Linux LPI 117-101 # 2 Of 9

System boots in Default Runlevel defined in /etc/inittab file.
id:3:initdefault:
After booting the system we can switch from one runlevel to another by using the init
runlevel command.

dmesg command helps users to print out their bootup messages.

First SCSI disk device is filename is /dev/sda and second /dev/sdb.

runlevel -- find the current and previous system runlevel.
It means currently system running on runlevel 3 and not switched to any runlevel.

Open source software is that software, which is freely available to
download from the Internet with source code and no restriction to modify,
redistribute the software. So, Linux is the Open source OS.

make install command install the program on proper directory by
reading the Makefile for program relationships.

Explanation: /etc/profile is the global login scripts, parsed by all users with
Borune-style shells including bash and sh. Usually used to set the default path,
values assign on variable, startup program execution.
Sample /etc/profile Configuration
# /etc/profile
# System wide environment and startup programs, for login setup
# Functions and aliases go in /etc/bashrc
pathmunge () {
if ! echo $PATH | /bin/egrep -q "(^|:)$1($|:)" ; then
if [ "$2" = "after" ] ; then
PATH=$PATH:$1
else
PATH=$1:$PATH
fi
fi
}
# Path manipulation
if [ `id -u` = 0 ]; then
pathmunge /sbin
pathmunge /usr/sbin
pathmunge /usr/local/sbin
fi
pathmunge /usr/X11R6/bin after
# No core files by default
ulimit -S -c 0 > /dev/null 2>&1
USER="`id -un`"
LOGNAME=$USER
MAIL="/var/spool/mail/$USER"
HOSTNAME=`/bin/hostname`
HISTSIZE=1000
if [ -z "$INPUTRC" -a ! -f "$HOME/.inputrc" ]; then
INPUTRC=/etc/inputrc
fi
export PATH USER LOGNAME MAIL HOSTNAME HISTSIZE INPUTRC
for i in /etc/profile.d/*.sh ; do
if [ -r "$i" ]; then
. $i
fi
done
unset i
unset pathmunge

The easiest journaling file system to convert the ext2 partition to without destroying existing data would be ext3. Ext3 is a journaling file system that is backward compatible with ext2, meaning it can be easily converted from ext2 without losing any data. It provides the benefits of journaling, which helps improve system reliability and recovery in case of power failures or system crashes.

Single user mode is used for Troubleshooting and maintenance of System boot problem. So, s or S or single or 1 runlevel is called the administration mode.

What are the advantages of ext3?
Why do you want to migrate from ext2 to ext3? Four main reasons: availability, data
integrity, speed, and easy transition.
Availability
After an unclean system shutdown (unexpected power failure, system crash), each ext2
file system cannot be mounted until its consistency has been checked by the e2fsck
program. The amount of time that the e2fsck program takes is determined primarily by
the size of the file system, and for today's relatively large (many tens of gigabytes) file
systems, this takes a long time. Also, the more files you have on the file system, the
longer the consistency check takes. File systems that are several hundreds of gigabytes in
size may take an hour or more to check. This severely limits availability.
By contrast, ext3 does not require a file system check, even after an unclean system
shutdown, except for certain rare hardware failure cases (e.g. hard drive failures). This is
because the data is written to disk in such a way that the file system is always consistent.
The time to recover an ext3 file system after an unclean system shutdown does not
depend on the size of the file system or the number of files; rather, it depends on the size
of the "journal" used to maintain consistency. The default journal size takes about a
second to recover (depending on the speed of the hardware).
Data Integrity
Using the ext3 file system can provide stronger guarantees about data integrity in case of
an unclean system shutdown. You choose the type and level of protection that your data
receives. You can choose to keep the file system consistent, but allow for damage to data
on the file system in the case of unclean system shutdown; this can give a modest speed
up under some but not all circumstances. Alternatively, you can choose to ensure that the
data is consistent with the state of the file system; this means that you will never see
garbage data in recently-written files after a crash. The safe choice, keeping the data
consistent with the state of the file system, is the default.
Speed
Despite writing some data more than once, ext3 is often faster (higher throughput) than
ext2 because ext3's journaling optimizes hard drive head motion. You can choose from
three journaling modes to optimize speed, optionally choosing to trade off some data
integrity.
1. One mode, data=writeback, limits the data integrity guarantees, allowing old data to
show up in files after a crash, for a potential increase in speed under some circumstances.
(This mode, which is the default journaling mode for most journaling file systems,
essentially provides the more limited data integrity guarantees of the ext2 file system and
merely avoids the long file system check at boot time.)
2. The second mode, data=ordered (the default mode), guarantees that the data is
consistent with the file system; recently-written files will never show up with garbage
contents after a crash.
3. The last mode,
data=journal, requires a larger journal for reasonable speed in most cases and therefore
takes longer to recover in case of unclean shutdown, but is sometimes faster for certain
database operations.
The default mode is recommended for general-purpose computing needs. To change the
mode, add the data=something option to the mount options for that file system in the
/etc/fstab file, as documented in the mount man page (man mount).
Easy Transition
It is easy to change from ext2 to ext3 and gain the benefits of a robust journaling file
system, without reformatting. That's right, there is no need to do a long, tedious, and
error-prone backup-reformat-restore operation in order to experience the advantages of
ext3. There are two ways to perform the transition:
1. The Red Hat Linux installation program offers to transition your file systems when
you upgrade your system. All you have to do is select one checkbox per file system.
The tune2fs program can add a journal to an existing ext2 file system. If the file system is
already mounted while it is being transitioned, the journal will be visible as the file
.journal in the root directory of the file system. If the file system is not mounted, the
journal will be hidden and will not appear in the file system. Just run tune2fs -j /dev/hda1
(or whatever device holds the file system you are transitioning) and change ext2 to ext3
on the matching lines in /etc/fstab. If you are transitioning your root file system, you will
have to use an initrd to boot. Run the mkinitrd program as described in the manual and
make sure that your LILO or GRUB configuration loads the initrd. (If you fail to make
that change, the system will still boot, but the root file system will be mounted as ext2
instead of ext3 - you can tell this by looking at the output of the command cat
/proc/mounts.) More information on tune2fs can be found in the tune2fs man page (man
tune2fs).

Harddisk Recognization
Primary Master /dev/hda
Primary Slave /dev/hdb
Secondary Master /dev/hdc
Secondary Slave /dev/hdd
According To QUESTION, drive is secondary master, then device name is /dev/hdc and
Logical partition start from 5.
So /dev/hdc5

System boots in Default Runlevel defined in /etc/inittab file.
id:3:initdefault:
After booting the system we can switch from one runlevel to another by using the init
runlevel command.

Runlevel 6 is called reboot. To switch runlevel 6: init 6

Runlevel 0 is called Halt
To switch runlevel 0:
init 0

Standard Runlevel
0 - halt
1 or s or single or S- Single user mode
2 - Multiuser, without NFS (The same as 3, if you do not have networking)
3 - Full multiuser mode
4 - unused
5 - X11
6 - reboot (Do NOT set initdefault to this)
To boot the kernel parameter from lilo bootloader, press ctrl+x and then kernel name runlevel. Example to boot linux system on runlevel 3: linux 3

Harddisk Recognization
Primary Master /dev/hda
Primary Slave /dev/hdb
Secondary Master /dev/hdc
Secondary Slave /dev/hdd
According To question, Device name is /dev/hdb and paratition number is 3.
/dev/hdb3

Explanation:
0 - halt (Do NOT set initdefault to this)
1 - Single user mode
2 - Multiuser, without NFS (The same as 3, if you do not have networking)
3 - Full multiuser mode
4 - unused
5 - X11
6 - reboot (Do NOT set initdefault to this)
Runlevel 3 is called full multi user and Runelvel 5 is called X Window System

When we install, most of the user's commands, administrative commands and
applications are installed on /usr by creating sub directories ie /usr/bin, /usr/sbin. So we
required more space then other partitions.

A Symbolic link points to another file and the contents of link file is referenced file. So, symbolic linked file occupied the very less space the original file.

Generally in one System we can connect four Physical Harddisks. As a
Primary Master, Primary Slave, Secondary Master, Secondary Slave.
In One System: Either four Primary partitions or 1 Primary or 2 Primary or 3 Primary + 1
extended and all logical partitions will be create under extended partations.
Hardisk device recognized as follows
Primary Master : /dev/hda
Primary Slave : /dev/hdb
Secondary Master : /dev/hdc
Secondary Slave : /dev/hdd
Suppose you have only single harddisk and going to install Linux, Maximum you can
create 4 primary partitions. If you create four primary partitions you can't create extended
partitions that mean no logical partitions can create.

-d delay
If you have specified several kernels, and press Shift at boot time, the boot loader will
present you with a choice of which system to boot. After a timeout period the first kernel
in the list is booted. This option specifies the timeout delay in deciseconds.
Example: lilo -d 50

/home is called typical user's home directory. All user's home directory will be created on /home. So, it should own mount point.

which and whereis command displays the executable path of
commands. Example: which clearàShows actually where clear is stored similarly
whereis clear.

The Convention for swap partition is Double of Physical RAM size.

0 - halt (Do NOT set initdefault to this)
1 - Single user mode
2 - Multiuser, without NFS (The same as 3, if you do not have networking)
3 - Full multiuser mode
4 - unused
5 - X11
6 - reboot (Do NOT set initdefault to this)
Runlevel 2 is called the multi user without NFS ( Not Networking services available).

lilo command installs the bootloader on MBR (Master Boot Record) and activated on next boot time.

make install command install the program on proper directory by reading the Makefile for program relationships.

Swap also called the virtual memory, we should give the swap space as
double of RAM size.

Here is the sample Configuration
prompt
timeout=20
default=linux
boot=/dev/hda
map=/boot/map
install=/boot/boot.b
message=/boot/message
linear
image=/boot/vmlinuz-2.6.9-5.EL
label=linux
initrd=/boot/initrd-2.6.9-5.EL.img
read-only à Mounts the root filesystem on read only mode
append="rhgb quiet root=LABEL=/"

This standard enables:

1. Software to predict the location of installed files and directories, and

2. Users to predict the location of installed files and directories.

This is done by:

1. Specifying guiding principles for each area of the filesystem,

2. Specifying the minimum files and directories required,

3. Enumerating exceptions to the principles, and

4. Enumerating specific cases where there has been historical conflict.

. means current directory and .. means parent directory. ./ represents
under the current directory. configure command is used to check the error, system
specific configuration information.

The /var/spool/mail directory contains the spooling mail. Under
/var/mail/spool file with same as username are here, which contains the user's spooling mail.

Backup and Restore depends on the importance of data, the /usr, /etc,
/home contains the importance data then /tmp and /swap. /usr/bin, /bin contains all
user commands, /usr/sbin, /sbin contains the administrative commands, /etc/
contains the configuration files. So these directory contains the important files.

Specify the percentage of the filesystem blocks reserved for the super-user. This value defaults to 5%. If you want to change the percentage for super user: mke2fs -m percentage partition

Whereis - locate the binary, source, and manual page files for a
command
Syntax: whereis [options] command
Options:
-b à Search only for binaries
-m à Search only for manual section
-s à Search only for sources.

make install command creates/writes the files or directory on different
directory. To write or to create user required write permission to parent directory.
Generally, normal users doesn't have write permission to system directory.

md5sum - compute and check MD5 message digest.

Not being able to use new, big harddrives is usually connected to the
BIOS in the computer.

If size to boot partitions assigns after the 1024 cylinder then, lilo boot
loader unable to load the kernel so it effects to boot partaiton. If you are using the
LILO boot loader boot partitions should be within 1024 cylinder.

-R command line
This option sets the default command for the boot loader the next time it executes. The
boot loader will then erase this line: this is a once-only command. It is typically used in
reboot scripts, just before calling shutdown -ra.

Before start to installation, carefully reads all documentation of the
specific source code, then check where dependencies are there ? dependencies are
already installed or with there identify and install.

According to the technical information available at Linux From Scratch Ver 3.0, Before we can build our new Linux system, we need to have an
empty Linux partition on which we can build our new system. I recommend a partition size of at least 750 MB. This gives enough space to store all the tarballs
and to compile all packages without worrying about running out of the necessary
temporary disk space. But you probably want more space than that if you plan to
use the LFS system as your primary Linux system.

The Linux /proc Directory is a Virtual Filesystem provided by linux kernel. /proc
contains files and directories that let system administrators and programmers access
system information.
If you misconfigured the bootloader, you can't load the Linux. We have different Boot
loader like lilo, grub etc. If you try to load the Linux using misconfigured bootloader you


will get kernel panic, no init found or Kernel Panic - Not Suyncing: Attempt to kill init
etc Error. At this time you can boot the system by passing different parameters from the
bootloader. If you are using LILO bootloader press ctrl+x, If you are using grub, press a
or e and edit or pass the different parameter.
Before passing kernel parameter, you should know what to pass, the file /proc/cmdline
contains the parameter can pass from bootloader.
For Grub
Contains of /proc/cmdline
ro root=LABEL=/ rhgb queit
or
/proc/cmdline
ro root=/dev/hda2
This file shows the parameters passed to the kernel at the time it is started.This tells us
that the kernel is mounted read-only (signi_ed by (ro)) off of the second partition on the
first IDE device (/dev/hda2).
For LILO
BOOT_IMAGE=linux ro BOOT_FILE=/boot/vmlinuz-2.6.9-5.EL rhgb quiet
root=LABEL=/1

-d delay
If you have specified several kernels, and press Shift at boot time, the boot loader will
present you with a choice of which system to boot. After a timeout period the first kernel
in the list is booted. This option specifies the timeout delay in deciseconds.
Sample Configuration of /etc/lilo.conf
prompt
timeout=20
default=linux
boot=/dev/hda
map=/boot/map
install=/boot/boot.b
message=/boot/message
linear
image=/boot/vmlinuz-2.6.9-5.EL
label=linux
initrd=/boot/initrd-2.6.9-5.EL.img
read-only
append="rhgb quiet root=LABEL=/"

vga=mode
This specifies the VGA text mode that should be selected when booting. The following
values are recognized (case is ignored):
normal: select normal 80x25 text mode.
extended (or ext): select 80x50 text mode.
ask: stop and ask for user input (at boot time).
: use the corresponding text mode. A list of available
modes can be obtained by booting with vga=ask and pressing
[Enter].

To boot the system in runlevel 5 we should specify the id:5:initdefault:
in /etc/inittab file. By passing kernel arguments from boot loader we can override
the specified runlevel in /etc/inittab. If default runlevel is not specified, system boots
on runlevel 9(unknown runlevel).

To find differences between archive and file system we can use -d or --diff or -compare option.
Sysntax: tar [option] archivefile1 archivefile2

when we install the binaries files, it creates the files, directories into the directory. To write the files or directories, there should be the write permission.
Before examine the Directory permission.
ls -ld directoryname
drwxr-xr-x

Here is the sample Configuration
prompt
timeout=20
default=linux
boot=/dev/hda
map=/boot/map
install=/boot/boot.b
message=/boot/message
linear
image=/boot/vmlinuz-2.6.9-5.EL
label=linux
initrd=/boot/initrd-2.6.9-5.EL.img
read-only
append="rhgb quiet root=LABEL=/" à Here specifying the root partation

hd0 Primary Master hda
hd1 Primary Slave hdb
hd2 Secondary Master hdc
hd3 Secondary Slave hdd
Similarly partition number starts from 0 like array index in programming.