code: public static boolean chmod(final String as, final File f, final int permissions)
  	{
  		if (!f.exists())
  		{
  			log.error("[FileHelper] {chmod} Non-existant file: " + f.getPath());
  			return false;
  		}
  
  		try
  		{
  			Execed call = Exec.utilityAs(as, "chmod", Integer.toOctalString(permissions), f.getPath());
  
  			int returnCode = call.waitForExit();
  			return returnCode == 0;
  		}
  		catch (Exception e)
  		{
  			log.error("[FileHelper] {chmod} Failure: " + e.getMessage(), e);
  			return false;
  		}
  	}
docs: Performs a chmod (which assumes this system is Linux/UNIX/Solaris/etc), replacing the permissions using octal
  
  @param f
  @param permissions
  <strong>REMEMBER TO SPECIFY THIS VALUE IN OCTAL (ie. with a leading zero)</strong>
  
  @return
  
  @throws IOException