Section: 38 GRUB

Question 1

GRUB GRUB

What is Grub?

Answer 1

• Vertually all x86 linux systems today use GRUB to handle the early phases fo the system start up.
• Important features of GRUB;
  
  1. alternative operating systems can be chosen at boot time
  2. alternative kernels and /or intial ramdisks can be chosen at boot time for a given operationing system.
  3. Boot parameters can be easily changed at boot time without having to edit configuration files, etc. in advance.

Question 2

At boot, a basic configuration file is read.

what are the possible files that are used ?

Answer 2

• /boot/grub/grub.cfg
• /boot/grub2/grub.cfg
• /boot/efi/EFI/redhat/grub.cfg

Question 3

The GRUB basic configuration file is _____________ by update-grub

or (grub2-mkconfig).

Answer 3

• auto generated
  
  • should not be edited by hand.

Question 4

• Education: Grub
  
  • Installing Grub can have several different meanings:
    
    1. installing the grub program and associated utilities
       
       • In GRUB 1 there is usaly a program just called grub, but in GRUB2 there are a bunch of utlities with names like grub2-* or grub-*
         
         • how they are packaeged is different depending on the distribution.
    2. Installing the files GRUB needs to operate at boot time under either
       
       1. / boot/grub
       2. or /boot/grub2
    3. Installing GRUB as the boot loader in the system.
       
       1. this can be done :
          
          1. at the front of the hard disk
          2. in a partition
          3. or accessed via chainloading from one GRUB to another.

Answer 4

• If I am instlling GRUB 1 what is the program called that i need to install?

Question 5

• Education: Grub
  
  • Installing Grub can have several different meanings:
    
    1. installing the grub program and associated utilities
       
       • In GRUB 1 there is usaly a program just called grub, but in GRUB2 there are a bunch of utlities with names like grub2-* or grub-*
         
         • how they are packaeged is different depending on the distribution.
    2. Installing the files GRUB needs to operate at boot time under either
       
       1. / boot/grub
       2. or /boot/grub2
    3. Installing GRUB as the boot loader in the system.
       
       1. this can be done :
          
          1. at the front of the hard disk
          2. in a partition
          3. or accessed via chainloading from one GRUB to another.

Answer 5

• When installing GRUB as the boot loader , what are the three places i could have it stored?

Question 6

• Education: Grub
  
  • Installing Grub can have several different meanings:
    
    1. installing the grub program and associated utilities
       
       • In GRUB 1 there is usaly a program just called grub, but in GRUB2 there are a bunch of utlities with names like grub2-* or grub-*
         
         • how they are packaeged is different depending on the distribution.
    2. Installing the files GRUB needs to operate at boot time under either
       
       1. / boot/grub
       2. or /boot/grub2
    3. Installing GRUB as the boot loader in the system.
       
       1. this can be done :
          
          1. at the front of the hard disk
          2. in a partition
          3. or accessed via chainloading from one GRUB to another.

Answer 6

• the files that grub needs to operate at boot time are located where?

Question 7

• Grub Versions:
  
  • In both versions , the first hard drive is denoted:
    
    • hd0

Answer 7

• In Grub what is the name of the first hard drive

Question 8

• In Grubs configuration file, each stanza has to specify what the root partition is. This is not the same as what we mean when we talk about the root directory system.

Answer 8

• The grub configuration file :
  
  • In each stanza has to specify ________?

Question 9

• when we are speaking about a root partition wrt GRUB,
  
  • it means the partition contains the kernel itself (in the /boot directory.
  • example:
    
    • it is very common for the to have /boot in its own partition . Lets say /dev/sda1

Answer 9

• What does it mean when we are speaking of the root partition wrt GRUB?

Question 10

• Grub configuation files:
  
  • Remeber that I should not edit the grub.cfg file directly.

Answer 10

Should I edit the grub.cfg directly?

Question 11

• Grub configuration files :
  
  • There are two locations in the /etc directory that would need attention and are used to rebuild the grub.cfg file when the system is changed with new kernels.
    
    • these are :
      
      1. /etc/default/grub
      2. /etc/grub.d

Answer 11

what the two locations in the /etc directory that would need to be attention and are used to rebuild the grub.cfg file?

Question 12

• Grub Configuration files:
  
  • Each of the two files( /etc/default/grub and /etc/grub.d) run in ascending order when the file is updated.

Answer 12

• do the files :
  
  • /etc/default/grub
  • /etc/grub.d
• run in ascending or descending order when updated?

Question 13

• Boot loader specification configuration:
  
  • On systems configured with BLSCFG a person would still use the usual grub commands when installing or updating kernels, etc.

Answer 13

on systems where BLSCFG is installed would I still use the usual grub commands when installing or updating kernels?

Question 14

• Boot Loader specification configuration:
  
  • When a systen is configured with BLSCFG there are some details to remember:
    
    • while the file /boot/grub2/grub.cfg still exists detailed informantion and options for each kernel that can be chosen appears in :
      
      • /boot/loader/entries

Answer 14

When your system is configured with BLSCFG detailed information and options for each kernel that can be chosen is located where?

Question 15

With the boot loader specification configuration scheme, each possible kernel

gains an entry in what file?

Answer 15

/boot/loader/entries

Question 16

/boot/grub2/grubenv sets the _____ ________ ______ ?

Answer 16

/boot/grub2/grubenv set the default boot kernel .

Question 17

In the location /boot/grub2/grubenv there are a number of

envorinmental variables that may be set. what are they?

Answer 17

• kernelopts
• tuned_initrd
• tuned_params
• grub_users

Question 18

Where are the GRUB configuration variables located?

Answer 18

/etc/default/grub

Question 19

the directory /etc/grub.d contains …..?

Answer 19

scripts use to build GRUB’s menu