How to set a shortcut to run make in Vim and show the output

Question

I'd like to run make and display the output when I press Ctrl+m in Vim. I know how to run make and display the output while in command mode, thanks to this StackOverflow answer, namely with:

:make | copen

but how do I bind this to a keyboard shortcut? I managed this when I was just running make and not displaying the output namely with:

noremap <C-m> :make<CR>

in my ~/.vimrc file. Unfortunately, adding | copen after :make and before <CR> results in this Vim start up error:

Error detected while processing /home/fusion809/.vimrc:
line  157:
E488: Trailing characters:  copen <CR>
Press ENTER or type command to continue

Answer 1

When you want to map to a key sequence that contains | you have to be careful. See :help map_bar.

You should probably use this mapping:

noremap <C-m> :make<BAR>copen<CR>

Answer 2

<Ctrl-M> is equivalent to <CR>

First of all, please note that <Ctrl-M> is equivalent to <CR> which you might not use in normal mode and therefore is ok for you. If you use the mapping, you can also press <CR> in normal mode to trigger make.

If you like to use a different mapping, have a look at the plugin

vim-dispatch by Tim Pope

This plugin provides following mappings

• menter :Make<CR>
• mspace :Make<Space> (enter arguments)
• m!+enter :Make!
• m? Show 'makeprg'

and the new command :Make works as follows

                                                *dispatch-:Make*
:Make [arguments]       Using the current |:compiler| settings, dispatch a
                        build in the foreground.  Adapter strategies vary, but
                        the goal is visibility without stealing focus.  When
                        the build is complete, load the results into the
                        |quickfix| list and call |:cwindow|.  This command is
                        preferred for shorter tasks like "build this file."

:Make! [arguments]      Using the current compiler settings, dispatch a build
                        in the background.  Use |:Copen| to load the results.
                        This command is preferred for longer tasks like "run
                        the entire test suite."

Note the difference between :copen and :cwindow:

                            *:cw* *:cwindow*
:cw[indow] [height] Open the quickfix window when there are recognized
            errors.  If the window is already open and there are
            no recognized errors, close the window.

                        *:cope* *:copen* *w:quickfix_title*
:cope[n] [height]   Open a window to show the current list of errors.