Using the “alternate screen” in a bash script

问题

The alternate screen is used by many "user-interactive" terminal applications like vim, htop, screen, alsamixer, less, ... It is like a different buffer of the terminal content, which disappears when the application exits, so the whole terminal gets restored and it looks like the application hasn't output anything.

I'd like to achieve exactly the same thing in my own shell (bash) script, except that it doesn't have to be that portable. I'd stick to linux only and xterm-based terminal emulators; but the solution should use something like tput if it's possible. However, I don't want to use some external scripting language (or even something like C).

Although I don't want to use C (as it should be a bash-script with as few dependencies as possible), I had a look into the source code of less. It seems to use terminfo as the database and looks up the "ti" terminal capability in its initialisation. When removing the line, it doesn't use the alternate sceen, so I assumed that I found the responsible code line.

However, I can't find such a capability in man terminfo. But maybe I'm on the wrong path finding a solution for this. Maybe terminfo / tput isn't my friend.

So (how) can I use the alternate screen in a bash script? Does somebody know a simple application in which source code I may find a hint? (C application or bash script or whatever...)

回答1:

You can switch to the alternate screen using this command:

$ tput smcup

And back with:

$ tput rmcup

These commands just output the appropriate escape sequences for your terminal. If it is an XTERM they will be equivalent to the (more known but less elegant or portable):

$ echo -e "\e[?1049h"

And:

$ echo -e "\e[?1049l"

For more terminal control commands see man 5 terminfo.

回答2:

smcup/rmcup are used, but only for the side effect: the escape sequence which switches between normal/alternate screens is usually embedded in those terminfo capabilities -- not always.

Some background is in the xterm faq Why doesn't the screen clear when running vi?

回答3:

For C console application:

ncurses

Wikipedia:

ncurses (new curses) is a programming library that provides an API which allows the programmer to write text-based user interfaces in a terminal-independent manner.

less uses this library.

A hello world program from here, to compile it in gcc, flag -lncurses is needed.

#include <ncurses.h>

int main()
{   
    initscr();          /* Start curses mode          */
    printw("Hello World !!!");  /* Print Hello World          */
    refresh();          /* Print it on to the real screen */
    getch();            /* Wait for user input */
    endwin();           /* End curses mode        */

    return 0;
}

来源：https://stackoverflow.com/questions/11023929/using-the-alternate-screen-in-a-bash-script

标签

Linux

bash

terminal

terminfo