Re: Shouldn't readonly (-r) prevent type changes?

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On Sat, Jul 25, 2026 at 6:11=E2=80=AFPM Oliver Kiddle <[email protected]> wrote:

> I think ksh treats all variables as being arrays so thatisn't a type
> conversion. It was already a one element array.
>

That's equally true in bash and ksh - you can treat scalar parameters as
1-element arrays, and likewise treating an array as a scalar parameter will
get you its first element. But that doesn't extend to the type flags;
there's a visible difference between a var that has been explicitly
declared as an array (either by assignment or typeset/declare) and one that
hasn't.

And it's not quite as a simple as ksh lets you change it and bash doesn't.
I was able to get ksh to toggle the array type of a readonly parameter
once, but I haven't been able to reproduce that result since. It doesn't
raise an error, but the type is not changed. Whereas bash always raises an
error.

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Mark J. Reed <[email protected]>

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<div dir=3D"ltr"><div dir=3D"ltr"><span style=3D"background-color:transpare=
nt">On Sat, Jul 25, 2026 at 6:11=E2=80=AFPM Oliver Kiddle &lt;<a href=3D"ma=
ilto:[email protected]">[email protected]</a>&gt; wrote:</span></div><div class=3D"gmai=
l_quote gmail_quote_container"><blockquote class=3D"gmail_quote" style=3D"m=
argin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left=
:1ex">I think ksh treats all variables as being arrays so thatisn&#39;t a t=
ype<br>
conversion. It was already a one element array.<br></blockquote><div><br></=
div><div>That&#39;s equally true in bash and ksh - you can treat scalar par=
ameters as 1-element arrays, and likewise treating an array as a scalar par=
ameter=C2=A0will get you its first element. But that doesn&#39;t extend to =
the type flags; there&#39;s a visible difference between a var that has bee=
n explicitly declared as an array (either by assignment or typeset/declare)=
 and one that hasn&#39;t.=C2=A0</div><div><br></div><div>And it&#39;s not q=
uite as a simple as ksh lets you change it and bash doesn&#39;t. I was able=
 to get ksh to toggle the array type of a readonly parameter once, but I ha=
ven&#39;t been able to reproduce that result since. It doesn&#39;t raise an=
 error, but the type is not changed. Whereas bash always raises an error.</=
div><div><br></div><div>--</div></div><div dir=3D"ltr" class=3D"gmail_signa=
ture">Mark J. Reed &lt;<a href=3D"mailto:[email protected]" target=3D"_bl=
ank">[email protected]</a>&gt;<br></div></div>

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