Since you appear to be new here, I'd like to mention that the way to get the quickest responses is to actually cut and paste your commands and their responses from your terminal.

"xyz is not working" or "xyz does not do anything" are very vague statements; somewhat like calling your car mechanic and telling him "my car won't start". There could be a lot of reasons for that and the mechanic won't know what's wrong with your car unless he actually inspects it himself. It's the same thing over here.

In any case, here are the steps to install Cygwin from what I could remember; see if you followed them all.

(1) You have a working (non-corrupted) version of Windows and you downloaded setup.exe from the Cygwin website.
(2) If your computer is 32-bit, you downloaded the 32-bit version of setup.exe, or ditto for 64-bit.
(3) You double-clicked on setup.exe and clicked through the wizard to install Cygwin. In the final screen, it shows you an option to put up an icon on your Windows desktop. If you had checked that, you'd see the Cygwin icon on your desktop.
(4) Assuming that you do see the icon; if you double-click on it, the Cygwin shell would've opened up. By default, it is the Bash shell, and you'd see a "prompt". If you keep on pressing the "Enter" or "Return" key, you'd see the prompt printed repeatedly, because it is waiting for you to enter a command.
(5) Now, "ls" and "cat" are pretty basic commands, so they should be installed as a part of the core setup. If you've done everything till now as mentioned above, then run the following commands at your prompt:

Code:

type ls

and then

Code:

type cat

They should provide you some information about what "ls" and "cat" are in your system. Run those commands and paste their output over here.

(6) The "ls" command without any argument lists all the files (which includes directories in Unix/Linux) in the current directory. So if you are in an empty directory, "ls" won't print anything and you'll simply see your prompt printed in the next line. Maybe that's what you are confused about?
Try the following command:

Code:

ls -al

This will print a long listing of all files, including hidden files, which in Unix/Linux are the ones that start with "." character. You should see atleast two lines printed. Post the output of this command over here.

(7) The "cat" command "concatenates" the contents of the files you pass as arguments.
- If you pass one argument, it will print the contents of that file.
- If you pass two arguments, it will print the contents of the two files one after the other. Ditto with more than two arguments.
- If you don't pass any arguments and press "Enter", it will simply wait for you to enter something. Once you enter something, it will simply echo your input.
Maybe that's what you saw?

Try this command:

Code:

cat myfile

If a file called "myfile" exists in your current directory, this command will print its contents. If it does not, it will show an appropriate error message. Cut and paste the output of that command over here.

Without knowing:
(a) what that program is
(b) what language it is written in
(c) how it was saved or compiled in your system
(d) how it was invoked by you
(e) how you passed the arguments to it

it is difficult to say why it came up with NULLs.

Let's say you saved your program in a file called "myfile". Then run the following command:

Code:

cat myfile

and paste its output over here.
And then copy and paste the command(s) you ran to invoke it and the response you received.