Android run bash command in app

Question

Hi i'm developing an application which requires me to run some bash code is there a way i can hard code the script into my app and then run it? For instance (this is a VERY simplified example)

#!/system/bin/sh
#

if [ ! -f /sdcard/hello.txt ]
then
echo 'Hello World' >> /sdcard/hello.txt
else
echo 'Goodbye World' >> /sdcard/goodbye.txt
fi

I have the following method for running one line bash commands but need to run something like that that's on multiple lines. Again that above code is a very simplified example what I am actually doing must be run through a script and can't be done through java. I also want to have it hard coded I know could have the script stored on the phone and run it with the following but do not want the script just out there would rather it hard coded in the app.

public Boolean execCommand(String command) 
    {
        try {
            Runtime rt = Runtime.getRuntime();
            Process process = rt.exec("su");
            DataOutputStream os = new DataOutputStream(process.getOutputStream()); 
            os.writeBytes(command + "\n");
            os.flush();
            os.writeBytes("exit\n");
            os.flush();
            process.waitFor();
        } catch (IOException e) {
            return false;
        } catch (InterruptedException e) {
            return false;
        }
        return true; 
    }

Thank you for any help with my issue

Answer 1

If I understand you correctly, all you have to do is change the one line example method to something which accepts and sends multiple lines, like so:

    public Boolean execCommands(String... command) {
    try {
        Runtime rt = Runtime.getRuntime();
        Process process = rt.exec("su");
        DataOutputStream os = new DataOutputStream(process.getOutputStream());

        for(int i = 0; i < command.length; i++) {
            os.writeBytes(command[i] + "\n");
            os.flush();
        }
        os.writeBytes("exit\n");
        os.flush();
        process.waitFor();
    } catch (IOException e) {
        return false;
    } catch (InterruptedException e) {
        return false;
    }
    return true; 
}

That way, you can call your multiline bash commands like so:

    String[] commands = {
            "echo 'test' >> /sdcard/test1.txt",
            "echo 'test2' >>/sdcard/test1.txt"
    };

    execCommands(commands);

    String commandText = "echo 'foo' >> /sdcard/foo.txt\necho 'bar' >> /sdcard/foo.txt";

    execCommands(commandText.split("\n"));