Issue with Bash RegEx Handling

[Keith Thompson]

On Sun, Jul 5, 2026 at 6:14 PM Keith Thompson
<Keith.S.Thompson@gmail.com> wrote:
>
> Hans-Bernhard Bröker wrote:
> > Am 05.07.2026 um 05:18 schrieb Keith Thompson via Cygwin:
> > >>> Firstly, why is =~ completely undocumented in the bash man page?  This
> > >>> question was my first encounter with the feature.
> > >> ·
> > >> Because it's not --- not undocumented, that is.  Manpage search can't
> > >> seem to find it, but it _is_ there.
> > >> ·
> > >> Just search for '==' instead, then go one paragraph down.
> > > Searches in man pages are controlled by your pager ($PAGER or
> > > $MANPAGER).  Your pager might be treating the ~ character specially.
> > > Try searching for \~= .
> >·
> > It doesn't appear to be the pager --- it's groff translating the ~ to·
> > some other character.  One which I don't know how to type into the·
> > search pattern.
> >·
> > What does help for me is overriding the language spec:
> >·
> >      $ LC_ALL=C man bash
> >·
> > and, voila, / finds =~ just fine.
> >·
> > And FWIW, 'info bash' doesn't have that problem, either.
>
> You're right, I should have realized that.  groff 1.23.0 changed
> the way '-', '~', and '^' characters are rendered.  This affects
> a *lot* of man pages.
>
> ASCII '-' (U+002D, HYPHEN-MINUS) is translated to
> '‐' (U+2010, HYPHEN).
>
> ASCII '~' (U+007E, TILDE) is translated to
> '˜' (U+02DC, SMALL TILDE).
>
> ASCII '^' (U+005E, CIRCUMFLEX ACCENT) is translated to
> '‐' (U+02C6, MODIFIER LETTER CIRCUMFLEX ACCENT).
>
> Hyphens have been the biggest problem.  Searching a man page for
> an option name often fails because of this.

Cygwin currently has bash 5.2.21-1.

bash 5.3 updates the "bash.1" man page, and fixes the problem
with '~' and '^' characters.  (All versions render '-' characters
correctly.)

-- Keith Thompson