screen: how to turn on alternate screen?

Question

When I work in terminal, I see the history of the last shell commands execution output. If I run vim, I see the file I open full screen. When I exit vim, I can see the history of the last shell commands again.

However, when I use vim from screen. I see the footprint of the file I was just editing on my exit from vim instead of the history of the last shell commands. I'd like to see the shell's history though.

How can I achieve this behaviour?

I used:

• terminal.app and iterm2.app
• tried switching xterm to xterm-256color (in iterm2.app)
• checking and unchecking "Save lines to scrollback when an app status bar is present" and "Save lines to scrollback in alternate screen mode" (in iterm2)
• adding termcapinfo xterm ti@:te@ to .screenrc (although it should be a solution to the opposite problem, but why not to try)
• sshing to linux machines and trying to use gnu-screen there

Up to now I didn't get the desired behaviour.

P.S.

I googled a bit and saw comments of people who try to solve the opposite problem:

Many of you probably know the annoying behaviour of console-based programs like less or vi restoring the screen after exiting so that the text you just had there vanishes.

The main idea behind this behaviour is whether programs use alternate screen to save a picture of the shell history and show it when vim exits. Thus if one wants to solve the opposite problem, he should

exorce the evil alternate screen

Answer 1

UPDATE : I had forgotten about a feature of screen that disables alternate screen support by default.

Add altscreen on to your $HOME/.screenrc to enable it. This is probably all you have to do; all the messing about with $TERM, $TERMCAP, and $TERMINFO is probably unnecessary. I'll leave the rest of this answer here anyway.

I've had this in my own .screenrc so long it slipped my mind.

To enable this feature for the current session, type your screen escape character (Cntrl-A by default) followed by :altscreen on Enter.

Without this, screen won't respond to the escape sequences, even if they're defined in terminfo or termcap.

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vim (and less, and most other curses-based full-screen programs) use the smcup and rmcup strings defined by the terminfo entry for your terminal. (These are referred to as ti and te, respectively, in the older termcap system). smcup switches to the alternate screen, and rmcup switches back to the primary screen.

If your terminfo entry doesn't have these strings, programs won't be able to do that.

The screen command, by default, sets your $TERM to "screen". Apparently the "screen" terminfo entry doesn't have smcup and rmcup.

If you feel like hacking terminfo entries, you can modify your existing information for "screen" to add smcup and rmcup. You'll need the infocmp command to convert your terminfo to a text, and tic to convert it back to the binary form used by terminfo.

A simpler solution is to set your $TERM environment variable to whatever it was before you invoked the screen command. Almost all terminal emulators these days are based on the old DEC VT100, so they should be sufficiently compatible.

On my system, for example, when I login I have TERM=xterm; it's likely something else on MacOS. Within a screen session, by default, I'd have:

 $ echo $TERM
 screen

I could change it to xterm like this:

$ export TERM=xterm

(Again, replace "xterm" by whatever $TERM is on your system.)

You can also add

term xterm

to your $HOME/.screenrc. In fact screen has a number of options for tweaking your termcap/terminfo settings; man screen and search for "terminfo" for the gory details.