You could use the environment block:
https://www.gnu.org/software/grub/manual/html_node/Environment-block.html
But I believe that kind of logic is supposed to go into the scripts that
generate your grub.cfg when you run update-grub, and not into the generated
grub.cfg itself.
On July 17, 2015 3:12:36 PM GMT+01:00, Marc Smith <[email protected]> wrote:
>Hi,
>
>Looking for any possibility of reading the contents of a file (or even
>just
>the file name) into a variable in a GRUB config file? I've read that
>command substitution is not supported and no plans to add it, but is
>there
>any other way?
>
>I've tried a couple other methods without success (in the grub.cfg
>file):
>--snip--
>while read ver_str;
>do
> something_with ${ver_str}
>done < /version_file
>--snip--
>
>OR
>
>--snip--
>cat /version_file | while read ver_string;
>do
> something_with ${ver_str}
>done
>--snip--
>
>The goal is to read a "version string" from a file at boot with GRUB to
>display different menu entries for different versions, but I'd even
>take
>just getting the string from the file name at this point. Any ideas? My
>last resort is to just use sed to modify grub.cfg when a new version of
>the
>OS is installed (for a new GRUB menu entry), but I'd prefer not to do
>that
>unless I have to.
>
>Or what about including another grub.cfg file and then in the included
>GRUB
>config file just have the line "set ver_str=0.1.1" -- I was thinking
>using
>the 'configfile' command would do this, but doesn't seem to work as I
>expected.
>
>Any help or ideas would be greatly appreciated.
>
>
>Thanks,
>
>Marc
>
>
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>
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