bug#41558: Regexp Bug

[Norihiro Tanaka]

On Tue, 26 May 2020 21:14:12 -0700
"anton.paras" <anton@paras.nu> wrote:

> I posted to Stack Exchange, and they recommended that I file a bug. I'd 
> rather not copy+paste it all, so here's the link:
> 
> 
> 
> https://unix.stackexchange.com/questions/579889/why-doesnt-this-sed-command-replace-the-3rd-to-last-and
> 
> 
> 
> here's an example
> 
> 
> 
> > echo 'dog and foo and bar and baz land good' |??? sed -E 
> > 's/(.*)\band\b((.*\band\b){2})/\1XYZ\2/'
> 
> 
> 
> expected output:?dog XYZ foo and bar and baz land good
> 
> actual output:?dog and foo XYZ bar and baz land good
> 
> 
> here's my sed --version output:?sed (GNU sed) 4.2.2
> 
> 
> 
> I hope this is helpful, cheers!

$ echo 'foo and bar land' | env LC_ALL=en_US.utf8 sed -nE '/(.*\band){2}/p'
foo and bar land
$ echo 'foo and bar land' | env LC_ALL=en_US.utf8 sed -nE '/.*\band.*\band/p'
$

It seems that there is the bug in regex.

expected:
$ echo 'foo and bar land' | env LC_ALL=en_US.utf8 sed -nE '/(.*\band){2}/p'
$ echo 'foo and bar land' | env LC_ALL=en_US.utf8 sed -nE '/.*\band.*\band/p'
$

It also reproduces in grep.

$ echo 'foo and bar land' | env LC_ALL=en_US.utf8 grep -E '(.*\band){2}'
foo and bar land
$ echo 'foo and bar land' | env LC_ALL=en_US.utf8 grep -E '.*\band.*\band'
$