Why does this not work?

Question

Hi All,
Take the following test code:
      1 import java.io.*;
      2
      3 public class GetFsSpace {
      4
      5     private String[] cmd = {"df"};
      6
      7     public static void main(String[] args) {
      8         GetFsSpace fs = new GetFsSpace();
      9         fs.runCmd();
     10     }
     11
     12     public void runCmd() {
     13
     14         try {
     15             Runtime rt = Runtime.getRuntime();
     16             Process proc = rt.exec(cmd);
     17             InputStream stdout = proc.getInputStream();
     18             InputStreamReader isr = new InputStreamReader(stdout);
     19             BufferedReader br = new BufferedReader(isr);
     20             String line = null;
     21             System.out.println("<Starting output.>");
     22
     23             while ( (line = br.readLine()) != null) {
     24                 System.out.println(line);
     25             }
     26
     27         } catch (Throwable t) {
     28             t.printStackTrace();
     29         }
     30     }
     31 }Now, this compiles and works fine, however, if I change the String in line 5 to read:
private String[] cmd = {"df -k"};It throws an exception. So it's obviously to do with the string and I'm probably missing the obvious here, but can someone point me in the right direction?
many thanks
Doug.

Answer 1

appologies, here's the exception I get when I run it:
java -cp . GetFsSpace
java.io.IOException: java.io.IOException: df -k: not found
        at java.lang.UNIXProcess.<init>(Unknown Source)
        at java.lang.ProcessImpl.start(Unknown Source)
        at java.lang.ProcessBuilder.start(Unknown Source)
        at java.lang.Runtime.exec(Unknown Source)
        at java.lang.Runtime.exec(Unknown Source)
        at GetFsSpace.runCmd(GetFsSpace.java:16)
        at GetFsSpace.main(GetFsSpace.java:9)and this only happens when I add the "-k" option to df.
thanks.