Re: PS0 vs. \[ \] followup

Chet Ramey <[email protected]> Wed, 10 Jun 2026 12:15:51 -0400

Newsgroups	gmane.comp.shells.bash.bugs
Organization	ITS, Case Western Reserve University
Message-ID	<[email protected]>

On 6/9/26 3:40 PM, Robert Elz wrote:

>    | $ PS4='+\[$\]-'
>    | $ set -x
>    | $ echo hello
>    | +$- echo hello
>    | hello
> 
> If that's what you're trying to achieve, then
> 
> 	PS4='+\$-'
> 
> will do it, and what's more, work the same way in PSn (for any n), and
> whether or not line editing is enabled.

Not quite, since \$ is a valid prompt expansion escape sequence, but you
can make it work.

> As I understand the bash rules, between the \[ and \] in prompts there
> are only supposed to be data which affects the display mode of the
> terminal (change colour, bold, blinking, ...) and do not cause any
> actual visible output.   If you have a '$' there (alone) then that breaks
> the rules, and I think anything is reasonable as a result.

This is true, even if the documentation is not quite explicit that these
sequences are not useful in any other context.

Chet
-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
		 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    [email protected]    http://tiswww.cwru.edu/~chet/

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