Accessing Unix-commands via JNI

Question

Hello everyone,
I'm currently developing for an Solaris - SPARC - environment a java application, which is processing a huge amount of files without out GUI.
As there are some limitations the Java-File - Object gives me in respect of the desired platform-independency of java, I'm right now looking for a way of using Unix - commands like "ln" or "ls" via JNI. I have no problem with accessing this commands vie the Runtime.exec(command) - construct. But the overhead which it leads to, because every time a new Unix-Process ist forked to execute the command, is not acceptable for me.
I see a slight chance of using JNI, but I can't figure out, how to acces the Unix-Calls, I'd like to execute. Could anyone give me a hint.
Thank You a lot.
Thomas

Answer 1

I have no problem with accessing this
commands vie the Runtime.exec(command) - construct.
But the overhead which it leads to, because every time
a new Unix-Process ist forked to execute the command,
is not acceptable for me.Just create a background shell process that you feed commands when you need to.
This example should get you started.import java.io.*;
class PipeSh {
    private Process sh;
    private OutputStream shIn;
    private BufferedReader shOut;
    private BufferedReader shErr;
    PipeSh() {
        try {
            sh = Runtime.getRuntime().exec("sh");
            shIn = sh.getOutputStream();
            shOut = new BufferedReader(new InputStreamReader(sh.getInputStream()));
            shErr = new BufferedReader(new InputStreamReader(sh.getErrorStream()));
        } catch (IOException ex) { ex.printStackTrace(); }
    void execute(String cmd) {
        try {
            shIn.write(cmd.getBytes());
            shIn.flush();
            while (shOut.ready()) System.out.println(shOut.readLine());
            while (shErr.ready()) System.out.println(shErr.readLine());
        } catch (IOException ex) { ex.printStackTrace(); }
    private static String[] cmd = { "mkdir foo\n", "cd foo\n", "touch bar\n" };
    public static void main(String[] arg) {
        PipeSh ps = new PipeSh();
        for (int i=0;i<cmd.length;++i) ps.execute(cmd);