update-grub question
 

How do I get update-grub to scan an entire drive to look for changes (rather than just scanntng the partition in which its distro is located)?

geno

What do you exactly mean by this ?
During install GrUB automaticly scans for other distro.
If you install a other distro the menu.lst of the new one is up to date
Some distro also gives the option after install to update the boot loader
automaticly , but updating manually is always possible

ronlau9,

The question arose in connection with this article:

http://www.brighthub.com/computing/l...les/36648.aspx

Obviously I want to avoid the grub-on-grub-on-grub phenomenon each time I add a distro to my system. Now I pull out the Windows disk, run fixmbr destroying grub, and then let the new distro install grub afresh in the MBR. There must be a tidier non-arduous way to update the boot menu in the MBR!

geno

update-grub question
 

when you install each distro, after you create your partition, the next page presents options for the boot loaders... simply indicate on that page which partition is going to have the grub, and the install should recognize the other partitions and properly load one grub.conf file with all your linux options.
This should work, shouldn't it?

Let assume you like to install 4 linux distros
You have divided you're hard disk in 4 partitions
Let start which the distro in the last namely partition 4 install it over there and write GRUB in boot sector of partition 4 .
We do the same with partition 3 and partition 2
The distro in partition 1 we write GRUB in MBR
Normally the last distro is aware of the other distros in partition 2 up to four and updated its menu.lst or whatever it use to boot the other distros
In the menu.lst you will find all the installed distro
If this is going wrong for one reason or they other , we can always add it manually.
How exactly depends on the linux flavour in qeustion
MBR is only 512 bytes so you're menu.lst is not there.
You will find it in /boot/GRUB/menu.lst

But this only one way to do a multi boot there other ways to accomplish it.
I hope this make it somewhat clear how to do it

The easiest way I have found for adding and changing distros is by chainloading but as ronlau9 said there are three or four different ways.

update-grub is not a part of grub - it is an added wrapper. Most notably on Debian derived distros - it is not shipped on all distros. Consequently, it is not run if you re-run grub-install - which *is* part of the grub project.
Being a script you are free to peruse and adapt update-grub should you feel the desire.

The running around finding other distros on your system is done by the distro installer, not grub (installer) or update-grub.

If I remember right you need to build your own menu.lst when installing grub without the aid of a distro.