Re: history expansion

--000000000000d08fea0656bee0a0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Bash tries to be a little cleverer about not invoking history expansion
when it's not intended:

bash-5.3$ echo "foo!"
foo!


But it still does do history expansion inside double-quotes:

bash-5.3$ echo "foo!!"
echo "fooecho "foo!""
fooecho foo!


So that first command is technically ambiguous; the *!"* *could* mean
"include the entire previous history line that begins with a double-quote".

bash-5.3$ "ls"
foo
bash-5.3$ !"
"ls"
foo


Although that doesn't seem to work at all in zsh for some reason:

zsh% "ls"
foo
zsh% !"
zsh%


On Wed, Jul 15, 2026 at 7:03=E2=80=AFPM Vincent Lefevre <[email protected]=
> wrote:

> On 2026-07-14 13:06:17 -0700, Bart Schaefer wrote:
> > On Tue, Jul 14, 2026 at 3:42=E2=80=AFAM Vincent Lefevre <vincent@vinc17=
.net>
> wrote:
> > > My problem was more with things like
> > >
> > >   echo "foo!"
> >
> > You probably know this: history expansion takes place inside "..." but
> > not inside '...'.
>
> Perhaps I should have asked whether anyone relies on history expansion
> inside double quotes (it is supported by bash, but differently, e.g.
> no history expansion with the above command in bash).
>
> --
> Vincent Lef=C3=A8vre <[email protected]> - Web: <https://www.vinc17.net/=
>
> 100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
> Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon)
>
>

--=20
Mark J. Reed <[email protected]>

--000000000000d08fea0656bee0a0
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">Bash tries to be a little cleverer about not invoking hist=
ory expansion when it&#39;s not intended:<div><br></div><blockquote style=
=3D"margin:0 0 0 40px;border:none;padding:0px"><div><font face=3D"monospace=
">bash-5.3$ echo &quot;foo!&quot;</font></div><div><font face=3D"monospace"=
>foo!</font></div></blockquote><div><div><br></div><div>But it still does d=
o history expansion inside double-quotes:</div><div><br></div></div><blockq=
uote style=3D"margin:0 0 0 40px;border:none;padding:0px"><div><div><font fa=
ce=3D"monospace">bash-5.3$ echo &quot;foo!!&quot;</font></div></div><div><d=
iv><font face=3D"monospace">echo &quot;fooecho &quot;foo!&quot;&quot;</font=
></div></div><div><div><font face=3D"monospace">fooecho foo!</font></div></=
div></blockquote><div><div><br></div></div><div>So that first command is te=
chnically ambiguous; the <b>!&quot;</b>=C2=A0<i>could</i> mean &quot;includ=
e the entire previous history line that begins with a double-quote&quot;.</=
div><div><br></div><blockquote style=3D"margin:0 0 0 40px;border:none;paddi=
ng:0px"><div><font face=3D"monospace">bash-5.3$ &quot;ls&quot;</font></div>=
<div><font face=3D"monospace">foo</font></div><div><font face=3D"monospace"=
>bash-5.3$ !&quot;</font></div><div><font face=3D"monospace">&quot;ls&quot;=
</font></div><div><font face=3D"monospace">foo</font></div></blockquote><di=
v><br></div><div>Although that doesn&#39;t seem to work at all in zsh for s=
ome reason:</div><div><br></div><blockquote style=3D"margin:0 0 0 40px;bord=
er:none;padding:0px"><div><font face=3D"monospace">zsh% &quot;ls&quot;</fon=
t></div><div><font face=3D"monospace">foo</font></div><div><font face=3D"mo=
nospace">zsh% !&quot;</font></div><div><font face=3D"monospace">zsh%</font>=
</div></blockquote></div><br><div class=3D"gmail_quote gmail_quote_containe=
r"><div dir=3D"ltr" class=3D"gmail_attr">On Wed, Jul 15, 2026 at 7:03=E2=80=
=AFPM Vincent Lefevre &lt;<a href=3D"mailto:[email protected]">vincent@vin=
c17.net</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"=
margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-lef=
t:1ex">On 2026-07-14 13:06:17 -0700, Bart Schaefer wrote:<br>
&gt; On Tue, Jul 14, 2026 at 3:42=E2=80=AFAM Vincent Lefevre &lt;<a href=3D=
"mailto:[email protected]" target=3D"_blank">[email protected]</a>&gt; wr=
ote:<br>
&gt; &gt; My problem was more with things like<br>
&gt; &gt;<br>
&gt; &gt;=C2=A0 =C2=A0echo &quot;foo!&quot;<br>
&gt; <br>
&gt; You probably know this: history expansion takes place inside &quot;...=
&quot; but<br>
&gt; not inside &#39;...&#39;.<br>
<br>
Perhaps I should have asked whether anyone relies on history expansion<br>
inside double quotes (it is supported by bash, but differently, e.g.<br>
no history expansion with the above command in bash).<br>
<br>
-- <br>
Vincent Lef=C3=A8vre &lt;<a href=3D"mailto:[email protected]" target=3D"_b=
lank">[email protected]</a>&gt; - Web: &lt;<a href=3D"https://www.vinc17.n=
et/" rel=3D"noreferrer" target=3D"_blank">https://www.vinc17.net/</a>&gt;<b=
r>
100% accessible validated (X)HTML - Blog: &lt;<a href=3D"https://www.vinc17=
.net/blog/" rel=3D"noreferrer" target=3D"_blank">https://www.vinc17.net/blo=
g/</a>&gt;<br>
Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon)<br=
>
<br>
</blockquote></div><div><br clear=3D"all"></div><div><br></div><span class=
=3D"gmail_signature_prefix">-- </span><br><div dir=3D"ltr" class=3D"gmail_s=
ignature">Mark J. Reed &lt;<a href=3D"mailto:[email protected]" target=3D=
"_blank">[email protected]</a>&gt;<br></div>

--000000000000d08fea0656bee0a0--