Re: [GTALUG] GRUB's DSL and looping
On Wed, 25 Jul 2018 at 14:14, Lennart Sorensen via talk wrote: > > On Wed, Jul 25, 2018 at 02:09:00PM -0400, Giles Orr wrote: > > I don't think that's documented anywhere, and it doesn't strike me as being > > in any way obvious. > > Well it's vaguely documented in that the module has a description. > And it is totally not obvious that a module could change such behaviour > in the first place. Is there some place to push a documentation patch for that? It's managed at Savannah, so there's a git repo, and it sure seems a neat idea to augment it... git clone git://git.savannah.gnu.org/grub.git -- When confronted by a difficult problem, solve it by reducing it to the question, "How would the Lone Ranger handle this?" --- Talk Mailing List talk@gtalug.org https://gtalug.org/mailman/listinfo/talk
Re: [GTALUG] GRUB's DSL and looping
On Wed, Jul 25, 2018 at 02:09:00PM -0400, Giles Orr wrote: > I don't think that's documented anywhere, and it doesn't strike me as being > in any way obvious. Well it's vaguely documented in that the module has a description. And it is totally not obvious that a module could change such behaviour in the first place. -- Len Sorensen --- Talk Mailing List talk@gtalug.org https://gtalug.org/mailman/listinfo/talk
Re: [GTALUG] GRUB's DSL and looping
On 25 July 2018 at 13:45, Lennart Sorensen via talk wrote:
> On Wed, Jul 25, 2018 at 12:54:39PM -0400, Giles Orr via talk wrote:
> > There's probably a GRUB-specific mailing list or forum, but I thought I
> > would try here first ...
> >
> > GRUB has a DSL ( https://en.wikipedia.org/wiki/Domain-specific_language
> )
> > that looks a lot like shell scripting. Most people never see it as it's
> > used to generate the menus we use at boot-time and they see only the
> menus,
> > but it can do some interesting things - particularly when you're dealing
> > with multi-boot USB sticks. Here's a simple but slightly useful example:
> >
> > function cpuinfo {
> > # only able to determine: 32/64 bit, and is it PAE
> > echo "GRUB's ability to analyse processors is limited, we can only
> tell
> > you:"
> > if cpuid -p; then
> > pae_assessment="PAE"
> > else
> > pae_assessment="NO PAE"
> > fi
> > if cpuid -l; then
> > echo "64-bit processor, $pae_assessment"
> > else
> > echo "32-bit processor, $pae_assessment"
> > fi
> > }
> >
> > But it has some nasty limitations that are frustrating me:
> > - no pipes
> > - no command substitution
> > - no file globbing
>
> Actually it does file globbing if you load the regexp module.
>
> Apparently this works:
>
> insmod regexp
> for i in /boot/*; do echo $i; done
>
> Or:
>
> grub> ls /boot/*
> error: file `/boot/*' not found.
> grub> insmod regexp
> grub> ls /boot/*
> unicode.pf2 i386-pc/ locale/ fonts/ grubenv grub.cfg
> config-4.16.0-2-amd64
> ...
>
Thank you!
I don't think that's documented anywhere, and it doesn't strike me as being
in any way obvious.
--
Giles
https://www.gilesorr.com/
giles...@gmail.com
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Re: [GTALUG] GRUB's DSL and looping
On Wed, Jul 25, 2018 at 12:54:39PM -0400, Giles Orr via talk wrote:
> There's probably a GRUB-specific mailing list or forum, but I thought I
> would try here first ...
>
> GRUB has a DSL ( https://en.wikipedia.org/wiki/Domain-specific_language )
> that looks a lot like shell scripting. Most people never see it as it's
> used to generate the menus we use at boot-time and they see only the menus,
> but it can do some interesting things - particularly when you're dealing
> with multi-boot USB sticks. Here's a simple but slightly useful example:
>
> function cpuinfo {
> # only able to determine: 32/64 bit, and is it PAE
> echo "GRUB's ability to analyse processors is limited, we can only tell
> you:"
> if cpuid -p; then
> pae_assessment="PAE"
> else
> pae_assessment="NO PAE"
> fi
> if cpuid -l; then
> echo "64-bit processor, $pae_assessment"
> else
> echo "32-bit processor, $pae_assessment"
> fi
> }
>
> But it has some nasty limitations that are frustrating me:
> - no pipes
> - no command substitution
> - no file globbing
Actually it does file globbing if you load the regexp module.
Apparently this works:
insmod regexp
for i in /boot/*; do echo $i; done
Or:
grub> ls /boot/*
error: file `/boot/*' not found.
grub> insmod regexp
grub> ls /boot/*
unicode.pf2 i386-pc/ locale/ fonts/ grubenv grub.cfg
config-4.16.0-2-amd64
...
--
Len Sorensen
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[GTALUG] GRUB's DSL and looping
There's probably a GRUB-specific mailing list or forum, but I thought I
would try here first ...
GRUB has a DSL ( https://en.wikipedia.org/wiki/Domain-specific_language )
that looks a lot like shell scripting. Most people never see it as it's
used to generate the menus we use at boot-time and they see only the menus,
but it can do some interesting things - particularly when you're dealing
with multi-boot USB sticks. Here's a simple but slightly useful example:
function cpuinfo {
# only able to determine: 32/64 bit, and is it PAE
echo "GRUB's ability to analyse processors is limited, we can only tell
you:"
if cpuid -p; then
pae_assessment="PAE"
else
pae_assessment="NO PAE"
fi
if cpuid -l; then
echo "64-bit processor, $pae_assessment"
else
echo "32-bit processor, $pae_assessment"
fi
}
But it has some nasty limitations that are frustrating me:
- no pipes
- no command substitution
- no file globbing
That last in particular is really getting on my nerves. I want to source
all the files in one folder, but I can't say 'for file in folder/* ; do'
because the '*' is a literal character, no special meaning. Likewise, I
can't say 'for file in `ls folder/` ; do' because there's no command
substitution.
I was wondering if anyone knows of a solution to this problem. Or even if
you have ideas from long-gone old shells with similar limitations for which
someone worked out a nasty work-around ... What I've been doing is 'for
file in name1 name2 name3 ... ; do', but of course this only works if you
remember to add new filenames to the list.
I've googled quite a bit, but most people only modify GRUB through
/etc/default/grub or, if they're really adventurous, through
/etc/grub.d/40_custom or similar. What I'm looking for is (mostly) at a
lower level than that, and examples are surprisingly hard to come by. And
search results are occasionally polluted by GRUB4DOS results ... GRUB4DOS
_does_ seem to support file globbing. All very confusing. Thanks.
--
Giles
https://www.gilesorr.com/
giles...@gmail.com
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