Redhat Linux Basics

8/21/2019 Redhat Linux Basics

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Prepared by : Date : Page Number : 1

Prepared by : Ashish TyagiDivision : GIS

Team : Motorola


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Prepared by : Your name Date : Page Number : 2

Training Agenda

Conclusion (Post Quiz,

Review of

Expectations, Feedback)

System Initialization

and shutdown process

Basic System

Configuration Tools

Lunch Break

Bash Shell, Text Processing

and Vi

Users & Groups

Tea Break

File system Basics

Introduction to Linux

(Expectations, Pre-Quiz)

DAY 1

Network Configuration12:30-13:00

Lunch Break13:00-14:00

Filesystem Management11:45-12:30

Tea Break11:30-11:45

NFS, FTP,Troubleshooting15:45-17:30

Installation14:00-15:45

Recap of Day 1,

Package Management

10:00-10:30

Conclusion (Post Quiz, Review

of

Expectations, Feedback)

17:30-18:00

System Services and kernelmodules10:30-11:30

Day 2Start times


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Purpose

To understand Linux Basics


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Program Objectives

At the end of this course, you will be able to:

Understand Basics of RedHat Enterprise Linux Manage a Linux based system


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Ground Rules

In order to ensure the productivity of our training, we willneed to be.

- Punctual..

- Put mobile on vibration and do not receive calls within thetraining room..

- Not dropout from the training withoutpermission..

- Be more interactive.


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CONTENTS

LESSON 1 Linux BasicsLESSON 2 File system Basics

LESSON 3 Users & Groups

LESSON 4 Bash Shell

LESSON 5 Text Processing and Vi

LESSON 6 Basic System Configuration Tools

LESSON 7 System Initialization and shutdown process

LESSON 8 System Services and kernel modules

LESSON 9 Package Management

LESSON 10 File system Management


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Contents

LESSON 11 Network Configuration

LESSON 12 Installation

LESSON 13 NFS & FTP

LESSON 14 Troubleshooting


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Linux Basics

Lesson 1


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Lesson Objectives

Linux Basics

At the end of this lesson, you will be able to

Understand Linux Basics


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Linux Origins

1984: The GNU Project and the Free Software Foundation

Creates open source version of UNIX utilities

Creates the General Public License (GPL)

1991: Linus Torvalds creates open source, UNIX-like kernel,

released under the GPL

Ports some GNU utilities, solicits assistance online


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Different Distributions

Linux distributions are OS based on the Linux kernel Red Hat Enterprise Linux

Suse Linux

Fedora (Open Source project supported by RedHat)


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Linux principles

Everything is a file (including hardware) Small, single-purpose programs

We can chain programs together to perform complextasks

Configuration data stored in text files


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Logging in to a Linux System

Two types of logins are possible text-based and graphicallogins

By default Linux system run six virtual consoles and onegraphical console

Server systems often have only virtual consoles Desktops and workstations typically have both

You can Switch among virtual consoles by typing: Ctrl-Alt-F[1-6]

To Access the graphical console Press Ctrl-Alt-F7

Login name and password is required to access

Each user has a home directory for personal file storage


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The X Window System is Linux's graphical subsystem

Xorg is the particular version of the X Window System usedby Red Hat

Look and behavior depends on the desktop environment used

Two desktop environments are provided by Red Hat

GNOME and KDE Log into a virtual console and run startxto manually start

The X server appears on Ctrl-Alt-F7


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The root user

The root user is a special administrative account,also called the superuser

root has allmost complete control over the system

Do not login as root unless necessary

Normal (unprivileged) users' potential to do damage ismore limited

Sucan be used to switch to root user as required.

sudo commandruns commandas root idshows information on the current user


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Running Commands

Commands have the following syntax:command opt ionsarguments

Each item is separated by a space

Options modify a command's behavior Single-letter options usually preceded by -

Can be passed as -x -y -zor -xvz

Full-word options usually preceded by --

EX. --help


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Getting Help on commands

man and info pages can be used to get help oncommands

man date : will show a help page on date command

info date : will provide more details on command

command--helporh

/usr/share/doc/ directory contains good documentsfor some commands.


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File system Basics

Lesson 2


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File system Basics

Files and directories are organized into a single-

rooted tree structure File system Hierarchy begins at the rootdirectory,

represented by / character.

Names are case-sensitive

Paths are delimited by / Each shell and system process has a current

working directory(cwd), which is shown bypwdcommand

Names may be up to 255 characters


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All characters are valid, except the forward-slash Absolute pathnames Begins with a forward slash

Relative pathnames do not begin with a slash andspecify location relative to your current workingdirectory


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Some Important Directories

Home Directories: /root,/home/username

User Executables: /bin, /usr/bin, /usr/local/bin

System Executables: /sbin, /usr/sbin, /usr/local/sbin

Other Mount points: /media, /mnt

Configuration: /etc Temporary Files: /tmp, /var/tmp

Log files: /var/log/

Kernels and Boot loader: /boot

System Information: /proc, /sys Libraries: /lib, /usr/lib, /usr/local/lib


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Some Commands

cdchanges directoriescd/home/

To a directory one level up

cd..

To your home directory

Cd ls can be used to list the directory contents.

-l, -ld, -a

cpcopy files and directories

cp file1 file2 destination

-r, -f, -v

mv moves files and directories from one location to other

mv file destination


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touch- create empty files or update file timestamps

rm- remove files

rm [options]

-r, -f, -v, -i

mkdircreates directories

rmdirremoves empty directories rm -rrecursively removes directory trees

Determining File Content

file


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Hard Links

A hard link adds an additional pathname to referencea single file One physical file on the file system

Each directory references the same inode number

Increments the link count The rmcommand decrements the link count File exists as long as at least one link remains

When the link count is zero, the file is removed

Cannot span drives or partitions

Syntax: ln f i lename[l inkname]


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Symbolic or Soft Links

A symbolic link points to another file ls -ldisplays the link name and the referenced file

lrwxrwxrwx 1 u1 u1 11 Sep 25 18:02 sl -> /etc/passwd

lfor symbolic link

Syntax:

ln -s filename l inkname


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Users and groups

Lesson 3


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Users and groups

Every user is assigned a unique User ID number (UID)UID 0 identifies root

Users' names and UIDs are stored in /etc/passwd

Users are assigned a home directory and a shell

Users cannot read, write or execute each others' files withoutpermission

Users are assigned to groups

Each group is assigned a unique Group ID number (gid)

GIDs are stored in /etc/group


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Each user is given their own private group Can be added to other groups for additional access

All users in a group can share files that belong to the group

User names are case sensitive To add a new user

useradd options

Options are

-dhome_dir-ccomment

-ginitial_group

-G Secondry Group

-muser's home directory will be created if it does not exist.

-sshell


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Groupsare logical expressions of organization, tying userstogether for a common purpose.

Users within the same group can read, write, or execute filesowned by the group.

Groups are assigned GIDs which are stored in /etc/group

To add a group

groupadd options

-g gid

When user accounts are created, a private group is alsocreated with the same name

Users are assigned to this private group

User's new files affiliated with this group


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File Security

Every file is owned by a user and a group If UID matches, userpermissions will apply

if GID matches, grouppermissions will apply

If neither match, otherpermissions will apply

Four symbols are used when displaying permissions:

r: permission to read a file or list a directory's contents

w: permission to write to a file or create and remove files froma directory

x: permission to execute a program or change into a directory

and do a long listing of the directory-: no permission (in place of the r, w, or x)


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File permissions may be viewed using ls -l

$ ls -l /var/log/xyz

-rwxr-xr-x 1 root root 152147 Jan 1 11:30 /var/log/xyz

File type and permissions represented by a 10-character string

Only root can change a file's owner Only root or the owner can change a file's group

Ownership is changed with chown

chown [-R] user_namef i le|directory

Group-Ownership is changed with chgrp chgrp [-R] group_namef i le|directory


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To change permission of a file use chmod command

chmod mode

-R option for recursive mode Where modecan be one of the following:

u for user,g for group and ofor other

+for grant and -for denyr, wor xfor read, write and execute

Examples:

ugo+r: Grant read access to all

o-wx: Deny write and execute to others


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A numeric method can also be used

first digit specifies owner's permissions

second digit specifies group permissions

third digit represents others' permissions

Permission are denoted by

4 (for read)2 (for write)

1 (for execute)

e.g.: chmod 755 datafile.dbf


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Bash Shell

Lesson 4


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What is a shell

a shell is a macro processor that executescommands and provides the user interface to theother commands.

Shells also provide a small set of built-in commands(builtins) implementing functionality impossible orinconvenient to obtain via separate utilities. Forexample, cd, break, continue, and exec)

A shell provides access to the services of a kerneland works as a interface between Kernel and user

programs.


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Bash Shell

There are many shells available for Linux

- sh, csh, ksh, zsh, bash etc. Bash is an acronym for `Bourne-Again SHell'

The Bourne shell is the traditional Unix shell originally writtenby Stephen Bourne. All of the Bourne shell builtin commands

are available in Bash The improvements offered by BASH include:

Command line editing

Unlimited size command history

Job ControlShell Functions and Aliases


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Using Bash Shell

*- matches zero or more characters ?- matches any single character

Type Tabto complete command lines:

For the command name, it will complete a command

nameFor an argument, it will complete a file name

bashstores a history of commands you've entered,which can be used to repeat commands

Use historycommand to see list of "remembered"commands


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Use the upand downkeys to scroll through previouscommands

use Ctrl-rto search for a command in command history. To recall last argument from previous command

Esc .

Alt.

A commands output can be redirected to a file> Redirect STDOUT to file

2> Redirect STDERR to file

&> Redirect all output to file

Pipes (the |character) can connect 2 or more commandscommand1| command2


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Aliases let you create shortcuts to commands

$ alias dir='ls -laF' Use aliasby itself to see all set aliases


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Text processing and Vi editor

Lesson 5


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Text processing

To view file Contents use less, moreand cat/textsearches for text

n/Njumps to the next/previous match

To view some lines from starting or end use headand tail

tailf to read subsequent additions to the fileUse -nto change number of lines displayed

To find a keyword in a file use grep

grep user1 /etc/passwd

Use -ito search case-insensitively


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Use wcto count numbers of lines and word in a file

cat /etc/passwd | wclUse -wfor word count

Use sort to sort contents to STDOUT

sort options file

Common options-rperforms a reverse (descending) sort

-nperforms a numeric sort

-fignores (folds) case of characters in strings

-u(unique) removes duplicate lines in output

Vi Edit


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Vi Editor

Vi is the standard Unix text editor Three main modes:

Command Mode : Move cursor, cut/paste text,change mode

Insert Mode: Modify text

Ex Mode: Save, quit, etc

Escexits current mode

PressingEsc2 times returns to command mode


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To start Vi execute..

vi

If the file exists, the file is opened and the contents aredisplayed

If the file does not exist, viwill create it when the edits aresaved for the first time

ibegins insert mode at the current cursor position

a begins in append mode

Aappend to end of line

Iinsert at beginning of line

oinsert a new line belowOinsert a new line above


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Enter Ex Mode by pressing : in command mode Creates a command prompt at bottom-left of screen

Common write/quit commands::wwrites the file contents to disk

:wqwrites and quits

:q!quits without saving the changes.

To search text in a file/, n for forward search, Nfor backwardsearch

To copy a line press yy, to delete dd, to paste p in

command mode


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Basic System Configuration Tools

Lesson 6

T t t ' D t d Ti f li


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To set system's Date and Time from cli

date [MMDDhhmm[YYYY][.ss]]

To check current date and timedate

To find files based on a pattern:

Locate & Find

Locatequeries a pre-built database of paths to fileson the system. Use updatedbto update thedatabase

locate

-iperforms a case-insensitive search

Use find to find files based on a criteria


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Use find to find files based on a criteria

find [directory...] [criteria...]

Searches directory trees in real-time Slower but more accurate than locate

CWD is used if no starting directory given

Ex. find / -namemyfile.txt

find / -inamemyfile.txtfind /var -useruser2group staff

Criteria are ANDed together by default.

Can be OR'd or negated with -oand -not

find -user joe -o -user jane

A non GUI web browser


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A non GUI web browser

Links http://www.csc.com

wgetcan be used to retrieve files through http and ftp.

wget ftp://example.com/file1.doc

ssh is a Secure replacement for older remote-access toolslike rsh and telnet.

sshl

ssh root@hostname

Scp is Secure replacement for rcp, used to copy files fromone host to onther over ssh

scp sourcedest inat ion

scp /var/users.txt root@hostname:/root

-r can be used to recursively copy directories


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Rsync can also be used to copy files from one hostto another. Faster than scp- copies differences in

like filesrsync/var/users.txt root@hostname:/root

lftpis a cli based ftp client

lftp ftp.csc.com

Sftp provide ftp like access over SSH protocol


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System Initialization and shutdown process

Lesson 7

Boot Sequence Overview


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Boot Sequence Overview

BIOS Initialization Boot Loader

Kernel initialization

initstarts and enters desired run level by executing:

/etc/rc.d/rc.sysinit

/etc/rc.d/rc and /etc/rc.d/rc?.d/

/etc/rc.d/rc.local

X Display Manager if appropriate

Boot Loader Components


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Boot Loader

1st Stage - small, resides in MBR or boot sector

2nd Stage - loaded from boot partition Minimum specifications for Linux:

Label, kernel location, OS root filesystem and location of the initialramdisk (initrd)

GRUB the GRand Unified Bootloader

Command-line interface available at boot prompt Boot from ext2/ext3, ReiserFS, JFS, FAT, minix, or FFS file

systems

Configurtion file is /boot/grub/grub.conf

Changes to grub.conf take effect immediately

If MBR on /dev/hda is corrupted, reinstall the first stage bootloaderwith:

/sbin/grub-install

Boot Process


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Boot Process

Kernel boot time functionsDevice detection

Device driver initialization

Mounts root file system read only

Loads initial process (init)

initreads its configuration file /etc/inittab and startother processes as configured.

Run Levels


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initdefines run levels 0-6, S, emergency The run level is selected by either

the default in /etc/inittab at boot passing an argument from the boot loader using the command init

To check current and previous run levelsrunlevel

Default run level is specifies in /etc/inittabid:3:initdefault

Run level defines which services to start Each run level has a corresponding directory:

/etc/rc.d/rcX.d

The System V init scripts reside in: /etc/rc.d/init.d

Shutting down the system


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Shutting down the system

Use Init 0 to switch to run level 0 Shutdownh now to shut down system immediately

-r to reboot the system

a time can also be given

shutdownh hh:mm to shutdown at aspecific time

shutdownh +m to shutdown after m minutes


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System Services and kernel modules

Lesson 8

What is a Process


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A process is a set of instructions loaded into memory

Numeric Process ID(PID) used for identification UID, GID determines file system access

Normally inherited from the user executing the command

View Process information with pscommand

psef-e shows extended information

-f shows PPID

-u print process owner

Use Top command to see real time process information

Sending Signals to Processes


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Sending Signals to Processes

To send signal by PID

kill [signal] p id

Most common signals are

-1, -HUP send signal to process to reread its configuration file

-9 Kill a process forcefully-15 send signal to process to end it.

Run a process in the background

Append an ampersand to the command line firefox &

Cron


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Cron

Cron is used to schedule process to run at a specifictime.

Crontab entries are saved in a file

Entry consists of five space-delimited fields followedby a command line

One entry per line, no limit to line length

Fields are minute, hour, day of month, month, andday of week

Comment lines begin with # Crontabe to edit crontab.

Managing ServicesC l f d t "S t V" "S V i


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Commonly referred to as "System V" or "SysV services Several configuration files are often used Most services start one or more processes Services are managed by scripts, found in /etc/init.d/

Examples:/etc/init.d/httpd status

service httpd status

Chkconfig command is used to switch on or off a service at aparticular runlevel.Does not modify current run state of System V serviceschkconfig httpd on ( will switch on httpd service in runlevel 2,3,4and 5)Chkconfig --list httpd ( will display current status at different

runlevels)

xinetd Managed Services


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g

Less frequently used services are managed by thexinetdservice

Incoming requests are listened by xinetd

Configuration files: /etc/xinetd.conf,

/etc/xinetd.d/ Services can be controlled with chkconf igcommand

chkconf ig t f tp on

Linux Kernel


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The kernel constitutes the core part of the Linux operating system. It

interacts with hardware and provide resources to application. Some features are

System initialization: detects hardware resources and boots up thesystem.

Process scheduling: determines when processes should run and for howlong.

Memory Management: allocates memory on behalf of running processes.

Security: Constantly verifies filesystem permissions and firewall rules.

Implements standard network protocols and filesystem formats.

Architectures supported are x86, x86_64, IA64/Itanium etc.

Kernels are installed under /boot/vmlinuz-*

Kernel Modules


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Modules are small kernel extensions that may beloaded and unloaded as required

These Can implement drivers, filesystems, firewall,and more

Modules Are located under /lib/modules/$(uname -r)/ Compiled for a specific kernel version and are

provided with the kernel RPM.

Third party modules may be added as perrequirement


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lsmodprovides a list of loaded modules

modprobecan load and unload modules modinfodisplays information about any available

module

/etc/modprobe.conf used for module configuration

The initial RAM disk provides modules loaded earlyin the boot process.

This file is located under /boot/initrd-$(uname -r).img

Hardware Devices


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Files under /dev used to access drivers Block Devices

/dev/hda, /dev/hdc - IDE hard disk, CDROM

/dev/sda, /dev/sdb - SCSI, SATA, or USB Storage

/dev/md0, /dev/md1 - Software RAID Character Devices

/dev/tty[0-6] - virtual consoles

/dev/null, /dev/zero - software Devices

/dev/random, /dev/urandom - random Numbers

Kernel Configuration using /proc


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g g

/proc is a virtual file system which contains informationregarding running system.

Any modification is not persistent across reboot

It can be used to display process information, memoryresources, hardware devices, kernel memory, etc

Can be used to modify network and memory subsystems ormodify kernel features

Modifications apply immediately

sysctladds persistence to /proc/sys settings

Statements added to /etc/sysctl.conf automatically reflected

under /proc after a reboot


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Package Management

Lesson 9

Th t t dd ft t R d H t Li


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There are two ways to add software to Red Hat Linux

- Through source code compilation

- Using RPMcommand

RPM command can be used to install/remove, query andverify installed software.

RPM files have a .rpm extension for naming convention

Primary RPM options includes

Install: rpm -i, --install

Upgrade: rpm -U, --upgrade

Freshen: rpm -F, --freshen

Erase: rpm -e, --erase

To install a rpm use


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rpm -i use -v for verbose installation

use -h to print hash mark to show installation progressrpm -ivh httpd-doc.i386.rpm

To remove a rpm userpme

To query a rpm userpmq rpmqi will show information about a particulatpackagerpm -qalists installed packagesrpmqa | grep will show whether a particularrpm is installed or not.

To upgrade a installed rpm


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rpmU

Kernel RPM are never upgraded usingU option To install a kernel rpm first install the rpm

To verify a installed package for integrity

rpm -V

rpmVp to verify a package beforeinstallation


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File system Management

Lesson 10

a file systemis a method for storing and organizingcomputer files and the data they contain to make it


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computer files and the data they contain to make iteasy to find and access them.

File systems use a data storage device such as ahard disk or CD-ROM.

More formally, a file system is a special-purposedatabase for the storage, organization, manipulation,

and retrieval of data. Linux provides many types of file systems like ext2,

ext3, reseirfs, Vfat etc.

Ext3 is the default filesystem for RedHat Linux.

Ext3 is journaling based filesystem.

Adding New Filesystems


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Identify Device

Partition Device

Make File system

Label File system

Create entry in /etc/fstab

Mount New Filesystem

Disk Partitioning


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Total maximum number of partitions supported by the kernel

are63 for IDE drives

15 for SCSI drives

Why should we partition drives

containment, performance, quotas, recovery Partitions can be created using fdiskcommand.

fdisk

fdiskl to display current partition table on all the devices

Run partprobecommand to reinitializes the kernel's in-memory version of the partition table

Use mkfs to make a new filesystem


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mkfs[ -V] [ -tfstype] [ fs-options]

mkfsVt ext3 /dev/hda1 mount the device to a mount point to make it usable

mountto

-t to specify filesystem type-o to specify mounting options

mount /dev/hda1 /mnt/

Add the filesystem to /etc/fstab to make the mount

persistent across reboot.

Use umount to unmount a mounted filesystem.

Use the remount option to change a mounted


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Use the remountoption to change a mountedfilesystem's options

mount -o remount,ro /data


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Network Configuration

Lesson 11

Drivers for network interface cards are built as modules

/etc/modprobe conf maps logical names to specific mod les


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/etc/modprobe.conf maps logical names to specific modules:

alias eth0 3c59x

interface names for Ethernet cards are eth0, eth1 and so on

Loopback adapter is named as lo

Display network interfaces by using

ifconfiga

Enable interface with ifup ethX

Disable interface with ifdown ethX

Device configuration is stored in text files

/etc/sysconfig/network-scripts/ifcfg-ethX

Global Settings are stored in /etc/sysconfig/network

NETWORKING es


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NETWORKING=yesHOSTNAME=server1.example.comGATEWAY=192.168.2.254

Domain Name Service translates hostnames tonetwork addresses

DNS Server address is specified by dhcp or in/etc/resolv.conf

search example.com cracker.orgnameserver 192.168.0.254

nameserver 192.168.1.254

Device Aliases


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We can Bind multiple IP addresses to a single NIC

eth1:1eth1:2

Make a separate configuration file for each virtual interfaceifcfg-ethX:x

Aliases must be configured to use static IPs, they can not be

configured using DHCP To verify network connectivity use

ping /etc/hosts is a local database of hostname to IP address

mappings /etc/nsswitch.conf sets precedence of DNS versus /etc/hosts


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Installation

Lesson 12

Anaconda is the Red Hat Enterprise Linux Installer Consists of two stages:

Fi t t t t th i t ll ti


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First stage starts the installationSecond stage performs the installation

The first stage consists of a installation kernel and aninitrd.img

Tasks of the First Stage:Initializes the InstallerParses command line arguments

Autodetects hardwareLoads additional driversSelects language, keyboard layout and installation methodSets up networking if required for installation

Task of second stage installer areLanguage and keyboard selectionInstallation Key


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Installation KeyDisk partitioningBootloader configurationNetwork and time zone configurationPackage selection

Installation can be done in graphical mode or text mode

Available Installation Methods areLocal CDROMHard driveNFS imageFTP

HTTP


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Partitioning layout must contain / and swap partition

Other partitions may be created like /var, /home etc.

Partitions can use software RAID and LVM

A default set of packages is automatically installed

Select Customize now to change the default set ofpackages

Packages can also be added after system is installed

L 13


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NFS and FTP

Lesson 13

File Transfer Protocol


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File Transfer Protocol(FTP) is a network protocol used to

transfer data from one computer to another through a networksuch as the Internet.

FTP is a file transfer protocol for exchanging and manipulatingfiles over a TCP computer network. An FTP client mayconnect to an FTP server to manipulate files on that server.

FTP sites are typically used for uploading and downloadingfiles to a central server computer, for the sake of filedistribution

In order to download and upload files to an FTP site, youneed to connect using a FTP client program.

vsftpd- the default Red Hat Enterprise Linux ftpserver


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Allows system, anonymous or user access

/etc/vsftpd/vsftpd.conf is the main configuration file

It is a SystemV-managed service

Package required for FTP is vsftpd

Daemon is/usr/sbin/vsftpd Script is /etc/init.d/vsftpd

FTP uses Port 21 (ftp) and 20 (ftp-data)

Configuration files are /etc/vsftpd/vsftpd.conf

/etc/vsftpd.ftpusers /etc/pam.d/vsftpd

NFS


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Network File System(NFS) is a network file systemprotocol originally developed by Sun Microsystems in1984.

It allows a user on a client computer to access filesover a network

The server implements NFS daemon processes inorder to make its data generically available to clients

The client machine can requests access to exported

data, typically by issuing a mount command.

Exports are listed in /etc/exports

Each entry specifies the hosts to which the filesystem is


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y p yexported plus associated permissions and options

Server notified of changes to exports list with exportfs -rorservice nfs reload

The NFS server is an RPC service and thus requiresportmap

It is a System V-managed service

Package required is nfs-utils

Daemons are rpc.nfsd, rpc.lockd, rpciod, rpc.mountd,rpc.rquotad, rpc.statd

Use showmount -e hostnameto show available exports on a

server.

/etc/exports syntax is/some/directory Host(options)


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/some/directory Host(options) When specifying hostnames, use the following methods

single hostWhere one particular host is specified with afully qualified domain name, hostname, or IP addresswildcardsWhere a * or ? character is used to take intoaccount a grouping of fully qualified domain names that matcha particular string of letters.

*.csc.comIP networksAllows the matching of hosts based on their IPaddresses within a larger network. For example,192.168.1.0/24

Default options arero, sync, root_squash

Lesson 14


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Troubleshooting

Lesson 14

Filesystem Recovery


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Filesystem recovery may be needed after crash or

improper shutdown

journal indicates if recovery is needed

only need to check files recorded in journal

/etc/rc.d/rc.sysinitruns fsckon filesystems markedin /etc/fstab

fsck is a front end to other programs

A failed fsck must be run manually

Rescue Environment


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Required when root filesystem is unavailable

Boot from CDROM (boot.iso or CD #1)

Type Linux rescue at the installation prompt

Anaconda will ask if filesystems should be mounted

Currently installed environment will be mountedunder /mnt/sysimage

Run chroot /mnt/sysimage to access currentlyinstalled environment.

Type exit when done to reboot the system.

END


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Thank you for your attention!!

Any Questions?

Trainer Contacts


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Seat No: SA 77Ext. no. 709363

Mobile no. 9310470605

Training material will be uploaded on TPD

(Training Process Database IN-NDA02)

Documents

Redhat Linux Basics