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From: konsolebox <konsolebox@gmail.com>
Newsgroups: gnu.bash.bug
Subject: Re: An array variable created by export/readonly builtins inside a function becomes a locale variable to that function unexpectedly
Date: Mon, 30 Nov 2015 22:22:52 +0800
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Approved: bug-bash@gnu.org
Message-ID: <mailman.1010.1448893376.31583.bug-bash@gnu.org>
References: <70266BC6-C65A-4D95-B7C1-2F63F3C45DEF@qq.com> <20151130132909.GH27325@eeg.ccf.org>
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Cc: ziyunfei <446240525@qq.com>, bug-bash <bug-bash@gnu.org>
To: Greg Wooledge <wooledg@eeg.ccf.org>
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On Mon, Nov 30, 2015 at 9:29 PM, Greg Wooledge <wooledg@eeg.ccf.org> wrote:
> On Sat, Nov 28, 2015 at 11:18:24AM +0800, ziyunfei wrote:
>> $ bash -c 'foo() { readonly a=(1);echo a=$a; }; foo; echo a=$a' # a becomes a local variable
>> a=1
>> a=
>
> "readonly" is a synonym for "declare -r", and declare (without the -g
> option) always marks variables as local when used in a function.

That's also how I used to think about it, but I'm not sure when it has
been official.  No part of the documentation seems to tell that
`readonly` acts similar to `declare`, `typeset` and `local`.

Also a variable seems to be only made local when it is defined as an
array variable.

$ bash -c 'a=0; foo() { readonly a=(1); echo a=$a; }; foo; a=2; echo a=$a'
a=1
a=2
$ bash -c 'a=0; foo() { readonly a=1; echo a=$a; }; foo; a=2; echo a=$a'
a=1
bash: a: readonly variable