Episode: 50
Title: HPR0050: Linux Boot Process Part 2B - Grub
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr0050/hpr0050.mp3
Transcribed: 2025-10-07 10:47:46

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Hello, welcome to another exciting episode of Hacker Public Radio, my name is Dan
Washco and I'm continuing my series of Delinix startup or boot process today with
episode 2b or actually 3 whatever you want to call my episode on grub and no
I'm not talking about those tasty little beetle larvae that a lot of countries
find very nutritious and supplement their protein intake with but I am
talking or slying for food for that matter but no I am talking about the boot
loader of the gods grub the grand unified boot loader this I'm excited to
talk about grub because grub is it's just awesome and I hope that you find grub
as awesome as I do because it's just it is it is fun it is exciting and it is
just all around goodness wrapped up in a little boot loader now a lot of my
information was called from the very informative very useful grub manual which
can be found on the grub website which is very easy to access at www.gnu.org
slash software slash grub that's off the GNU website and grub is a
application under the GNU public license it is currently on version 0.97 which
is the version that most distributions install with and you know one of the
things that's really cool and you probably take for granted is that when you
run your OS you're actually running two kind of systems there I mean well
three if you you could say you got the BIOS which loads in which kicks off the
boot process boot loader which isn't part of the operating system so to speak
it's its own little consider operating system and no other boot loader I've
seen other than grub really exemplifies this and we'll get to that in a few
moments and then your boot loader in this case grub will kick off the loading of
your operating system of choice now what's really cool about grub is not only
do you get to set it up but you can also configure it on the fly unlike
lilo the Linux loader which I talked about last time you install the Linux
loader and you hope it you know you got everything right for the next time you
try and boot grub on the other hand it is not that limited if if something's
wrong grub has essentially three modes there's a menu mode which is
what most people will see when they boot grub if they see grub at all which
provides you a list of definitions OS definitions as you can boot there is the
edit mode where when you're in the menu mode you can press the e button and
begin edit any one of those definitions or there is the command line mode which
allows you to just access the grub command line mode and you could do a whole
lot more on the command line mode which we'll get into shortly now grub has
supplanted lilo as the main Linux bootloader of choice for most
distributions now I do believe slackware is one of the few that are left that
uses lilo to this day as default bootloader arch Linux gives you a choice
and so does Gentoo give you a choice when you're installing the operating
system as to which bootloader you want to use now if if you are at all has a
10 you know you might be familiar with lilo very very familiar with lilo
hopefully after this you will elect to choose to install grub as your default
bootloader for any operating system that you want to run it is that awesome
now most people are not going to have to worry about installing grub pulling
down the sources or building grub yourself or unless you're again running
arch or Gentoo you probably won't even be asked what loader you want to run
you'll be asked do you want to install it in the master boot record or in the boot
partition of your root partition given that I'm not really going to go into the
details of installing grub from source you can get that from the documentation
most people will not have to do that but given that when you install when you
install your your distribution of choice and you go through and it prepares to
install the bootloader unlike lilo or some other bootloaders you don't really
have to have much configured for grub when you run the grub install now there are
a few configuration files and if you read the documentation it's of course a
documentation tries to be operating system agnostic but we're going to be
focusing on documentation for Linux or GNU Linux and where the majority of
distributions install grub and this configuration files will be found in the
slash boot slash grub directory you will also find command grub commands in the
slash S bin or slash UUSR S bin because they're more system specific and as
opposed to general user commands or more for administration now in the boot
grub directory typical files that you will find in there are a menu dot list or
mm menu dot lst which is a general configuration file and it holds the
definitions for the operating systems that you're going to boot additionally
what you will find in there are the stage files for grub now grub boots itself
with at least two stage files the first stage one file is simply put in the
master boot record or boot sector of the partition that you have installed grub
on the purpose of stage one is to load either stage 1.5 or stage two essentially
what stage one does is it sets itself up to encode the location of stage 1.5 or
stage two into the master boot record so it can kick it off now stage 1.5
files generally optional but you're going to find them on a Linux
distribution is what grub needs to read a file system you will see an X2
riser file system XFS file system you will see multiple different types of
stages for being able to read a file systems type and stage 1.5 is usually
installed right or pulled in right after the master boot record so stage one
kicks off stage 1.5 if no stage 1.5 is available it tries to just go right for
stage 2 which is the core grub image which will pull off the file system where
grub was installed will pull out what it needs to set up the bootloader and
begin to boot your operating system of choice now a few other files it might
be in there is a default file which specifies the default image or
definition of boot which we'll get to later also you will find in there other
stages like a stage 2 L Torrito and that's used for creating bootable CD
roms a no grub or I'm sorry an NB grub which is a network boot grub image and a
PXC grub which is a network boot image for using pre-boot execution
now we are not going to cover network booting with grub or creating a
bootable CD in this episode today we're kind of you know don't want to make it
too long additionally we're just more interested in regular Linux systems as
a more advanced topic your version of grub that includes
included with your distribution may not be have grub compiled with the network
booting options so we're going to stick with the the basics for today the
plain vanilla grub now as I said you're probably not going to need to
install grub yourself but just keep it in the back of your mind you are two
basic ways to install grub once you have the software install on your system
of course there is the native which is using a grub boot disk
and using a program called grub install right inside of Linux the native
involves creating a grub boot disk and using the grub interface
to set up an install grub now while they consider this the safer way
to install grub the safest way it is also the most difficult way to install grub
and we're not going to go into many details in here suffice to say that if you
really want to find figure out how to do that read the documentation we're
going to talk about the grub install because it's it's easier of course
translates better to describing that and
I've never had a problem running it so it's not that
risky I don't think any more than any other piece of software you're
installing on your system anyway and the grub install essentially you run grub
install and you pass the device name either a Linux device or a grub device
as an option so for instance you was putting grub dash install then space slash
dev slash hda which would install grub into the masterboot record of the
first IDE disk on your system now we're talking about Linux device naming
here not bsd not grub device naming which I'll cover in a minute
but Linux device naming so if you had a scusy drive in there and you want to
install it on the masterboot record or the scusy drive it'd be grub dash install
space slash dev slash sda for your first scusy device or whatever device you want
now additionally if you wanted to put it in the root or boot partition you would
specify to put partition your your root or boot partition is on so it'd be grub
dash install slash dev slash hda one for example which would be the first
partition on hard drive a one all right now you can
optionally specify the grub device now an example of this would be grub dash
install space open parenthesis hd zero closed parenthesis which would be the
first or the masterboot record on the first hard disk
all right now in addition to and I'm going to cover the grub device naming in
just a second but bear with me in addition to running you know specifying the
link the device that you want to install and you may need to specify
where the images are stored for instance grub install
a space dash dash root dash directory equals slash boot slash grub would say
and then a space dash slash dev slash hda would say all right install grub into masterboot record
the root directory for grub is going to be under the slash boot slash
grub directory is that's where you're going to find the images that you need to kick
off to uh to perform the rest of the install
all right now let's get into grub device naming because it's a little different
than what probably most people are probably used to and might throw you at
first as you're reading through the grub documentation
for specifying a device and grub you put the device
inside parentheses okay and you're basically going to be using two types of devices
hard drive hard drives or floppy drives there's also cd drives there too but we're
we're looking at block drives and floppy drives in a sense so the standard naming
convention for any like hard drives scuzzy cd-round drive hard drive flash drive
any drive block device is hd okay so hd plus the number
a comma and then another number okay the first number is the device the second
number is the partition on a device for instance
you have a hard drive in your computer id hard drive or scuzzy hard drive
you want to install grub or you're going to be looking at the first drive
okay it's going to be hd zero inside of parentheses
if you want to look at the first partition it's hd zero comma zero inside of
parentheses now i don't know if you caught this i said the first partition the first
device i gave them both label is zero that's because grub's naming or
numbering starts with zero so zero is the first
device or partition one is the second device or partition and so on
so think of it different than linux naming which does like
hda a alphabetical letter a for first and then
a number for the partition number one hda would be equivalent to hd zero
hda one would be equivalent to hd zero comma zero all right
in addition to that floppy drives follow the same kind of naming convention
generally you're not going to specify a partition on a floppy drive so you're
just looking at like fd zero for floppy drive one fd one
so on now interestingly um there's another way that you can specify a
device and that is using hexadecimal or
decimal number of the bios drive or how it's
specified in the drive for instance on my triple e pc
they have grub setup to look at the device zero x eight zero
and what that means is zero x eight zero is a hard disk just like hd
it's a hard disk one zero x eight one would be hard drive two or hard disk two
and again it does not matter whether we're talking about a flash drive
flash device any block device zero x eight one or zero
um flat floppy drives are just specified with a zero so floppy one is zero
floppy two is one floppy three is two you get the idea
so that is excuse me there that is how use grub does its device naming and it's
important to know that because you need that in the configuration file and you
need that for running the command line um now what's cool about grub again when
we get talking about the command line is it has tab completion so you can
you can use the grub command line to figure out what devices that you have in
a system so if you were to sit down right now okay and you were to open up
the terminal and you were going to fire up grub okay which is now more
more than likely you uh not going to have it in your path because it is in
it is in the uh i believe user s been
directory user s been if you were to fire that up and type in root and hit tab
or open up open up open parentheses hit root open parentheses and tab
and uh it would start to auto fill in for you just like tab completion on the
command line so root open parentheses tab will fill in the devices that are
able to be set as a block device
by the root command it'll show you now for instance when i do it on my
triple e pc root open print space open parentheses tab
it does hd 0 comma 0 same thing as 0 x 8 0
okay that's the flash device that i'm able to boot from on here
now if you're in grub right now uh you want to
just you know hit enter or back space over what you just typed in
and hit quit to get out of the command line uh grub command line okay
now so you got grub installed and you're already to rock and roll with it
and let's talk about the the one configuration file probably the main one
that you might be most interested in and that's the menu.lst file
the menu.lst file the general configuration for grub is where you
specify your operating system definitions similar to lilo grub is set up
with two main sections there's the general selection section at the top
the first part of the file and then there's your
os or your definition section which is the second part of the file
now in the menu.lst again keeping the back of your mind when we're talking about
it's particularly devices and just about anything grub uses 0 as the first
device it definition or whatever one as the second that's important
always start your numbering with 0 work from there
now in the general settings the first section
grub device grub device naming let's say section 0
all right you have the default you have it with different commands you can put
in it for instance you can put in default
and then the default definition to use a boot remember again starts with 0
so if you set default to 0 it looks the first definition default to 1
looks for the second definition okay and so on
you can put a command in there called timeout
timeout is the number of seconds before the default
definition is loaded now if you didn't specify a default or you look in your
grub menu.lst file and don't see a default
in there that just means the default is set to the first
definition 0 definition number 0 so the timeout will show the menu the grub
menu for the specified number of seconds
and if nothing is done no intervention it'll just kick off the boot
process and begin booting that first default
device or i'm sorry definition right there
simple enough just like lilo but it doesn't specify intent of the second
like lilo does it specifies it in a second so keep that in mind too
if you specify a timeout is 50 it's going to wait 50 seconds
not 50 microseconds i believe it's what lilo uses so you
you want to set it to five for five seconds
some other things you can specify in there which we'll get to in a few minutes
is called a fallback fallback definition is used
as a safety gap in case your first definition doesn't work you can specify one
or more fallback definitions which we'll cover in a few minutes
you can change the color of the menu and the text and highlighting with the color
command the color command takes two parameters
the normal and highlight which essentially equates to
foreground and background color now look at you know see the documentation
for the list of colors available but be aware that only eight of the 16
colors that are available can be used for the background
foreground can have any of the 16 colors but the background can only consist of
black blue green cyan red magenta brown or light gray
you cannot have a yellow background i don't know why but you just can't
now you can have a yellow foreground on a green
but you can have a green background foreground on a yellow
that's just the limitation of it but beware of your color choices here so you
don't end up not being able to see anything or puking when you look at it
of course you can always change those on the fly with with the grub command
when you're booting which we'll cover in a few minutes
after the general configuration and the menu.lst file you have the OS
definitions this is where you specify the definitions that
the operating systems that you want to boot
simple enough first line in your OS definition
title so title space equals space and the name of the OS
be descriptive for instance slackware 2.6 0.22
kernel you can have spaces in there
punctuation in there stuff like that this is just an informative title for
now i have seen in specifying in a configuration
i have seen that it is when you specify in the menu.lst i've seen them both
use uh equals like default equals something
or not using an equals so it would be like root and
specifying the root information um it seems kind of arbitrary as to whether
or not you need to specify an equals there or not but just be aware of that
seems you can get away without specifying the equals you might hear me say
equals just for you know making it a little clearer that you're setting the
value of this okay so title is the name
for the definition after title on a new line root
and specify the root partition to boot
now this must conform to the device naming structure okay
for instance root space parenthesis hd 0 comma 0
closed parenthesis is disc 1 partition 1 um just remember that 0 is 1
1 is 2 and so on next line would be kernel and you're going to specify the
full path to the kernel on your root partition now for example online it would
be kernel space slash boot slash in a kernel name now in addition to that
you can pass any other kernel parameters that you want to at this point
just like in lilo you can specify specific kernel parameters this is where you
would add them to the line right after the kernel image
following the kernel image you're probably going to want to have your in-it
rd or your initializing ram disk image so it's in-it-rd space then the path to
in-it-rd image example in-it-rd space slash boot slash
in-it-rmfs-eepc.img for the in-it-rmd image
that's simple that's all you need after that at which point
you can boot just about any Linux system using those commands
now there's another option that you might need in there for different operating
systems which is the chain loader it loads a file has a
chain loader and then she used primarily for non-multiboot operating
systems like windows or dots or operating systems with faulty bootloaders
like SCO's system set or SCO Unix 7 yeah crap I forget the name of it anyway
we'll cover chain loading in a few minutes but title root kernel in-it-rd
essentially that's all you need okay so you got your menu.list
you got everything set up grew grubs installed and again
I recommend installing it in a masterboot record like Lilo unless you have
certain you know requirements or or species you know that meet your
cases I've never had a problem installing a bootloader in a masterboot record
contrary to how many people or how much documentation will hem and haun say
oh it's risky risky you might not want to do this I've never had a problem
I think it's the easiest way to go especially when you're using a bootloader
of the God's Grub what else could you want
I think what really makes Grub cool I discovered a lot of the other bootloaders
I've used is when you're using it on boot when you booted up
more than likely most systems you're going to come right into the grub menu
is going to list your OS definitions and I'll give you some other text in there
like you know highlighted definition using in the arrow keys
and press e if you want to you know enter if you want a boot e if you want to
edit or press c for the command line now as you do that
so simple enough let's talk about
editing an item in the list in the menu list okay so you boot up grub
your your definitions right there your your OS
you click the e button you are going to be presented with the syntax for that
definition you can then proceed to edit any one of those lines by
moving the arrow key and pressing the e button
to edit that line you'll be given all that line
and you can use basic batch movement on their control b
to go to the front line control e to the end of the line and so forth you use the arrow keys to move back and forth
you can add stuff delete stuff on that line and when you're finished you simply press enter
and it writes back there now let's say you wanted to add an additional line
you go through the line above the line you want to add
where you want to add the new line and you press the okay and it's going to add another
line after the current line that you're on so you want to delete a line
okay you're on a line press the d and it will delete the line
now when you're finished with all your changes you simply press the b button to boot that
definition now say you don't want to keep your changes that's fine too hit the escape
button and it's going to return you back to the menu and ignore all the changes that you made
you're good to go now the next thing that you could do
aside from editing a definition is going to the command line mode
now command line mode is the same thing as the grub command line mode when you're in your operating
system and typing grub you could do some really cool stuff on here you can uh
this is where you will be taken to if you boot grub without a menu.lst file
and you can specify all the exact commands that you find in
ammenu.lst file on the command mode and a whole bunch more in the command mode which is entered
by hitting c at the menu list or if you don't have a menu list defined you type c
and it will bring you in command mode and you can type help and it'll list all the commands
that you you want to do and what what command line mode allows you to do in there is like
yeah allows you to in a sense you know write your own
definition if you really wanted to undo some other stuff you can browse your file system so
long as it can recognize the file systems that you want to browse it has a stage files for it
for instance to browse my my root file system which is on on the first hard drive which is
a scusy drive on my laptop because it's a say to drive sd1
sda partition one i would type root space open parenthesis 0 comma 0 close parenthesis
and it enter at which point then i can use the cat command can catenate or to cd to change
directories and i can move into that file system which is really cool and then i can cat files in
there and i can view the entire contents of the file system tech files and every text files
and everything just by you know mounting attempting to mount these partitions and moving into them
through grubs command line interface you might say oh my god what about security and you know
that means anybody can look at the contents of the file and yeah but we'll talk about some of
the things you could do to protect from that happening okay so the command line is really cool
if you're any command line you can press escape key to return back to the menu just like you
couldn't edit mode now what's cool about these capabilities is let's say you screw up
and you messed up your boot process if you're using arch Linux and you're using lilo and you
boot your system and you forgot to run lilo after you update the kernel you're kind of screwed
all right you can end up with an unbeatable system let's say you're testing a kernel out and you
you add another definition you want to boot that kernel and you messed up on the syntax you can
easily correct it on the command line right there through the edit mode or through the command line
mode and you're back up to running again in in no time it's not as limited as lilo whereas if you
screw something up you better have a boot disk candy or a rescue CD because you're going back
back to the end of the bus jack starting all over again anyway that's handiness
of grub right there as a rescue situation when you screw up on that note I always recommend having
a backup kernel whatever boot loader you use that you know will work and that is good and we're
going to cover that in a few minutes to some other things that you could do but keep that in the
back of your mind you know because if you upgrade somewhere messing around always have a kernel
that you know you can boot and it works right anyway because of the power and capabilities of grub
allowing you to access your file system you might want to save yourself how am I going to
protect my file system or protects you know from people snooping around well grub does offer
some password protection in there and you have two possibilities of protecting you have one is
protection from editing or entering the command line mode on two is protection from booting you
can prevent them from being able to boot a definition or all definitions for that matter unless it
provides a password protecting from editing what you need to do is you need to use the password
command in your in your menu list in the general section of the configuration you put in the password
you put the word password and then either the password in plaintext or the MD5 hash of the
password and in addition to that you can specify a configuration file to load as like an admin
configuration file in addition to the standard configuration file so if they type in the correct
password it would load a different configuration file with different options that they have in there
anyway grub provides you an easy way to convert your password into an MD5 hash
if you type in on your command line or in the terminal grub dash MD5 dash crypt it will ask you
for a password you know just like using the password command you type in your password it'll ask
you for it again it'll type it in an output an MD5 hashed version of that password
additionally you can you can just type MD5 crypt from the grub command line to get the MD5 version
of the password very simple um you add that to the general configuration file then when they
when you boot the system up and if they want to edit the command line mode or
edit mode they have to provide they have to first hit the p key and it's your prompted for the
password enter the password and then it'll let them in if they don't enter the right password
and no no no entry no lucky lucky they're locked out additionally you can prevent people from
booting certain definitions are all definitions by adding the word lock to each after each title
of the definition that's it you have to set it up like you're you're editing for the command line
or you know you have to put the password in the general configuration but you put lock down after
the title in each definition and if they try or an attempt to boot that definition they will be
prompted to enter the password first okay now let's talk about some fallbacks here and stuff
like that that you can secure yourself when you're doing some testing of kernels that you've
compiled yourself or or or whatever you're doing um you can do a boot once only which will attempt
to boot the system using a different definition that you specify and if it fails it will fall back
to your default specification that's simple it's good for testing a kernel and uh what you do is
you add this line to the general configuration section of the menu dot lst you add default space
saved now that tells grub to read a file called default in the uh slash boot slash grub directory
which specifies what definite definition uh to use to boot for the first time okay now you
add your new definition after your good definition and after the good definition before the new one
the last line that you add after uh you know everything to boot is save default all one word
s-a-v-e-d-e-f-a-u-l-t then after the new test definition you add the line saved default s-a-v-e-e-d-e-e-f-a-u-l-t all
one word space zero now what that does is when you boot the first definition it saves that definition
list the zero what it is to the default file under boot slash boot slash grub default it saves zero
because it's zero the first definition um if you boot the first definite or the uh first
definition the test one okay what that does because this is a boot only is it attempts to boot that
and it writes right directly after it attempts as it's tempting to boot it writes that file
save default to default file zero so that the next time grub runs it attempts the boot
it looks at the save default and boots the first or good definition on here okay so if
something happens and it doesn't boot properly uh you can reboot the machine and it would just
automatically put you back into your main one um by default again remember zero is one any other
numbers is is one less so zero is one one is two so forth now after you're done editing your menu
dials t file you save it then you need to run this command on the command line uh slash s bin slash
grub dash set dash default space one now that puts a one in the uh boot grub boot slash grub slash
default file tells that when grub goes to boot next time to try and boot the first definition
automatically the second you know save sorry second definition not the first one definition
number one second definition when that runs it sets the default back to zero afterwards and
that way you can get right back in your system no problem because you have a good definition now
you have the option of providing fallback definitions to grub fallback definitions will keep
trying to boot the fallbacks in succession until one is successful once it finds a successful
one it's going to save that to the default file what what definition that is so every time after
there it will just boot the successful one until you go back and fix it so like the the um
boot once only use you're gonna still need to put in the uh save save or i'm sorry default space
saved in the general configuration then after that you specify the line fallback all one word
f-a-l-l-b-a-c-k space and then each fallback definition that you want to use uh with the space
after them so like fallback space one space two would go fallback definition two then the
definition three if the first default definition fails uh it will try one if that succeeds it will
it will boot uh the second definition it will then try the third definition of the second
definition fails uh and then after each definition that you specify you provide the line you
had the line save default space fallback so it's save default all one word space fallback all
one word so what happens then is it will try each uh definition you have specified in the fallback
once it finds one that will boot successfully it'll save that um that definition you know the
fallback it'll save the next number or the next number if it wasn't successful it'll keep going
to the next one okay uh it will system will try each fallback in succession until successful
boot then save the successful um successful one to the default file simple enough now
neither one of these sections is going to help solve a problem of where the concurrent
actually does boot but fails after that like for instance you didn't
provide it in an RD file so it can't find or read the uh partition file system partition where
your root partition is you can't read that partition uh that's not going to help you out here okay
you're still going to end up you know to grub is successfully booted the or kernel and that's
all that it does um in such a case again you might need to remember you should have a fallback
default kernel that you can boot to that works that's successful so in your list of fallbacks
you know you might have to manually go down and specify that one backup kernel that you have
that always works because your other kernels may fall back to a success but fail during a boot
process understand what I'm saying Jack of course you do because you're smart if you want smart you
wouldn't be listening I want to wrap this up by covering some additional commands that you can
use in the menu list or command line or editing mode um when I talk about a command I'll explain
briefly what it does I'll tell you where it can be used uh the hidden command that is specified
in the menu you can specify in the command but you know I don't know why you really want to what
what the hidden command does is it hides the grub menu unless the escape key is pressed during the
timeout phase so when your system tries to start the boot day if you provide provide the command hidden
in there it will hide the grub menu so you won't see anything even though it does exist you'd
have to press the escape key to get to it the hide command is in the general section you would actually
I'm sorry you would hide in the uh definition section uh you would hide a partition from booting
from the booting OS now this is primarily only useful for DOS or Windows you would hide and then
the device name of the partition you want to hide like for instance if you had a primary partition
that had Linux installed and then your second primary partition had Windows installed
you would hide the first primary partition from Windows so that it would think it's on the primary
partition because Windows and DOS want to be on the primary partition first primary partition
subsequently you can use the unhide command to unhide a partition that's used in the menu
you can use them on a command line too if you're booting from command or in the edit mode
boot is basically used for command line or editing a menu entry you would type in boot and it would
attempt to boot everything that you have specified the cat command is primarily used in the command line
mode which will list the contents of a file so as I said before you can browse to a file on the
file system on a partition and type in cat for instance cat slash atc slash fstab which will
your fstab file uh chain loader I briefly mentioned chain loader when booting other operating
systems chain loader loads a file as a chain loader and it can use the block list notation now
block list notation block list is a file that does not appear in the file system
an example of this is like the windows bootloader would appear in the block the block one of the
device not block zero which is the master boot record but might appear in block one so you
would specify to the chain loader uh chain loader space plus one when you're trying to boot the
operating system windows and it would try to load the file in the first block of the partition
block number one actually not block zero but block number one and hopefully it will work it's
used for um oh s's with a defective bootloader or for booting windows and dots which
maybe they have a defective bootloader too I don't know fine command is uh pretty simple
fine command will start shooting uh fine and then the name of the file you want found will search
for the file in all the mountable partitions uh just like a regular file command and it will
display the full path to the file that it finds halt command is using command line mode is used
to halt the system uh again I have briefly mentioned help which will display a list of all the
commands and if you type in help in the command name will display the list for that help file
pause is uh used in the menu it you can provide some text after the pause and it would display that
text and will wait for a prompt from the user to press any key to continue on you wouldn't really
use that in command or edit mode it would make any sense uh quit is using command line mode quit will
exit the command line or edit mode and go back to the main menu mode uh reboot is used in the command
line mode again which will reboot the system um now the root command which I briefly mentioned
before it will set the device to root and attempt the mount and get the information of the device
so if you type in root space uh parenthesis hb hd 0 comma 0 it will attempt to set the root
device to the first partition on the first drive and then you can cd into it or cat into it by
specifying the device device and then slash in the path uh you could also use the uh no you can
use the command root no verify all one word which will attempt the mount the root to uh it will
set the root device but not attempt to mount it well I hope that this little introduction to grub
has been informative so the next time you are uh booting your Linux machine because it's a laptop
and you didn't want to waste the battery transporting it to work because you know Linux machines
don't really need to be rebooted that much and if you're rebooting it on a regular basis
god ask yourself why anyway so you're booting you know your system and you pop up to the grub
menu take a minute to pause and stop and check it out and see what you can do and have fun with it
uh unless you know you know you read these commands that we're talking about your chances are
you're not going to break anything but you're going to have learned something new and have fun
doing it as always remember hacker public radio is community sponsor community driven if you are
interested in educating people on a subject that you're pretty familiar with or you want to learn
to subject you're not familiar with and then educate people get in touch with uh the hacker public
radio crew off the website and uh you know make an episode or two we're always looking for people
and uh if you have any questions comments you can send your email to dan d a n n at the linuxlink.net
or i'll check out the comment section for this episode i thank you very much i hope to have a
next another episode out very soon uh i think the next one is going to talk about options that you
can pass to the kernel when you're booting or who the hell knows what it will be but uh it'll be
something to do with the linux boot up and start a process again thank you very much and you have a
wonderful happy hacking day. Thank you for listening to hacker public radio
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