Re: Grub version variable in shell

[Andreas Born]

Am 11.03.2012 03:51, schrieb Vladimir 'φ-coder/phcoder' Serbinenko:
> On 11.03.2012 03:40, Andreas Born wrote:
> > Hi,
> >
> > it would be great to have a variable like version or grub_version in
> > the shell. Sorry, if there is already such an option and I didn't find
> > it. But I only saw cpu and platform as well as the feature variables.
> >
> > This is useful, if you want to use some new feature or don't want to
> > use some ugly workaround anymore, which you needed for an older version.
> We don't use grub_version because it would give only very approximate
> idea of features supported and so only marginally useful and is likely
> to make devs use suboptimal method. Instead we define variables like
> feature_foo. Good example is from root setting code:
> if [ x$feature_platform_search_hint = xy ]; then
>    search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt10
> --hint-efi=hd0,gpt10 --hint-baremetal=ahci0,gpt10  UUID
> else
>    search --no-floppy --fs-uuid --set=root UUID
> fi
Thank you, I get your point.
Still I think version can be useful to exclude versions with bugs (or 
features) they do/(don't) have. For example on 1.98 I had to reexport 
all variables in every configfile. This was dirty and hard to maintain 
so I do not want to maintain this anymore. Instead of silently failing, 
I'd like to provide users of older versions with a very simple menu 
combined with a warning. (Usually in normal boot scenarios they're using 
my grub build anyway.) I don't see how this should be possible without 
my 'if keymap' hack. I think neither checking for a command existence 
nor a feature is a reliable method to always ensure a minimum version. 
Of course if you have a better idea, that's even more welcome.
Maybe something like a grub_version_min command? And possibly *_max?

Apart from that I guess it would be nice to have such a variable to 
display the version someplace or to check it. Yes, I know it is already 
displayed in multiple places, but I don't think in gfxmenus.

Did those feature variables even exist in 1.99?
> > Currently, I'm doing a check like 'if keymap' to show a minimal menu
> > to pre-1.99 users with a warning that they're version is too old
> > instead of giving them garbage if at all. But that check does not feel
> > really reliable nor clean. ;)
> > Especially given the recent discussion regarding backwards
> > incompatible changes, this would be a really big help even if they're
> > only small changes. But I imagine there are other uses too. The early
> > there is such a variable the more useful it is, but I wouldn't
> > consider it critical.
> >
> > On the other hand it's quite hard to parse a version string on the
> > grub shell, especially if distributions choose to change it to some
> > Brainf**k imitation. Or they give the code a major revamp and then
> > don't change it. Well, maybe grub could get a Brainf**k parser at
> > least. :D
> >
> > For completeness two-line patch attached. (Untested)
> >
> > Andreas Born
> >
> >
> > _______________________________________________
> > Grub-devel mailing list
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> > https://lists.gnu.org/mailman/listinfo/grub-devel
>
>
>
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