[U-Boot] [BUG] cmd : Local Hush Variable Could not be deleted

[U-Boot] [BUG] cmd : Local Hush Variable Could not be deleted

[Adarsh Babu Kalepalli]

Hi,

+ u-boot version:2019.10
+ H/W Board : Beaglebone Black

With 'localvar=' at the shell prompt
, I tried to delete a existing Hush-shell local variable.


-----------------------------------------------------
=> localvar=hello
=> showvar
HUSH_VERSION=0.01
target=pxe
devnum=1
localvar=hello
=> localvar=
=> showvar
HUSH_VERSION=0.01
target=pxe
devnum=1
localvar=hello
------------------------------------------------------

The 'localvar' still exists and is not deleted.
How do I delete a hush-shell local variable??

-Adarsh




<https://www.avast.com/en-in/recommend?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=default3&tag=263e577d-8a0d-4805-aed0-c94705b9fd3a>
I’m
protected online with Avast Free Antivirus. Get it here — it’s free forever.
<https://www.avast.com/en-in/recommend?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=default3&tag=263e577d-8a0d-4805-aed0-c94705b9fd3a>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

[U-Boot] [BUG] cmd : Local Hush Variable Could not be deleted

[Wolfgang Denk]

Dear Adarsh Babu Kalepalli,

In message <CAJgxa7c150OvA0bHPROWuizG+DvLrReRbqAoJ96QXkwhhhZsug@mail.gmail.com> you wrote:
> 
> How do I delete a hush-shell local variable??

You cannot.  Local variables can be set to an empty value, but they
cannot be deleted.

Note that there is no functional difference between a non-existing
local variable and one with an empty value anyway.  Same as in other
shells.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Carelessly planned projects take three times longer to complete  than
expected.  Carefully  planned  projects  take  four  times  longer to
complete than expected, mostly  because  the  planners  expect  their
planning to reduce the time it takes.

[U-Boot] [BUG] cmd : Local Hush Variable Could not be deleted

[Adarsh Babu Kalepalli]

 Hello Wolfgang Denk,

> => localvar=
> => showvar
> HUSH_VERSION=0.01
> target=pxe
> devnum=1
> localvar=hello

When 'localvar' is assigned an empty value , the 'showvar' command
displays the previously assigned 'hello'.

How do we set an empty value to a hush shell local variable ??

Regards,
Adarsh

On Mon, Oct 14, 2019 at 3:58 PM Wolfgang Denk <wd@denx.de> wrote:

> Dear Adarsh Babu Kalepalli,
>
> In message <
> CAJgxa7c150OvA0bHPROWuizG+DvLrReRbqAoJ96QXkwhhhZsug at mail.gmail.com> you
> wrote:
> >
> > How do I delete a hush-shell local variable??
>
> You cannot.  Local variables can be set to an empty value, but they
> cannot be deleted.
>
> Note that there is no functional difference between a non-existing
> local variable and one with an empty value anyway.  Same as in other
> shells.
>
> Best regards,
>
> Wolfgang Denk
>
> --
> DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
> Carelessly planned projects take three times longer to complete  than
> expected.  Carefully  planned  projects  take  four  times  longer to
> complete than expected, mostly  because  the  planners  expect  their
> planning to reduce the time it takes.
>

[U-Boot] [BUG] cmd : Local Hush Variable Could not be deleted

[Wolfgang Denk]

Dear Adarsh,

In message <CAJgxa7d3UPKdNcqegTE1ipOrBpx8jY4Q1MMyuWXQeKvTUbbGrQ@mail.gmail.com> you wrote:
>
> > => localvar=
> > => showvar
> > HUSH_VERSION=0.01
> > target=pxe
> > devnum=1
> > localvar=hello
>
> When 'localvar' is assigned an empty value , the 'showvar' command
> displays the previously assigned 'hello'.

Sorry, I missed that detail.


> How do we set an empty value to a hush shell local variable ??

You are right, this is a real bug. Not even using an explicit empty
string argument does work here:

U-Boot> foo=hello
U-Boot> showvar
HUSH_VERSION=0.01
foo=hello
U-Boot> foo=''
U-Boot> showvar
HUSH_VERSION=0.01
foo=hello



Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
It is better to marry than to burn.
                                - Bible ``I Corinthians'' ch. 7, v. 9