java run bash script, command not found

Question

I tried to use java to run some bash script and store the terminal output in a string. However, there are a lot of commands don't work in this way. It keeps showing command not found, but I can run those commands correctly in terminal, ex node --version, go --version. I guess is the path issue, but have no idea how to fix it.

Another question, when I run "python --version", it shows "Python 2.7.10" but it is in getErrorStream. Can anyone give me some hint?

public static void runscript() throws IOException {
    Runtime rt = Runtime.getRuntime();
    String[] commands = { "/bin/bash", "-c", "node --version" };
    Process proc = null;
    try {
        proc = rt.exec(commands);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    BufferedReader stdInput = new BufferedReader(new InputStreamReader(proc.getInputStream()));

    BufferedReader stdError = new BufferedReader(new InputStreamReader(proc.getErrorStream()));

    // read the output from the command
    System.out.println("Here is the standard output of the command:\n");
    String s = null;
    while ((s = stdInput.readLine()) != null) {
        System.out.println(s);
    }

    // read any errors from the attempted command
    System.out.println("Here is the standard error of the command (if any):\n");
    while ((s = stdError.readLine()) != null) {
        System.out.println(s);
    }
}

Answer 1

Reply @VishalKamat comment.
when I tried using the output of "which node" as my path, which is "/usr/local/bin/node". It works!!!
But, does that mean I have to change the path when I need to get different application version info? I thought I can easily get the info just like I do in terminal.

I try to print $PATH by java in this way

String[] commands = { "/bin/bash","-c", "$PATH" };

The error msg is :

/bin/bash: /usr/bin:/bin:/usr/sbin:/sbin: No such file or directory