GRUB - Revision history

Kevin.Williams at 21:28, 18 April 2014

2014-04-18T21:28:24Z

Scott.morris at 19:15, 17 December 2013

2013-12-17T19:15:13Z

Scott.morris at 19:14, 17 December 2013

2013-12-17T19:14:22Z

Psullivan at 18:44, 17 December 2013

2013-12-17T18:44:11Z

Psullivan at 18:32, 17 December 2013

2013-12-17T18:32:51Z

Lynnae: add skip grub boot menu section

2012-08-08T18:39:31Z

add skip grub boot menu section

Scellef: /* Rooting a system */ fixed typo

2012-02-28T02:40:50Z

Rooting a system: fixed typo

Scellef: Added section on rooting from GRUB, categorized

2012-02-26T07:38:04Z

Added section on rooting from GRUB, categorized

Scellef: fixed typo

2012-02-26T07:07:38Z

fixed typo

Scellef: New page: Ubuntu 10.04 uses version 1.98 of GRUB (the '''GR'''and '''U'''nified '''B'''ootloader). For more information on bootloaders and the bootstrapping process, start [http://en.wikipedia.org/...

2011-07-23T01:20:08Z

New page: Ubuntu 10.04 uses version 1.98 of GRUB (the '''GR'''and '''U'''nified '''B'''ootloader). For more information on bootloaders and the bootstrapping process, start [http://en.wikipedia.org/...

New page

Ubuntu 10.04 uses version 1.98 of GRUB (the '''GR'''and '''U'''nified '''B'''ootloader). For more information on bootloaders and the bootstrapping process, start [http://en.wikipedia.org/wiki/Bootloader#Boot_loader | here].

==Opening the GRUB menu==
Reboot the computer, and either during or just after its POST (where a small blinking cursor like this <code>_</code> will appear in the upper left hand corner of the screen) press and hold down a '''Shift''' key. After a few moments, the text <code>Grub loading...</code> should flash and you'll be presented with a menu with options similar to this:

Ubuntu, with Linux 2.6.32-33-generic
Ubuntu, with Linux 2.6.32-33-generic (recovery mode)
Memory test (memtest86+)
Memory test (memtest86+, serial console 115200)

Here you can move up and down the list of images to boot from, edit their boot parameters, open the GRUB command-line for advanced trickery, and more.

==Adding rootdelay==
Occasionally a system will fail to boot from a known good, imaged hard drive. Sometimes it's because of defective hardware, and all we can do is replace the parts. But sometimes it's because the bootloader doesn't wait long enough for the drive to respond, and all we need to do is tell the bootloader to wait for just a little longer!

From the GRUB menu:
* Highlight the standard kernel (usually something like <code>Ubuntu, with Linux 2.6.32-33-generic</code>), and press '<code>e</code>'. You should see something similar to this:

recordfail
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set 732c5f94-8dcb-4622-96ea-797dd2431f90
linux /boot/vmlinuz-2.6.35-30-generic root=UUID=732c5f94-8dcb-4622-96ea-797dd2431f90 ro quiet splash
initrd /boot/initrd.img-2.6.35-30-generic

* Scroll down to the line that starts with <code>linux</code> then scroll to end of the line after <code>splash</code>
* Enter '<code>rootdelay=60</code>'
* Hit '''Ctrl+x''' to boot the image with modified parameters.

The argument for rootdelay is in seconds, though it almost never times out. Most things that would happen with a drive, whether it was working or not, happen relatively quickly.

In order to make this a permanent boot parameter, you can edit the file '''/etc/default/grub''' and add <code>rootdelay=60</code> to the list of arguments assigned to the variable <code>GRUB_CMDLINE_LINUX_DEFAULT</code>.

← Older revision		Revision as of 21:28, 18 April 2014
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		+	{{migrated}}
		+
		+	[https://docs.google.com/a/freegeek.org/document/d/1baAFRGqdXEzF58VkTOY21qrrzO55kaKo0xhHrxBk_2k/edit?usp=sharing Link]
		+
	Ubuntu 12.04 uses GRUB (the '''GR'''and '''U'''nified '''B'''ootloader). For more information on bootloaders and the bootstrapping process, start [http://en.wikipedia.org/wiki/Bootloader#Boot_loader here].		Ubuntu 12.04 uses GRUB (the '''GR'''and '''U'''nified '''B'''ootloader). For more information on bootloaders and the bootstrapping process, start [http://en.wikipedia.org/wiki/Bootloader#Boot_loader here].

@@ Line 74: / Line 74: @@
   <code>$ sudo update-grub</code>
-The resolution can be customized by changing '640x480' to the native resolution of the monitor. e.g. '1024x768'
+The resolution can be customized by changing '640x480' to a resolution supported by the monitor. e.g. '1024x768'
 [[Category:Howto]] [[Category:Tech support]]

← Older revision		Revision as of 19:14, 17 December 2013
Line 61:		Line 61:

	In order to make this a permanent boot parameter, you can edit the file '''/etc/default/grub''' and add <code>rootdelay=60</code> to the list of arguments assigned to the variable <code>GRUB_CMDLINE_LINUX_DEFAULT</code>.		In order to make this a permanent boot parameter, you can edit the file '''/etc/default/grub''' and add <code>rootdelay=60</code> to the list of arguments assigned to the variable <code>GRUB_CMDLINE_LINUX_DEFAULT</code>.
		+
		+	==GRUB fails to detect proper resolution==
		+
		+	Sometimes GRUB fails to detect the correct resolution for a monitor or graphics card. This issue is characterized by an "Input Not Supported" error from the monitor. Pressing enter should boot the system normally.
		+
		+	To permanently set the resolution modify the /etc/default/grub file.
		+
		+	*Use your favorite text editor to open the config file.
		+	<code>$ sudo nano /etc/default/grub</code>
		+	*Locate the line that reads <code>'#GRUB_GFXMODE=640x480'</code> and uncomment it by removing the the preceding hashtag.
		+	*Update grub
		+	<code>$ sudo update-grub</code>
		+
		+	The resolution can be customized by changing '640x480' to the native resolution of the monitor. e.g. '1024x768'
		+

	[[Category:Howto]] [[Category:Tech support]]		[[Category:Howto]] [[Category:Tech support]]

← Older revision		Revision as of 18:44, 17 December 2013
Line 1:		Line 1:
−	Ubuntu 10.04 uses ~~version 1.98 of~~ GRUB (the '''GR'''and '''U'''nified '''B'''ootloader). For more information on bootloaders and the bootstrapping process, start [http://en.wikipedia.org/wiki/Bootloader#Boot_loader here].	+	Ubuntu 12.04 uses GRUB (the '''GR'''and '''U'''nified '''B'''ootloader). For more information on bootloaders and the bootstrapping process, start [http://en.wikipedia.org/wiki/Bootloader#Boot_loader here].

	==Opening the GRUB menu==		==Opening the GRUB menu==

← Older revision		Revision as of 18:32, 17 December 2013
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	In order to make this a permanent boot parameter, you can edit the file '''/etc/default/grub''' and add <code>rootdelay=60</code> to the list of arguments assigned to the variable <code>GRUB_CMDLINE_LINUX_DEFAULT</code>.		In order to make this a permanent boot parameter, you can edit the file '''/etc/default/grub''' and add <code>rootdelay=60</code> to the list of arguments assigned to the variable <code>GRUB_CMDLINE_LINUX_DEFAULT</code>.

−	[[Category:Howto]]	+	[[Category:Howto]] [[Category:Tech support]]

← Older revision		Revision as of 18:39, 8 August 2012
Line 10:		Line 10:

	Here you can move up and down the list of images to boot from, edit their boot parameters, open the GRUB command-line for advanced trickery, and more.		Here you can move up and down the list of images to boot from, edit their boot parameters, open the GRUB command-line for advanced trickery, and more.
		+
		+	==Bypassing GRUB boot menu==
		+	Sometimes, especially when installing Ubuntu from an optical disk, GRUB will default to showing a boot menu before booting to the operating system.
		+
		+	To bypass this:
		+	*Open a terminal and run
		+	$ sudo gedit /etc/default/grub
		+	*find the '''GRUB_TIMEOUT=''' line and change the number value to 0
		+	*save your changes
		+	*run
		+	$ sudo update-grub
		+	*restart and verify that the boot menu is no longer showing

	==Rooting a system==		==Rooting a system==

@@ Line 20: / Line 20: @@
 * Hit '''Ctrl+x''' to boot the image with modified parameters.
 * You should almost immediately be dropped to a root shell.  Bear in mind that replacing <code>init</code> with a shell prevents it from loading any modules or applying any standard configurations or settings.  That is to say, ''this environment is fragile and you should tread lightly''!
-* The next step is to modify the root password.  In general, it's a good idea to back up the old password.  In order to do either of these things, we need to mount the filesystem as writable.  Run the following command:<br /><code># mount /dev/sda1/ -o remount,ro /</code><br /> Where <code>/dev/sda1</code> is your root partition.
+* The next step is to modify the root password.  In general, it's a good idea to back up the old password.  In order to do either of these things, we need to mount the filesystem as writable.  Run the following command:<br /><code># mount /dev/sda1/ -o remount,rw /</code><br /> Where <code>/dev/sda1</code> is your root partition.
 * Now, run:<br /><code># cp /etc/shadow /root/shadow.bak</code><br />This creates a backup of the current root password
 * Finally, run <br /><code># passwd root</code><br />You will be prompted to enter a new password for the root account.  Once this is done, reboot the computer and log in as root at your leisure!

@@ Line 10: / Line 10: @@
 Here you can move up and down the list of images to boot from, edit their boot parameters, open the GRUB command-line for advanced trickery, and more.
 ==Adding rootdelay==
 Occasionally a system will fail to boot from a known good, imaged hard drive.  Sometimes it's because of defective hardware, and all we can do is replace the parts.  But sometimes it's because the bootloader doesn't wait long enough for the drive to respond, and all we need to do is tell the bootloader to wait for just a little longer!
@@ Line 32: / Line 49: @@
 In order to make this a permanent boot parameter, you can edit the file '''/etc/default/grub''' and add <code>rootdelay=60</code> to the list of arguments assigned to the variable <code>GRUB_CMDLINE_LINUX_DEFAULT</code>.

← Older revision		Revision as of 07:07, 26 February 2012
Line 1:		Line 1:
−	Ubuntu 10.04 uses version 1.98 of GRUB (the '''GR'''and '''U'''nified '''B'''ootloader). For more information on bootloaders and the bootstrapping process, start [http://en.wikipedia.org/wiki/Bootloader#Boot_loader \| here].	+	Ubuntu 10.04 uses version 1.98 of GRUB (the '''GR'''and '''U'''nified '''B'''ootloader). For more information on bootloaders and the bootstrapping process, start [http://en.wikipedia.org/wiki/Bootloader#Boot_loader here].

	==Opening the GRUB menu==		==Opening the GRUB menu==