Re: command substitution subshell exits when assigning to readonly variable

[ikhxcsz7y xmbott]

On Wed, Oct 18, 2023, 00:59 ikhxcsz7y xmbott <ikhxcsz7y@gmail.com> wrote:

> ~ $ readonly r=.
> ~ $ { r= ; } 2>/dev/null
> ~ $ { r= ; } #2>/dev/null
> bash: r: readonly variable
> ~ $
>

2>&- also works

On Wed, Oct 18, 2023, 00:39 Philippe Cerfon <philcerf@gmail.com> wrote:
>
>> Dear list.
>>
>> When I have a script like:
>> echo 1
>> V="$(
>> echo a >&2
>> false
>> echo b >&2
>> )"
>> echo 2
>>
>> I get:
>> 1
>> a
>> b
>> 2
>> when executing or sourcing it.
>>
>>
>> But when I have:
>> readonly R=.
>>
>> echo 1
>> V="$(
>> echo a >&2
>> R=
>> echo b >&2
>> )"
>> echo 2
>>
>> I get:
>> 1
>> a
>> b.sh: line 9: R: readonly variable
>> 2
>> when executing it, and something similar when sourcing it.
>>
>>
>> set -e is not used. And something like R= || true doesn't help either.
>>
>>
>> This does not seem to happen, when outside a command substitution:
>> readonly R=.
>>
>> echo 1
>> R=
>> echo 2
>>
>> gives:
>> 1
>> bash: R: readonly variable
>> 2
>> regardless of whether executed or sourced.
>>
>>
>> Also:
>> R= 2> /dev/null
>> doesn't do what one might hope it would. I assume this is because the
>> redirection happens after the assignment?
>> So the only thing one could do is exec 2> /dev/null before?
>>
>> Regards,
>> Philippe.
>>
>>