How to toggle between vim buffer and command shell screen in vim?

Question

I find it annoying to constantly press Ctrl-Z and then fg to go between these screens (where command terminal is the command line that you used to invoke vim from). It also generates unwanted fg lines on my console. I'm pretty sure this can be done as I remember doing it when I was in university, but I can't remember how.

Information on Terminals and its Relation to vim

vt100 terminal and others have a way to save the screen prior to changing it and then it could restore it when it wants to. vim does this and can be seen if you go into vim and then shell or Ctrl-Z out. Most of the time it will show you what you had on the screen prior to entering vim by saving the screen prior to painting the vim screen. If your terminal doesn't support this functionality, it will just put the command line directly under the vim screen, scrolling it up. This can be seen by exporting to the TERM variable a less functional terminal emulation or clearing it (though by clearing it, it may put vim into line mode or may use the most basic of terminal codes depending on its implementation). To see more on saving/restoring a screen, see Terminal codes (ANSI/VT100) introduction, under the heading Save/restore screen.

Answer 1

Starting gvim opens a new window, so the terminal window stays available for commands. For intermediate "shell escapes" I do :sh to get access to a shell session, and type <Ctrl>-D to exit it; no fg is needed, but a prompt is added in this case to the console shell. And with no X running I start two consoles, one where vim is running, and the other where the shell is running, and I switch consoles by (in my case) e.g. <Ctrl>-<Alt>-<F1>. (Depending on the actual needs, one of those options should fit; I hope.)

Answer 2

Does the Vim command :shell work as you want? :shell<return> causes Vim to run your $SHELL. When you exit the shell, you're back in Vim, right where you left off.

Answer 3

Ok, so I've figured out how I can do this with Gary Johnson's help on the Google Groups vim_use group. He helped by stating how to run the tput commands from vim. Here is my final solution:

1. Have the following function script in vim memory:

   function! ShowTerm()
       call system(">/dev/tty tput rmcup")
       call input("")
       call system(">/dev/tty tput smcup")
       redraw!
   endfunction
   

2. Map the script to some command key sequence like this:

   map [= :call ShowTerm()<CR>
   

I used the sequence [=, but you can use whatever you want.

Now type the key sequence and you get the other screen. Press Enter and you're back to the vim screen. The Enter doesn't add a line feed to the terminal screen either, so no marching lines.

Nice! :) Note that this probably isn't the way it was done 15-20 years ago, but it works.

EDIT

In order not to be dependent on tput being available, I've found that the following that @MarkPlotnick inferred works just as well. Just replace the function ShowTerm() above with:

function! ShowTerm()
    silent !read -sN 1
    redraw!
endfunction

This depends on bash being used as the shell (or others that have a similar read call).

2nd Edit

Further, you can have this automated by putting a .vim file into your ~/.vim/plugins folder that contains the following:

" Function that allows viewing command line display last time it was seen.
" Note: Will only work on terminals that allow saving/restoring the display.
function! ShowTerm()
    " This will invoke the command shell and call the read function.
    " Will exit when a key is pressed.  This is specific to bash and
    " and may have to be changed if using a different shell.
    silent !read -sN 1
    redraw!
endfunction

" Maps [= sequence to view command line display last time it was seen.
map [= :call ShowTerm()<CR>