Typing "b main<RET>" in the *gud* buffer results in the following error
message:

> Current buffer has no process

On Fri, Aug 11, 2017 at 12:52 PM, Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Itai Berli <itai.berli@gmail.com>
> > Date: Fri, 11 Aug 2017 12:27:01 +0300
> > Cc: Emacs developers <emacs-devel@gnu.org>
> >
> > Paul Eggert wrote:
> >
> > > type the GDB command "b Fexpand_file_name" to plant a breakpoint in
> (say) Fexpand_file_name
> >
> > What do you mean by 'Fexpand_file_name'? The name of a file, or the name
> of a function?
>
> It's the name of a function.
>
> > Could you give me
> > a concrete example? Suppose, for instance, I wish to place a breakpoint
> at the start of the 'main; function. How
> > can I do so?
>
> "b main".  "b" is a short for "break".
>