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From: | L A Walsh |
Subject: | Re: bash doesn't display user-typed characters; can interfere with COPY/PASTE |
Date: | Wed, 09 Dec 2020 12:53:31 -0800 |
User-agent: | Thunderbird |
On 2020/12/08 06:07, Chet Ramey wrote:
On 12/7/20 8:02 PM, L A Walsh wrote:The problem is that bash isn't displaying a 'tab' character whereone was typed.It's readline and redisplay. Readline expands tabs to spaces using an internal tab stop of 8. This allows it to be sure of the physical cursor location, especially when you're doing things like wrapping lines, and insulates it from varying terminal behavior.
*snark* That's nice, why not just display 'X' instead of spaces? Wouldn'tthat also insulate readline from varying terminal behavior? *not really, but...*
I'm not sure it is the place of a an in-line-editor to override terminal features.
However, as readline is an editor and most editors allow setting the tabs (as well as whether or not to use hard-tabs or expand them). If readline has to "insulate",
just like vi/vim -- have the tabstop and whether to expand be in a startupfile like .inputrc. Right now, .inputrc has the facility to define how characters are to be interpreted. Why not put the option to expand w/spaces in there, as well as what a tab character expands (or maps to). Bash also overrides existing standards with regards to tabs wrapping. It seems that many or most terminals (xterm compat, linux console-compat, etc) don't wrap to the next line when a tab is pressed. The reasoning for that was that tab was supposed to skip to the next field in the same line. Wrapping is beyond the scope of function
for tabbing.
---- It was meant to illustrate that terminals are using the binary representation of the characters typed -- and that arbitrarily changing the binary representationWith many (most?) terminal windows these days, especially Unicode-enabled ones, the terminal has to read what is on the screen to be able to read the binary code of whatever is displayed on the screen, Otherwise, it wouldn't be able to read typed unicode.This is not relevant to the issue.
(like tabs->spaces) will mess up / corrupt the user's output stream.
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