RunTime.exec() and FTP

[Judy Collins]

Hi Guys,
On WinXP, I am using
String command ="cmd /c ftp -v -s: cmd.txt "
Runtime.getRuntime().exec(command);
....
.....

FTP Command is supposed to get a file from remote server, but as long as my program is running it does not get the file. Once I kill my program all of a sudden file pops up.
But if I leave my program running file never shows up.

Any ideas, help is greatly appreciated.

[William Brogden]

It appears that you have not provided for consuming the stdout and stderr streams from the process that your exec() creates. The ftp program is probably trying to write something - since you don't read it, the program hangs.
Bill

[Stephen Huey]

In other words, you might need to do something like this:

 
        try {
            Process myProgram = java.lang.Runtime.getRuntime().exec( myCommandLineString );
            BufferedReader response = new BufferedReader(new InputStreamReader(myProgram.getInputStream()));
            String line = "";
            StringBuffer sb = new StringBuffer("");
            while ((line = response.readLine()) != null) {
                System.out.println(line);  // just let anyone watching see something happening                
            }
            response.close();      
                        
        } catch (IOException e) { 
            System.out.println("IOException when running the command line program: " + e);            
        }        

It's like milking a cow. She's all pent-up, wanting that release, and if you don't draw it out of her, she can get quite ornery and not behave the way you'd like!

Ok, that's my first and maybe last ranch analogy here at JavaRanch...

[William Brogden]

To continue Stephans analogy - his code only pulls on one teat - the stdout stream. If the program also write to std err, you need to write a separate Thread to suck on that teat too. - ewww
Bill

[Judy Collins]

Thank you guys!