dtach eats output of prev. commands

[safinaskar]

Type some commands to terminal. Then start dtach. Then exit from dtach. You will see all previous activity (i. e. before starting dtach) is disappeared (as opposed to screen and tmux).

$ dtach --version
dtach - version 0.9, compiled on May 21 2016 at 08:04:42.

[rdebath]

Dtach doesn't really understand the terminal emulator that you're using. It doesn't filter the output from the host at all.

Because of this the 'alternate screen' that 'screen' and 'tmux' can use to preserve the previous state of the terminal is not available; it may be used by the program that you run using dtach.

Now IF your problem is that you're running a text editor under dtach and the text editor would normally use the alternate screen but the screen is getting cleared with dtach. I may have a solution for you.

The second item in my PR #5 will let you disable this clear screen.

[ackerleytng]

@safinaskar Could the behavior you're observing be because dtach tries to send Ctrl-L after reconnecting? I believe Ctrl-L "clears" the previous commands on the shell.

Try and see if adding -r winch for dtach makes a difference. In my experience, the previous activity is not cleared away by changing the redraw method with -r.

[safinaskar]

@ackerleytng , I tried dtach -c /tmp/sock -r winch bash and I don't see any difference. (Also, I lost interest in dtach anyway, and I don't remember why I needed it in the first place, so you may close this bug.)

[safinaskar]

(I just did this dtach -c /tmp/sock -r winch bash test with dtach 0.9)

[Atry]

script can record the output, so combining dtach with script would solve the problem.

To start a session and record output:

dtach -c /tmp/my-session.dtach script --flush /tmp/my-session.typescript

To restore the output and attach to the session:

sleep 0.1 && cat /tmp/my-session.typescript & dtach -a /tmp/my-session.dtach -r none

The sleep 0.1 part is tricky. Without it, cat would print the output but then dtach would clear it. Adding sleep 0.1 lets cat be executed after starting dtach.