Re: Get cursor position (Was: [bug report] prompt can erase messages written on the terminal by background processes)

[Stephane Chazelas <stephane@chazelas.org>]

2022-12-08 10:02:15 +0000, Stephane Chazelas:
[...]
> (bash does by exploiting some bug (calling unset -v in a
> severate function peels one layer of scoping instead of
> unsetting in the current scope)).
[...]

Not sure how "separate" became "severate" there. Sometimes it
feels like my fingers have a life of their own... Sorry.

unlocal in bash (or yash) can be written:

unlocal() { unset -v "$@"; }

(that's one of the main reasons POSIX couldn't specify "local"
btw).

It's worse in mksh where unset is always unlocal.

$ bash -c 'unlocal() { unset -v "$@"; }; f() { local a=1; g; echo "f: $a"; }; g() { local a=2; unlocal a; echo "g: $a"; a=3; }; a=0; f'
g: 1
f: 3
$ yash -c 'unlocal() { unset -v "$@"; }; f() { local a=1; g; echo "f: $a"; }; g() { local a=2; unlocal a; echo "g: $a"; a=3; }; a=0; f'
g: 1
f: 3

$ zsh -c 'unlocal() { unset -v "$@"; }; f() { local a=1; g; echo "f: $a"; }; g() { local a=2; unlocal a; echo "g: $a"; a=3; }; a=0; f'
g:
f: 1
$ dash -c 'unlocal() { unset -v "$@"; }; f() { local a=1; g; echo "f: $a"; }; g() { local a=2; unlocal a; echo "g: $a"; a=3; }; a=0; f'
g:
f: 1
$ bosh -c 'unlocal() { unset -v "$@"; }; f() { local a=1; g; echo "f: $a"; }; g() { local a=2; unlocal a; echo "g: $a"; a=3; }; a=0; f'
g:
f: 1

-- 
Stephane