Re: endwin, and temporarily leaving curses mode

[Thomas Dickey]

On Fri, 21 Apr 2006, Mike Mueller wrote:

> I'm working on a program which spends all its time in
> curses/raw/noecho mode.  Recently I started working on a feature that
> lets users drop out to a shell temporarily.  This seems to be a common
> thing to do, and the answer in the docs is endwin() before the shell,
> and refresh() after, as seen here:
>
> http://www.roseindia.net/linux/tutorial/linux-howto/NCURSES-Programming-HOWTO/misc.html#TEMPLEAVE
>
> However, I run endwin(), then invoke the shell (via system()) and the
> result is somewhat correct, but not completely.  The shell displays a
> normal prompt, but typed characters are not echoed back to the
> terminal.  'ls' displays things in neat columns, so it seems like

I don't see this (checking with ncurses' test program - menu 'a', 's' to 
shell-out).

> we're in a semi-cooked mode.  Finally, when the user exits the shell,
> I prompt "press enter to continue" and call fgets() to wait for that
> 'enter' before anything else happens.  Unfortunately, hitting enter
> (or ^M) doesn't do anything at this prompt.  Hitting ^J, on the other
> hand, does work.
>
> When I call refresh(), curses is back to normal and my app is working
> fine.  So the problem is only in the endwin-shell part of the process.

That part is expected behavior: refresh() checks to see if there was an 
endwin() which reset the terminal modes.  I don't recall(*) a bug in this
area - but it is possible to confuse things by saving the ncurses terminal 
modes as the default, e.g.,

       The def_prog_mode and def_shell_mode routines save the current terminal
       modes as the "program" (in curses) or "shell" (not in curses) state for
       use by the reset_prog_mode and reset_shell_mode routines.  This is done
       automatically  by initscr.  There is one such save area for each screen
       context allocated by newterm().

(*) but if I knew the version of ncurses and the platform, something might
    come to mind.

--
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net