Re: change default os

[Jordan Uggla]

On Wed, Mar 13, 2013 at 9:52 AM, Simon Hobson <address@hidden> wrote:
> pete tridish wrote:
>>- i am helping a farmworkers group to set up a radio studio, and one of the 
>>computers was set up with grub, and defaults to linux on reboot.   
>>unfortunately, i need it to default to windows--- the linux program we were 
>>going to use for the automation was not ready yet, so we switched to windows. 
>> I'd rather not wipe out the linux now, since we may switch over when the 
>>linux software is ready.
>>
>>but the way it stands, any time the power goes out, it boots back in to linux 
>>and the guys here get totally lost. the computer stuff needs to work as 
>>simply as possible, without much human intervention, because the language 
>>barrier is a big issue in keeping the station running.
>>
>>how can i change it so that the default OS is windows?   it is grub loader 
>>version 1.99
>
> Some of this is Distro dependent, I can only speak for Debian.
>
> If you edit /boot/grub/grub.cfg and change where it says 'set default="0"' to 
> the index of teh OS you want to boot, that will do it **BUT** the change will 
> be wiped out next time Gurb updates it's config.

Since it will get wiped out, it's hardly worth mentioning at all.

>
> To make the change permanent, make the same change in /etc/default/grub and 
> then run "update-grub" to update /boot/grub/grub.cfg.
>
> Both these will allow you to change the default OS to boot, but it's done by 
> index into the list. If the list changes (such as installing an updated 
> kernel) then your index will be wrong and you'll boot something else.

That's why GRUB_DEFAULT can be set to a menu entry title, so that it
will continue working no matter how many entries come before the one
you want.

>
> An alternative way is to re-order the components in /etc/grub. On my Debian 
> system, Windows (and others) are detected by30_os-prober - if you change the 
> numbering so this comes before nn_linux, then the Windows OS will come before 
> Linux in the list, meaning Windows will boot by default. You'll need to take 
> care to deal with this change any time Grub gets updated and the installer 
> wants to put new config files in.

Hence it's hardly worth mentioning. I highly recommend against doing
this. My general feeling is that you should never make any changes in
/etc/grub.d/ at all (only modifying /etc/default/grub is enough for
95% of people, and for 4 of the next 5% adding custom entries via
/boot/grub/custom.cfg is enough). If you're in the 1% that can't get
what you need/want from grub-mkconfig without modifying /etc/grub.d/
then I would recommend writing your grub.cfg completely manually.

-- 
Jordan Uggla (Jordan_U on irc.freenode.net