I'm a new user of OS X, and I want to configure the shell to display prompts and command line input in distinctive colors. I've done this kind of thing in Linux, so doing it in OS X should not be a problem, but it's not working. I need assistance understanding why.

I've studied several sets of instructions for this process. All of them boil down to:

1. Create or open ~/.bash_profile.

2. Insert some commands in the file that enable terminal color display and define the colors to use. (All of the instructions provide copy-and-paste examples.)

3. Save the file.

4. Start a new terminal window and look at the pretty colors.

This has no effect on the appearance of a terminal window. I don't see any error messages or other clues to the reason.

I've tried executing the copy-and-paste commands directly in a terminal window. In that case they do affect the output, although not in expected ways. (I assume that's because some of the commands contain escape characters which have different effects in a typed command than in a script.)

I'm looking for advice on how to fix the problem, or if that's not possible at this point, how to diagnose it.