Re: [PATCH] install.sh: Preserve directory symlinks

[Jan Beulich <jbeulich@xxxxxxxx>]

On 19.03.2026 14:59, Thierry Escande wrote:
> On 3/19/26 14:48, Jan Beulich wrote:
>> On 19.03.2026 14:26, Thierry Escande wrote:
>>> On 3/19/26 10:31, Jan Beulich wrote:
>>>> On 13.03.2026 18:25, Thierry Escande wrote:
>>>>> In various distros (i.e. Debian) some folders like /lib or /var/run are
>>>>> symlinks. Using the tar option --keep-directory-symlink preserves these
>>>>> symlinks.
>>>>>
>>>>> Signed-off-by: Thierry Escande <thierry.escande@xxxxxxxxxx>
>>>>> ---
>>>>>  install.sh | 2 +-
>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/install.sh b/install.sh
>>>>> index 3e11c4d46f..5d0b7a4933 100644
>>>>> --- a/install.sh
>>>>> +++ b/install.sh
>>>>> @@ -27,7 +27,7 @@ tmp="`mktemp -d`"
>>>>>  echo "Installing Xen from '$src' to '$dst'..."
>>>>>  (cd $src; tar -cf - * ) | tar -C "$tmp" -xf -
>>>>>  
>>>>> -(cd $tmp; tar -cf - *) | tar --no-same-owner -C "$dst" -xf -
>>>>> +(cd $tmp; tar -cf - *) | tar --no-same-owner -C "$dst" 
>>>>> --keep-directory-symlink -xf -
>>>>
>>>> How compatible (between flavors of tar as well as between versions of GNU
>>>> tar) is use of this option?
>>>
>>> It's supported by GNU tar since version 1.27 (from ~12 years ago) but it
>>> seems to be the only implementation that supports it. BSD and busybox
>>> don't support it. I didn't check for other implementations.
>>>
>>> I can add a flavor/version check if that makes sense.
>>
>> Possibly. One question then is what the behavior was prior to that option
>> having been introduced.
> 
> From the patch at [1] introducing the option, and more precisely the
> test done at [2], directory symlinks were simply overwritten.

Which makes it hard to suggest useful behavior when the option is unavailable:
Simply refusing to install isn't nice, but corrupting the installation is
perhaps even worse.

I take it that the (presumably) more standard -h doesn't help here?

Jan

> [1]
> https://cgit.git.savannah.gnu.org/cgit/tar.git/commit/?id=2c06a80918019471876956eef4ef22f05c9e0571
> [2]
> https://cgit.git.savannah.gnu.org/cgit/tar.git/tree/src/extract.c?id=2c06a80918019471876956eef4ef22f05c9e0571#n934
> 
> Regards,
> Thierry
> 
> 
> --
> Thierry Escande | Vates XCP-ng Developer
> 
> XCP-ng & Xen Orchestra - Vates solutions
> 
> web: https://vates.tech
>