Re: Colored prompt + cmdline ending at right margin => no explicit newline

[Chet Ramey]

On 11/18/17 3:45 PM, Egmont Koblinger wrote:

> Bash Version: 4.4
> Patch Level: 12
> Release Status: release
> 
> Hi,
> 
> Type a command (such as "echo asdfgh....") that just reaches the right edge
> of the terminal (the cursor wraps to the next line) and execute it.
> 
> Then, do any of these:
>  - double click on the last word of the command, or the first word of its
> output,
>  - copy-paste across this line boundary to a graphical text editor,
>  - resize the terminal horizontally if it supports rewrap-on-resize (such
> as gnome-terminal or urxvt).
> 
> With a simple prompt such as PS1='\u@\h $ ' the result is as expected:
>  - double-click highlighting stops at that line boundary,
>  - copy-pasting reveals that there's an explicit newline there,
>  - rewrap on resize does what's expected.
> 
> Running 'script' reveals that the cursor is actually moved up, then to the
> right by 79 columns, the last letter of the command is repainted and an
> explicit newline is added.
> 
> Let's do the same with a colored prompt, e.g. PS1='\[\e[33m\]\u@\h
> $\[\e[m\] '
>  - double clicking selects across the line boundary,
>  - copy-pasting doesn't insert an explicit linebreak,
>  - rewrap on resize does silly things.
> 
> According to 'script', the cursor is moved upwards and then immediately a
> newline is printed to move it back. This, at least in some popular/standard
> terminal emulators I've tried now (xterm, urxvt, gnome-terminal) does not
> cause that line to be terminated with a hard newline.
> 
> Could bash (readline?) please perform the "magic" of reprinting the last
> character followed by an explicit newline, even in case of more complex
> prompts?

Yes. Thanks for the report and the reproducible test case. This happens in
_rl_update_final(), which needs to be updated to deal with a prompt
containing invisible characters in this special case.

Chet

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://cnswww.cns.cwru.edu/~chet/