GetRuntime().exec("chmod 777 a file.txt") - does not do the intended task

Question

Hi,
I am trying to change the permissions of file (file name has spaces) using the Runtime.getRuntime().exec() method on AIX platform. My sample code is -
import java.io.*;
public class ChangeMode
     public static void main(String[] args)
          Process p = null;
     String cmd = null;
          cmd = "chmod " + "000" + " " + "a file.txt";
          try
          p = Runtime.getRuntime().exec( cmd );
          p.waitFor();
          catch( Exception e )
          e.printStackTrace();
          System.out.println("The exit value "+p.exitValue());
In this case - I am getting exitValue of 2.
But, the strange part is that - I am able to run the command
"chmod 000 a file.txt "
from the command prompt successfully.
Any ideas what does an exitValue of 2 means and where is this program getting failed.
Thanks!
~Saurabh

Answer 1

Is 'a file.txt' the file name ?
If I'm right, the Runtime.exec(String cmd) method will split the given string (using spaces.)
The first token will be used a the command and the other ones as the arguments.
In your example it will call chmod with three arguments: 000, a and file.txt
In order to avoid that, you should either use the Runtime.exec(String[] cmd) method with: String[] cmd = new String[] {"chmod", "000", "a file.txt"};or try to put your file between ticks: String cmd = "chmod 000 'a file.txt'";You could have a look at this article to learn more about Runtime.exec() :
http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html
I hope it will help.