Re: How to remove variable from GRUB environment block

[Andrey Borzenkov]

В Tue, 12 Feb 2013 14:57:53 +0100
Ulf Zibis <address@hidden> пишет:

> Am 12.02.2013 03:15, schrieb Andrey Borzenkov:
> > В Mon, 11 Feb 2013 20:52:12 +0100
> > Ulf Zibis <address@hidden> пишет:
> >
> >> Am 11.02.2013 17:46, schrieb Andrey Borzenkov:
> >>> For all practical purposes, empty variable is the same as non-existing
> >>> variable.
> >> Not really, testing for non-existence would fail.
> > How do you test for variable existence in grub?
> 
> I'm not clearly sure, but I see different syntax in my grub.cfg, which I 
> interpret as "test for 
> existence":
> 

No. Both just test whether result of variable substitution is empty or
not. It is empty if variable is not defined or if it is defined but
empty.

> if [ x"${feature_menuentry_id}" = xy ]; then
>    ...
> 
> if [ "${prev_saved_entry}" ]; then
>    set saved_entry="${prev_saved_entry}"
> fi
> 
> 
> -Ulf
>