Execute System Commands in Java on Mac

Question

I want to be able to make run a system command on Mac OSX from within Java. My code looks like this:

public void checkDisks() throws IOException, InterruptedException {
    Process p = Runtime.getRuntime().exec("df -h");
    int exitValue = p.waitFor();
    System.out.println("Process exitValue:" + exitValue);


    BufferedReader reader = new BufferedReader(new InputStreamReader(
                                                 p.getInputStream()));
    String line = reader.readLine();
    while (line != null) {
        line = reader.readLine();
    }
    System.out.println(line);
}

This always returns null and an exitValue of 0. Never done this before in Java so any thoughts or suggestions greatly appreciated.

0 indicates normal execution of the command "df -h", but why are you trying to read the InputStream from p ? you may want to read from a file instead. — Ankit Rustagi
– Ankit Rustagi, Commented Oct 14, 2013 at 9:02

BaRoN · Accepted Answer · 2013-10-14 09:04:19Z

3

Your code is almost OK, you just misplaced the println

public void checkDisks() throws IOException, InterruptedException {
    Process p = Runtime.getRuntime().exec("df -h");
    int exitValue = p.waitFor();
    System.out.println("Process exitValue:" + exitValue);


    BufferedReader reader = new BufferedReader(new InputStreamReader(
                                                 p.getInputStream()));
    String line = reader.readLine();
    while (line != null) {
        line = reader.readLine();
        System.out.println(line);
    }
}

I believe it's what you're trying to achieve.

answered Oct 14, 2013 at 9:04

BaRoN

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1 Comment

BaRoN Over a year ago

That'll do for testing purposes. When using in production, I'd advise using StringBuilder.

user2511414 · Accepted Answer · 2013-10-14 09:09:22Z

1

try this

public void checkDisks() throws IOException, InterruptedException {
    Process p = Runtime.getRuntime().exec(new String[]{"df","-h"});
    int exitValue = p.waitFor();
    BufferedReader reader = new BufferedReader(new InputStreamReader(
                                                 p.getInputStream()));
    String line;
    while ((line=reader.readLine()) != null) {
            System.out.println(line);
    }
    System.out.println("Process exitValue:" + exitValue);
}

answered Oct 14, 2013 at 9:09

user2511414

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