilder.command("cmd.exe", "/c", "ping -n 3 google.com");

        try {

            Process process = processBuilder.start();

            System.out.println("process ping...");
            ProcessReadTask task = new ProcessReadTask(process.getInputStream());
            Future<list<string>> future = pool.submit(task);

            // no block, can do other tasks here
            System.out.println("process task1...");
            System.out.println("process task2...");

            List<string> result = future.get(5, TimeUnit.SECONDS);
            for (String s : result) {
                System.out.println(s);
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            pool.shutdown();
        }
    }

    private static class ProcessReadTask implements Callable<list<string>> {

        private InputStream inputStream;

        public ProcessReadTask(InputStream inputStream) {
            this.inputStream = inputStream;
        }

        @Override
        public List<string> call() {
            return new BufferedReader(new InputStreamReader(inputStream))
				.lines()
				.collect(Collectors.toList());
        }
    }

}

Output


process ping...
process task1...
process task2...

Pinging google.com [172.217.166.142] with 32 bytes of data:
Reply from 172.217.166.142: bytes=32 time=11ms TTL=55
Reply from 172.217.166.142: bytes=32 time=10ms TTL=55
Reply from 172.217.166.142: bytes=32 time=10ms TTL=55

Ping statistics for 172.217.166.142:
    Packets: Sent = 3, Received = 3, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 10ms, Maximum = 11ms, Average = 10ms

3. Change Directory

3.1 Change to directory C:\\users and run external dir command to list out all the files.

ProcessBuilderExample3.java

package com.mkyong.process;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;

public class ProcessBuilderExample3 {

    public static void main(String[] args) {

        ProcessBuilder processBuilder = new ProcessBuilder();

        processBuilder.command("cmd.exe", "/c", "dir");
        processBuilder.directory(new File("C:\\users"));

        // can also run the java file like this
        // processBuilder.command("java", "Hello");

        try {

            Process process = processBuilder.start();

            BufferedReader reader =
                    new BufferedReader(new InputStreamReader(process.getInputStream()));

            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }

            int exitCode = process.waitFor();
            System.out.println("\nExited with error code : " + exitCode);

        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }

}

Output


 Volume in drive C has no label.
 Volume Serial Number is CE5B-B4C5

 Directory of C:\users

//...

References

  1. Microsoft System Error Codes (0-499)
  2. How to execute shell command from Java
  3. Java docs – ProcessBuilder
  4. What does cmd /C mean?

About the Author

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mkyong
Founder of Mkyong.com, love Java and open source stuff. Follow him on Twitter. If you like my tutorials, consider make a donation to these charities.

Comments

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MartyRajaram chelleduraiTodd Recent comment authors
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Marty
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Marty

In Eclipse, I get an error with the code below. Type mismatch: cannot convert from List to List

@Override
public List call() {
return new BufferedReader(new InputStreamReader(inputStream))
.lines()
.collect(Collectors.toList());
}

Rajaram chelledurai
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Rajaram chelledurai

how to run a batch file with arguments using ProcessBuilder

Todd
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Todd

Minor typo in code: <list> should be <List>