GrubHowto

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CategoryDocumentation CategoryDocumentation CategoryCleanup

Other Languages: ComoGrub (Spanish)

What Is GRUB

GRUB is a bootloader, it is the first thing that loads when the computer starts. It allows you to have different operating systems, and versions of them, on the same hard drive. For example you may have Windows and Linux on a computer, GRUB would load before either of these and give you a choice. You can also create a boot floppy with GRUB to use in case of emergency.

Increasing the GRUB timeout

If you need to get into the grub menu you need to press ESC just after it starts. By default you have to press ESC very quickly. To increase this time edit /boot/grub/menu.lst, increasing the seconds in the TIMEOUT part. Alternatively you could have the menu always come up at boot time. To do this, comment out 'hiddenmenu' by inserting a # at the beginning of the line. Once you have changed menu.lst you must run:

$ sudo update-grub

Note that if the Ubuntu installer detected other operating systems on the disk during the installation, then the grub menu will be displayed by default and the timeout will be increased, so the step above will be unnecessary.

Setting kernel parameters

In /boot/grub/menu.lst, you will find a line like this:

# kopt=root=/dev/sda1 ro

It is a comment, but do not remove the '# ' at the beginning. THIS IS IMPORTANT.

If you require additional kernel parameters (for example, if someone has asked you to test booting with certain parameters in order to troubleshoot a problem), add them to the end of the line, for example to add noapic:

# kopt=root=/dev/sda1 ro noapic

After editing the file, run:

$ sudo update-grub

at the command line.


CategoryDocumentation CategoryCleanup

GrubHowto (last edited 2008-08-06 16:19:46 by localhost)