vi copy/paste - maybe a bit OT

[Bill Cole]

On 4 Jul 2019, at 5:32, Christoph Kukulies wrote:

> I’m asking it here although the vi in macOS surely isn’t a macport 
> but I’m asking anyway:
>
> Whenever I copy/paste a file content in vi (started from a Terminal) 
> using CMD-A or select-CMD-C to select all to put it elsewhere into a 
> text receiving object (like Notes) using CMD-V, I’m getting the 
> whole history of that terminal window. Not only the file contents.
>
> That’s confusing once you forget about that fact. You paste the 
> contents, e.g. a certificate, into a webbrowser and later you are 
> wondering about all that stuff in thet text widget which you didn’t 
> intend to get there.
>
> I understand why it might be correct that CMD-A copies the whole 
> terminal window contents, not only the vi-part, but it’s weird 
> anyway.
>
> Is the a way to circumvent this problem?

In short: No.

At length:

Terminal.app (or any equivalent tool) operates through a tightly-defined 
set of ancient interfaces to the OS: the termios line discipline and 
layers on top of that like ptmx, terminfo, and (n)curses. Terminal.app 
talks to programs like vi, bash, etc. through a full-duplex asynchronous 
serial stream of bytes. Terminal manages its data as the stream of 
characters it has drawn into its window, and it has no knowledge of what 
program it is talking to on the other side of the terminal emulation 
layers. Terminal doesn't know that you're running vi, it just knows what 
to send to the pty## device associated with a window based on your 
typing or pasting of text and how to draw characters into the window 
based on the stream of bytes it gets from that same pseudo-terminal. It 
does not know (or have any way of knowing) that you are running a text 
file editor on the other end of that pseudo-terminal link. There is no 
mechanism in the terminal emulation layers for a terminal emulator to 
communicate that sort of information or to request a logical "all data" 
of a program on the other end that may have a file-based concept of its 
current data set. Terminal only knows about the interpreted and rendered 
data in its window and scrollback buffer. One the other end, vi knows 
nothing about the system clipboard. As a practical matter, MacOS has 
always used the Mac-only Command key to construct menu equivalents for 
GUI programs, so there's no standard way to translate "Cmd-A" or any 
other "Cmd-*" combination into a stream of bytes on a pseudo-terminal 
device based on a 1980s concept of physical terminals.

In principle, a terminal emulation program like Terminal *could* have a 
command to select everything visible in a window in addition to or 
instead of a command to select the entire scrollback. I don't use it, so 
I am not certain exactly it offers, but I know that iTerm provides a 
more complex set of selection behaviors from the keyboard.

Finally, if all you want is to access the MacOS clipboard from the 
command line, pbcopy and pbpaste exist. As you might guess, pbcopy does 
a "Edit->Copy" from its stdin, pbpaste does a "Edit->Paste" to its 
stdout.

-- 
Bill Cole
bill at scconsult.com or billcole at apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire