How to run NPM Command in Java using Process Builder

Question

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import         


        

Answer 1

The problem is that ProcessBuilder does not respect the PATHEXT variable on Windows.

It's true there is no npm binary on Windows, there's a npm.cmd. My best solution is to check the platform. Something like this:

static boolean isWindows() {
    return System.getProperty("os.name").toLowerCase().contains("win");
}

static String npm = isWindows() ? "npm.cmd" : "npm";

static void run() {
    Process process = new ProcessBuilder(npm, "update")
            .directory(navigatePath)
            .start()
}

Answer 2

In Unix or Linux os , the PathBuilder takes the default environment path , so we have to change the environment path and run the npm command through the bash.

    package com.ainosoft.space.manager.command.executor;
    import java.io.File;
    import java.util.Map;

    public class CommandExecutor {
    public void exceuteCommand(String commandString,String 
    directoryToExecuteCommand) {
    try {
        ProcessBuilder processBuilder = new ProcessBuilder(new String{"bash", "-c",commandString});
        Map<String, String> env = processBuilder.environment();
        processBuilder.directory(new File(directoryToExecuteCommand));
        String envPath="/home/admin123/.nvm/versions/node/v10.15.3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin";
        env.put("PATH",envPath);
        processBuilder.start();
     } catch (Exception e) {
        e.printStackTrace();
   }

  }
public static void main(String args[]) {
    CommandExecutor commandExecutor=new CommandExecutor();
    commandExecutor.exceuteCommand("npm install", "/home/admin123/Desktop");
}

}