Filesystem Hierarchy System

FILESYSTEM HIERARCHY SYSTEM

Linux uses single rooted, inverted tree like filesystem hierarchy

/ this is top level directory

it is parent directory for all other directories

it is called as ROOT directory

it is represented by foward slash(/)

c:\ of windows

/root it is home directory for root user(super user)

it provides working enviorment for root user

c:\Documents and Settings\Administrator

/home it is home directory for other users

it provied working environment for other users(other than root)

c:\Documents and Settings\username

/boot it contains bootable files for linux

like vmlinuz(kernel) ..... ntoskrnl

initrd(INITial Ram Disk)and

GRUB(GRand Unified Bootloader).... boot.ini, ntldr

/etc It contains all configuration files

like /etc/passwd..... user info

/etc/resolv.conf... Preffered DNS

/etc/dhcpd.conf.... DHCP server

c:\windows\system32\dirvers\

/usr By default softwares are installed in /usr directory

(Unix Sharable Resources)

c:\program files

/opt It is optional directory for /usr

It contains third party softwares

c:\program files

/bin It contains commands used by all users

(Binary files)

/sbin It contains commands used by only Super User(root)

(super user's binary files)

/dev It contains device files

like /dev/hda ... for harddisk

/dev/cdrom ... for cdrom

similar to device manager of windows

/proc It contain process files

Its contents are not permanent, they keep changing

It is also called as Virtual Directory

It's file contain usefull information used by OS

like /proc/meminfo ... information of RAM/SWAP

/proc/cpuinfo ... information of CPU

/var It is containing variable data like mails, log files

/mnt It is default mount point for any partition

It is empty bydefault

/media It contains all of removable media like cdrom, pendrive

/lib It contains library files which are used by OS

it is similar to dll files of windows

library files in linux are SO(shared object) files

/tmp It stored temporary files

.................................................................................

Basic commands:-

pwd.... print present working dir

[root@sys10~]# pwd

/root

[root@sys10boot]# pwd

/boot

date...... to display date and time

# date (press enter)

who ........ to see who is logged in

# who( press enter )

whoami ..... to show who is working on present terminal

# whoami (press enter)

cal... to show calender

# cal

to show present month's calender

# cal 2008

to show calender of year 2008

mkdir..... make directory

syntax # mkdir

ex # mkdir one

# mkdir one/two

# mkdir one/two/three

we can use -p option to create dir inside a dir

ex # mkdir -p one/two/three

rmdir .... to delete an empty dir

syntax # rmdir < dir name>

ex # rmdir one

error...... Directory not empty

# rmdir one/two/three

# rmdir one/two

# rmdir one

how to create files:-

we can use 'touch' or 'cat' command

touch command is used to create blank files

size of file created by touch is zero bytes

syntax # touch

ex # touch first.txt

ex # touch second.txt thrid.doc fourth.bat

cat command is used to create file and diplay the contents of file also

syntax # cat > < new file name >

ex. # cat > first.txt

type the contents of file here

ksldjf;lkas

asdkljfja;sdf

asdfashflkjasdfh

................

press ctrl + d to save the file

how to see contents of file

ex # cat first.txt

type the contents of file here

ksldjf;lkas

asdkljfja;sdf

asdfashflkjasdfh

................

how to copy file:

cp command is used to copy a file

syntax # cp < source name > < target name >

ex # cp /root/first.txt /root/one/two/three

this command will copy first.txt file to three directory with same name

ex # cp /root/first.txt /root/one/two/three/new.txt

this command will copy first.txt file to three directory with new.txt name

by default cp command will not copy directory

we have to use -r switch to copy directory also

ex # cp -r /root/one/* /var

this command will copy all the contents of one directory to var directory

note:- we can use wildcard characters

* means multiple characters

? means single character

how to delete a file:

rm command is used to delete a file/directory

syntax # rm < file/dir name >

ex # rm /root/first.txt

it will ask for confirmation, press y to delete file

ex # rm -f /root/first.txt

it will not ask for confirmation

to remove a directory also we have to use -r option

ex # rm -rf /root/one

this command will delete one directory with all its contents,

without confimation.

mv ..... to move file/dir

this command is also used to rename file/dir

syntax # mv < source name > < target name >

ex # mv /root/first.txt /root/one/two/three

this comamnd will cut first.txt file and paste it in three directory

ex # mv /root/first.txt /root/new.txt

this command will rename first.txt file to new.txt

cd..... change directory

syntax # cd < dir name >

[root@sys10~]# cd /var/log

[root@sys10 log]# pwd

/var/log

[root@sys10 log]# cd /root

[root@sys10~]# pwd

/root

cd - means switch directory to previous directory

cd ~ means go back to home directory of user

cd .. means go to parent directory

cd ../.. means go to 2 level parent directory

cd means go back to home directory of user

ls......... list directories

this command is used to list the contents of a directory

generally following options are used with 'ls'

ls -l long listing

ls -a list all files and directories

ls -R Recursive order

ls -r reverse order

ls -i to list inode numbers

ll same as 'ls -l'

the output of ll command shows following iformation:-

file type

permissions

links

owner of file

owner's group name

size of file in bytes

date and time of modification

file name

..............................................................................

VI visual display editor

VIM visual display editor improved

this is command mode editor for files

other editors are emacs, gedit

vi editor is most popular

it is having 3 modes:

1 command mode

2 insert mode (edit mode)

3 extended command mode

Insert mode:

i Insert at current cursor position

I Insert at start of line

a Append at current cursor position

A Append at the end of line

o Insert line below cursor position

O Insert line Above cursor position

Ins-key same as i

ex command mode:

:w to save the file

:wq to save and quit

:q to quit without saving

:q! to quit without saving (forcefully)

:wq! to save and quit file (forcefully)

{used for read only files}

:se nu to SEt line NUmber

:se nonu to remove line number

:14 to move cursor to line no. 14

command mode:

dd to delete a line (cut)

4dd to delete 4 lines (cut)

yy to copy a line (yank)

10yy to copy 10 lines (yank)

p to paste lines below cursor position

P to past lines above cursor position

u to undo

ctrl+r to redo

/ to find a text inside a file

How to find and replace:-

:s///

range can be:

% complete file

10,$ from 10th line to last line

15,20 from 15th line to 20th line

option can be:

g to replace all the occurence in same line

i to ignore case sensitivity

ex. :1,$s/cat/dog/gi

to find cat,CAT,Cat,cAT and replace with dog in complete file

more and less commands are used to see the contents of a file page wise.

syntax. # more < file name >

ex. # more file1.txt

now to see contents page wise press space

to see contents line wise press enter

less command is same as more

but to quit less command we have to press q

head ........ this command is used to see first 10 lines of a file.

ex. # head file1.txt

to see the first 'n' lines:

ex. # head -n file1.txt

tail ....... this command is used to see last 10 lines of a file.

ex. # tail file1.txt

to see the last 'n' lines:

# tail -n file1.txt

redirection:- used to give output of one command to a file.ex. # cat file1.txt >> file2.txt

this command will APPEND the contents of file1.txt to file2.txt

# ls -l >> file3.txt

the output of 'ls-l' is saved inside file3.txt file.

pipe:- used to give output of one command to another command

ex. # cat file1.txt | more

``:``

this is pipe symbol

Note: grep:- Global Regular Expression Print

awk:- The name AWK is derived from the family names of its

authors

alfred Aho, peter Weinberger, and brian Kernighan

# ll | grep "^-"

to show only files

# ll | grep "^d"

to show only directory

# ll | grep "^-" | wc -l

to count no. of files

wc..... word count

# wc file1.txt

it will show no. of lines

no. of words

no. of characters

# wc -l file1.txt

shows only no. of lines

# wc -w file1.txt

shows only no. words

# wc -c file.txt

shows only no. of characters.

..............................................................27/03

User Group Administration

whenever a user is created in linux :-

its home directory is created(/home/username)

its mail box is created(/var/spool/mail)

unique UID & GID are given to user

UID for system users 0 to 499

UID for normal users 500 to 60,000

Redhat Enterprise Linux and fedora used UPG scheme

UPG... User Private Group

it means that whenever a user is created is has its own private group

how to create user:

syntax. # useradd

options are

-u user id

-G Secondary group id

-g primary group id

-d home directory

-c comment

-s shell

ex. # useradd user1

user1 is created

ex. # useradd -u 1001 -d /anydirectory -s /bin/sh user2

user2 is created with uid=1001,home=/anydirectory,shell=/bin/sh

all of user information is stored in /etc/passwd file.

it contains 7 fields:-

user1:x:500:500::/home/user1:/bin/bash

1 2 3 4 5 6 7

1 user login name

2 mask password

3 uid

4 gid

5 comments( bydefault no comment)

6 user's home directory

7 user's login shell

after creating users we can modify its properties by using:

syntax. # usermod

options are:

all of the options which are used with useradd command and,

-l to change login name

-L to LOCK account

-U to UNLOCK account

ex. # usermod -l newname oldname

ex. # usermod -L newname

ex. # usermod -U newname

note:- when a account is locked it will show !(exclamation mark) in

/etc/shadow file.

how to set password:

syntax. # passwd

ex. # passwd user1

ex. # passwd root

the password information is stored inside /etc/shadow file

it contains encrypted password

linux uses MD5 and DES algorithms for encrypting passwords

MD5 Message Digest version 5

DES Data Encryption Standard

how to delete a user account:

syntax. # userdel

ex. # userdel user1

it will delete user1 but home directory will not be deleted

ex. # userdel -r user2

it will delete user2 and home directory will also be deleted

...........................................................................

to create a group:

syntax. # groupadd

options:

-g to set GID

ex. # groupadd -g 1010 sales

ex. # groupadd mktg

to add/delete secondary users to group

syntax # gpasswd

ex. # gpasswd -a user1 sales

to add a single user

ex. # gpasswd -M user2,user3,user4 sales

to add multiple users

ex. # gpasswd -d user1 sales

to delete secondary user from member list

to delete group ( group must not contain any primary user )

syntax. # groupdel

ex. # groupdel sales

note: all information of group is stored in /etc/group file

it contain list of secondary members also.

..............................................................................

PERMISSIONS:-

to see the present permission on any file:-

# ls -ld

permission are applied on three levels:-

owner or user level

group level

others level

access modes are of three types:-

r read only

w write/edit/delete/append

x execute/run a command

access modes are different on file and directory

file dir

r open the file 'ls' the contents of dir

w write,edit,append,delete file add/del/rename contents of dir

x to run a command/shell script to enter into dir using 'cd'

the output of ls -ld command shows following properties

-rw-r--r-- 2 root root 54 15 march ..... file1.txt

`````````` `` ```` ```` `` `````````````` ```````

filetype+permission, links , owner, grp name of owner, size in bytes,

date of modification, file name.

file types:-

- normal file

d directory

l link file(shortcut)

b block file(harddisk,floppydisk)

c character file(keyboard,mouse)

permission can be set on any file/dir by two methods:-

1 absolute method(numbers)

2 symbolic method(ugo)

to set the permission on file/dir 'chmod' command is used

bydefault permissions on file and dir:-

file dir

root 644 755

normal user 664 775

here,

read=4

write=2

execute=1

different permissions on file and directory:-

file dir

read file can be open,read contents of dir can be listed (ls)

write contents of file canbe changed contents of dir can be deleted,created

execute command/script can be run user can enter into dir (cd)

how to set permission on file/dir:-

syntax. # chmod

ex. # chmod 777 /file1.txt

or

# chmod u=rwx,g=rwx,o=rwx /file1.txt

or

# chmod ugo=rwx /file1.txt

this command is used to give full permission to all.

ex. # chmod 000 /file.txt

or

# chmod u=-,g=-,o=- /file.txt

or

# chmod ugo=- /file.txt

this command is used to remove all permission.

note:- UMASK- is the number which is removed from default permission of file/

dir.

default umask of root user is 022

default umask of unprivledged user is 002

for root user:-

file dir

default perm. 666 777

subtract UMASK -022 -022

Resulting perm. 644 755

for normal user:-

file dir

def. perm. 666 777

subtract UMASK -002 -002

Resulting perm. 664 775

...............................................................................

04/04/08

Advanced Permissions:

There are 3 types of adv. permissions:

SUID ... userlevel

SGID ... Grouplevel

Sticky bit others level

to set adv permissions by using numeric method we use

suid = 4

sgid = 2

stickybit= 1

SUID:-

If suid is set on any command then any normal user can run

that command with privledges of root user

like, Defaultly ping command is having suid, so all users can

run that command but if suid is removed then 'permission denied'

ex.

# whereis ping

/bin/ping

# ls -ld /bin/ping

-rwsr-xr-x ..........

````` this means SUID is set bydefault

how to remove SUID:

# chmod 0755 /bin/ping

# ls -ld /bin/ping

-rwxr-xr-x ................

```` this means SUID is removed

how to check:

log in as normal user and try to ping

it will display error..... opration not permitted

SGID:-

SGID is used for group inheritance, files and directories will

get groupname from their parent directory

ex.

# mkdir /mywork

# chmod 777 /mywork

# chgrp sales /mywork

# chmod 2777 /mywork

# ls -ld /mywork

now login as sales group members, create some files, and check their

properties

Sticky Bit:-

If sticky bit is set, then only owner can delete that file/dir

ex.

# mkdir /mywork

# chmod 1777 /mywork

# ls -ld /mywork

it will display rwt.... for sticky bit

# su user1

$ touch /mywork/file1

$ exit

# su user2

$ rm /mywork/file1

error.... permission denied

..............................................................................

Network-Client configuration:

ifconfig:-

Interface configuration(Network Interface Card)

it is used to set ip addr temporarily

it is also used to check ip addr

how to set ip addr temporarily:-

# ifconfig eth0 192.168.1.X

how to check ip add:-

# ifconfig eth0

it will display ip addr, hardware addr, subnet mask .....

netconfig:- network configuration is used to set ip addr,

subnet mask, preffered dns, default gateway

how to set ip addr:

# netconfig ( press enter )

ok

192.168.1.X

255.255.255.0

enter

enter

ok

# service network restart

restart network service to update new ip addr

note:- if netconfig is not working then pakage is not installed

you can install this pakage by using rpm

system-config-network

or

neat( Network Administration Tool )

used to set ip addr in Graphical mode

ifup:- interface up

this command will enable lan card

# ifup eth0

ifdown:- interface down

this command will disable lan card

# ifdown eth0

ethtool:- used to check whether lan card is detected or not:

# ethtool eth0

yes

How to change Hostname:

hostname:- this command is used to set hostname temporarily

and view hostname

to see hostname:-

# hostname (press enter)

to set hostname temporarily:-

# hostname sysX

to make hostname permanent:-

# vi /etc/hosts

192.168.1.X sysX

# vi /etc/sysconfig/network

HOSTNAME=sysX

to check log off and log in again and use 'hostname' command

Partitions:-

fdisk command is used in linux to create,delete,view,manage partitions

# fdisk -l

Disk /dev/hda: 41.1 GB, 41174138880 bytes

Device Boot Start cyl End cyl Blocks Id File System

/dev/hda1 * 1 1020 8193118+ 7 HPFS/NTFS

/dev/hda2 1021 1033 104422+ 83 Linux

Note:- 1Block=1KB

Id is used by system to identify the type of partition.

* means it is a boot partiton.

How to create new partition:-

# fdsik < device name >

# fdisk /dev/hda

command(m for help):

commands are:-

n new partition

d delete partition

p print partition table

t set system id(tag)

w to save and quit

q to quit without saving

m prints this help

l to list system id

to create new partition:-

command(m for help): n

first cyl..........: (press enter)

size in mb +sizeM..: +100M

command(m for help): w

it will display warning:- kernel use old partition table.

# partprobe /dev/hda

now check partition:-

# fdisk -l

How to delete partition:-

first note the partition no. by using 'fdisk -l' command.

for example----/dev/hda9

then,

# fdisk /dev/hda

command(m for help) : d

partition no.(1-9) : 9

command(m for help) : w

# partprobe /dev/hda

Note:- dont delete partition already created.

delete only that partition which u hav created.

How to format partition:-

mkfs command is used to make file system.

to format partition using ext3 file system:-

# mkfs.ext3 /dev/hda9

to format partition using ext2 file system:-

# mkfs.ext2 /dev/hda9

to format partition using vfat file system:-

# mkfs.vfat /dev/hda9

How to mount the formated partition:-

mount command is used to create a link between physical partition

and an empty directory.

you can use /mnt directory for mounting any partition

or you can create your own dir. also

# mount < mount point>

# mount /dev/hda9 /mnt

# mount /dev/hda10 /cms

after mounting you can create file/dir in that partition:-

# cd /mnt

# touch 1 2 3 4

# mkdir one two three four

mount command is also used to check whether the partition is mounted

or not

# mount (press enter)

it will show all currrently mounted partitions

Label:- label of partition is name of partition

(ex. in windows .....disk1_vol1, localdisik)

(ex. in linux ..... /boot, /root)

How to check current label:

# e2label < partition no. >

# e2label /dev/hda1

# e2label /dev/hda2

how to change label:

# e2label /dev/hda9 Myname

# e2label /dev/hda10 yourname

How to convert ext2 to ext3

# tune2fs -j /dev/hda9

How to convert ext3 to ext2

# tune2fs -O ^has_journal /dev/hda9

(capital O)

................................................................................

05/04/08

SWAP

swap is a file system, it is similar to virtual memory of windows

swap space is used to improve the system performance

How swap works?

system identifies the idle process in RAM(memory) and sends it to

swap space, so that RAM again becomes free.

swap space is created on Hard disk

Rule to create Swap?

if size of RAM < 2GB

then size of SWAP=2*RAM

else

size of SWAP= 2 + RAM

How to view info about swap

# free

# more /proc/meminfo

# more /proc/swaps

# swapon -s

-s option is to show swap

How to increase Swap size

1. first create a new partition using fdisk command

ex. /dev/hda9

2. make it a swap partition:-

# mkswap /dev/hda9

3. enable swap on this partition:-

# swapon /dev/hda9

check it by using 'swapon -s'

How to Break root password:-

1. restart system

# init 6

2. go to single user mode

at the grub boot screen select Redhat and press 'a'

then give space and type '1'

then press enter

3. at the shell prompt change the root password

sh# passwd root

******

******

4. restart the system

# init 6

What is GRUB?

GRand Unified Bootloader is the default boot loader program for RHEL5

configuration file for GRUB is

/boot/grub/grub.conf

its contents are:-

default=0 ........default os is Redhat

timeout=5 ........time to change os

splashimage=(hd0,1)/grub/splash.xpm.gz ........grahical screen

hiddenmenu ........hides os options

title Red Hat Enterprise Linux Server (2.6.18-8.el5) ...... name of 1st os

root (hd0,1) ..... partition

kernel /vmlinuz-2.6.18-8.el5 ro root=LABEL=/1 rhgb quiet ...kernel

initrd /initrd-2.6.18-8.el5.img ..... Initial RamDisk

title Other ....... name of 2nd os

rootnoverify (hd0,0) | boot info

chainloader +1 | of 2nd os(windows)

How to set GRUB password:-

1. # grub-md5-crypt >> /boot/grub/grub.conf

now type password for two times

2. # vi /boot/grub/grub.conf

remove last 2 lines:-

password

retype password

cut last line where encrypted password is written.

paste it below ' hiddenmenu '

ex.:-

hiddenmenu

passowrd --md5 $123abc.xyz456$pqr.

title Red Hat Enter.....

3. save and exit file, restart system and verify.

How to remove GRUB password:-

1. boot from RHEL 1st cd

2. at the boot prompt type 'linux rescue' and press enter

boot: linux rescue

3. keyboard ...... ok

4. language ..... ok

5. network support .... no

6. rescue ......... continue

7. shell will appear type following command:-

sh# chroot /mnt/sysimage

8. open grub configuration file and remove password line:-

sh# vi /boot/grub/grub.conf

delete line below 'hiddenmenu'

save and exit

9. remove cd and restart

..............................................................................

08/04/08

Symbolic Link

There are two types of Links:-

Hard link Soft Link

1 size of both file is same size of link file is equal to no.

of characters in the name of original file

2 can't be created accross can be created accross

partition partiton

3 inode no. of both file is inode no. of source and link file

same is different

4 if original file is deleted if original file is deleted

then also link will contain link is broken and data is

data lost

5 BACKUP FILE SHORTCUT FILE

command used to create Hard link:-

syn # ln

to check use:-

# ls -ali

command used to create Soft link:-

syn # ln -s

to check use:-

# ls -ali

..........................................................................

31/03/08

............................................................................

swap file system

swap file system is used to improve system performance

it is the part of your hard disk which is used for storing idle process

of RAM.

it is similar to virtual memory of windows os

how to create new swap partition.

1 create new partition using fdisk command

2 make swap partition using mkswap

3 enable swap partition using swapon

4 check by using free, /proc/meminfo , swapon -s

2 #mkswap /dev/hda11

3 #swapon /dev/hda11

4 #free

it will show total swap space.

note:- in first step, while creating partition we have to set system ID

by using 't' option

set tag no. 82 to make it swap/solaris partition.

if we not set tag(system ID) then swap partition will not work.

Quota:-

quota are used to restrict the amount of disk usage by any user,

group on a particular partition.

QUOTA

user level . group level

blocks inodes .blocks inodes

(size in kb) (no. of files) .(size in kb) (no. of files)

inode:- Index node no. it is used by system to identify the

properties of file like, file type, permission, owner,

group, size in blocks, no. of links, time stamps.

Inode no. is unique to a file.

how to see inode no.......... # ls -il < file name>

steps to implement quota:-

1 create a new partition.(fdisk)

2 format it(mkfs.ext3)

3 mount partition using userquota,groupquota option(mount)

4 check mounted partition(mount)

5 create user,group

6 create quota file inside quota partition(quotacheck)

7 enable quota on quota partition(quotaon)

8 specify quota limits(edquota)

3 # mount -o usrquota,grpquota /dev/hdaX /mnt

4 # mount

5 # useradd user1; #useradd user2

# passwd user1

# passwd user2

6 # quotacheck -cugv /dev/hdaX

options:-

-c to create quota database files

-u user quota

-g group quota

-v verbose

to check whether files are created or not:-

# ls /mnt

7 # quotaon /mnt

8 to set userlevel quota:-

# edquota -u user1

to set group level quota:-

# edquota -g grpname

after 8th step quota file will open

here,

soft means --- limit after which warning message is displayed

hard means --- limit after which error message is diplayed

to check quota limits, log on as user and create file/dir

or use "repquota " command

..........................................................................................

03/04/08

RAID

Redundant Array of Inexpensive/Independent Disk

2 or more hard disk are combined to create RAID, it is used in servers

with SCSI Harddisk.

Redhat supports following RAID Levels:-

RAID 0 (stirping) 2min 32max

RAID 1 (mirroring) 2min 2max

RAID 4 (striping with Parity disk) 3min 32max

RAID 5 (striping with distributed parity) 3min 32max

how to implement RAID 5 on redhat:-

'mdadm' command is used for administration of MetaDisk in linux.

syntax. # mdadm -C -nX ..... -lX

-C to create metadevice

-n to set no. of harddisk

-l to set RAID level

ex. # mdadm -C /dev/md0 -n3 /dev/hda9 /dev/hda10 /dev/hda11 -l5

/dev/md0 is metadisk

/dev/hda9,10,11 are new partitions

-n3 means no. of harddisk=3

-l5 means RAID level=5

after creating RAID to check it:-

ex. # mdadm -D /dev/md0

-D to display information

to use RAID Partition format it:-

ex. # mkfs.ext3 /dev/md0

make a mount point:-

ex. # mkdir /cms

now mount RAID Partition on /cms

ex. # mount /dev/md0 /cms

now create some files and directory in /cms.

how to make any RAID Device faulty

ex. # mdadm -f /dev/md0 /dev/hda10

/dev/hda10 from /dev/md0 is now fautly

how to check it:-


it will show fautly device----- /dev/hda10

how to remove any Faulty Device from RAID

ex. # mdadm -r /dev/md0 /dev/hda10

how to check it:-


it will show only 2 devices..... one device is removed.

how to add newly created partition to already existing RAID:-

ex. # mdadm -a /dev/md0 /dev/hda12

here /dev/hda12 is newly created partition.

how to check:-


it will show spare building for some time.

then it will show active synchronous.

.............................................................................

04/04/08

Rule for attending Linux class:-

never come late, after 7:45am nobody means nobody will be allowed.

``````````````````````````````````````````````````````````````````

LVM....... Logical Volume Manager.

In linux, lvm is used to create logical partitions, called as

logical volumes.

we can easily resize logical volumes, without data loss.

LVM can be created using one or more harddisk.

We will implement LVM on 3 different partitions of single harddisk.

Diagram:-

How to create Physical Volume:-

# pvcreate /dev/hda9 /dev/hda10 /dev/hda11

How to check Physical Volume:-

# pvdisplay | more

How to create Volume Group (name of volume group is CMS):-

syntax # vgcreate .........

# vgcreate cms /dev/hda9 /dev/hda10 /dev/hda11

How to check Volume Gorup:-

syntax # vgdisplay

# vgdisplay cms

How to create Logical Volume (name of Logical Volume is LINUX):-

syntax # lvcreate -L +sizeM -n

# lvcreate -L +100m cms -n linux

another logical volume(name is CCNA):-

# lvcreate -L +50m cms -n ccna

another logical volume(name is MCSA):-

# lvcreate -L +60m cms -n msca

How to check Logical Volume:-

syntax # lvdisplay

# lvdisplay linux

# lvdisplay ccna

# lvdisplay mcsa

How to write data into Logical Volume:-

first format Logical Volume:-

# mkfs.ext3 /dev/cms/linux

then mount Logical Volume on a Directory:-

# mount /dev/cms/linux /mnt

now create some files/dir in mount point:-

# cd /mnt

# touch 1 2 3 4 5

How to resize LV:-

syntax # lvresize -L +/-sizeM

# lvresize -L +10M /dev/cms/linux

# lvresize -L -20M /dev/cms/linux

How to remove LV:-

# lvremove /dev/cms/mcsa

How to add new Physical Volume to already existing Volume Group:-

first create new partition.......... /dev/hda12 using fdisk

now create physical volume:-

# pvcreate /dev/hda12

now add this physical volume to Volume Group:-

# vgextend cms /dev/hda12

RPM

RedHat Pakage Manager

sample rpm file:-

vsftpd-2.0.5-10.el5.i386.rpm

pakagename-version-release.enterpriselinux5.architecture.extension

There are two way to install rpm:-

1 standalone installation(rpm file is on your sys/cdrom)

2 network installation(rpm file is on Server)

How to install rpm Loacally(standalone installation):-

first mount cd/dvd on /mnt directory:-

# mount /dev/dvdwriter /mnt

# cd /mnt

# cd Server

# ls vsftpd*

vsftpd-2.0.5-10.el5.i386.rpm

now install this pakage:-

# rpm ivh vsftpd-2.0.5-10.el5.i386.rpm

preparing..... ############################[100%]

#####################################[100%]

options:-

i install pakage

U(capital U) Upgrade Pakage

v verbose mode installation

h hash

--force to forcefully install pakage, overwrite previous

installation.

--nodeps to remove pakage but dependency will not be removed.

-e to erase/remove installed pakages

-q to query installed pakages

-qa to query all installed pakages

-qd to see documentations files inside pakage

-ql to see all files inside pakage

-qs to see the status of files inside pakage

-qi to see detailed information of installed pakage

-qip to see detailed info of not installed pakage

How to install pakages from network server:-

Note:- ip addr of server in lab is 192.168.10.10

share directory name is /var/ftp/pub/Server

here all rpm are already copied.

on client machine:-

method 1:- NFS

first ping server

# ping 192.168.10.10

then mount the shared directory from server to any local directory:-

# mount 192.168.10.10:/var/ftp/pub/Server /mnt

```````````` ``````````````````` ````

IP add of server:/location of shared dir local dir.

go to mount point

# cd /mnt

now install pakage:-

# rpm -ivh

# rpm -ivh vsftpd-2.0.5-10.el5.i386.rpm

(try dialog rpm also)

method 2:- FTP

first ping server

# ping 192.168.10.10

then install pakages using ftp method:-

# rpm -ivh ftp://192.168.10.10/pub/Server/

# rpm -ivh ftp://192.168.10.10/pub/Server/vsftpd-2.0.5-10.el5.i386.rpm

YUM

YellowDog Updater Modified

yum feature was avialable with fedora, now it is available in RHEL5

RPM feature is used to install pakages but its main drawback is

Failed Dependency Resolution.

yum automatically identifies dependency in pakages,& install those

dependencies also.

by using YUM we can install, remove, list pakages and group of pakages.

Repository:- it is the place where we create RPM Dump

on server we copy all rpm from RHEL cd/dvd

here a list of all those pakages is created

this list of pakages is called Repository.

generally we copy all rpm of 'Server' directory of rhel cd/dvd to

/var/ftp/pub/Server directory on Server.

Server side configuration:-

1. copy rpms from cd/dvd to /var/ftp/pub/Server

2. install pakage createrepo* from cd

3. create repository

4. edit configuration file /etc/yum.repos.d/rhel-debuginfo.repo

Client side configuration:-

1. check ip addr

2. ping server(192.168.1.10)

3. edit configuration file /etc/yum.repos.d/rhel-debuginfo.repo

4. start installing pakages using 'yum' command.

steps for Server:-

if vsftpd pakage is not installed then install it

make dir... /var/ftp/pub/Server

1 # mount /dev/dvdwriter /mnt

# cp -r /mnt/Server/* /var/ftp/pub/Server

`````````````` ```````````````````

source target

# cd /mnt

2. # rpm -ivh createrepo*

3. # createrepo -g /mnt/Server/repodata/comps* /var/ftp/pub/Server/

source target

4. # vi /etc/yum.repos.d/rhel-debuginfo.repo

edit following lines:-

#baseurl (remove hash)

#enabled (remove hash)

baseurl=ftp:///pub/Server

(192.168.1.10)

enabled=1

steps for Client side configuration:-

just edit same file /etc/yum.repos.d/rhel-debuginfo.repo

and start installing pakages using 'yum' command

yum command :-

# yum install rpm -ivh

# yum remove rpm -e

# yum list installed rpm -qa

# yum list installed rpm -q

# yum grouplist -----

# yum upgrade rpm -Uvh < pkg name>

# yum groupinstall -----

..............................................................................

08/04/08

BACKUP & RESTORE

TAR:- tape archive

this command is used to create archive.

syntax: # tar

options are:-

-c to create a new archive

-v verbose mode

-f to create archive of files also

-x to extract archive

-z to zip archive using gzip

-j to zip archive using bzip2

# tar -cvf /var/home.tar /home

to create archive of /home directory inside /var directory

# tar -tvf /var/home.tar

to see the contents of home.tar archive without extracting

# tar -xvf /var/home.tar

to extract /var/home.tar inside /var

# tar -xvf /var/home.tar -C /home

to extract /var/home.tar to /home directory

# tar -cvfz /var/home.tar /home

to create a tar of /home and zip it using gzip utility

# tar -xvfz /var/home.tar

to extract home.tar using gunzip utility

# tar -cvfj /var/home.tar /home

to create tar and zip it using bzip2 utility

# tar -xvfj /var/home.tar

to extract home.tar uing bunzip2 utility

after creating tar how to zip

there are two zip commands used, gzip/gunzip and bzip2/bunzip2

bzip2 is more powerfully than gzip

to zip using gzip:-

# gzip

# gzip /var/home.tar

# ls -ld /var/home.tar.gz

to unzip using gunzip:-

# gunzip /var/home.tar.gz

to zip using bzip2:-

# bzip2 /var/home.tar

# ls -ld /var/home.tar.bz2

to unzip using bunzip2:-

# bunzip2 /var/home.tar.bz2

Remote copy:-

scp---- secure copy

this command is used to copy contents of remote system,

we can take remote backup using this command

syntax # scp -r

# scp -r 192.168.1.1:/home 192.168.1.2:/tmp

source pc target pc

this command will ask for root password of remote pc

Note:- this command is based on ssh

ssh is Secure SHell

ssh is secure version on telnet

it uses port no. 23 like telnet

but the data, password sent using ssh is secure because

it encrypts data before sending

using ssh we can SHARE REMOTE DESKTOP in text mode.

HOW?

# ssh

password of root:

to run a command on remote pc:-

# ssh

# ssh 192.168.1.1 init 0

this command will shutdown 192.168.1.1 pc

How to configure hostname:-

Hostname is pc name

it is used to identify the system on network

bydefault hostname is localhost.localdomain

to change hostname temprorily:-

# hostname

to see hostname :-

# hostname (press enter)

to change hostname permanently:-

open and edit configuration file:-


HOSTNAME=sysX

#vi /etc/hosts

192.168.1.X sysX

logout and again login

NFS --- Network File System

NFS server is used to share a dir between linux-linux or linux-unix machine

NFS SERVER:- system which share(export) its directory for network

NFS CLIENT:- system which mounts server's directory

NFS SERVER configuration :-

pakages:- nfs-utils*

portmap*

port no. 2049.... nfs

111.....portmap

configuration file /etc/exports

Services nfs

portmap

Daemon statd,mountd,lockd,nfsd

Steps:-

server side:-

create share folder:-

# mkdir /share

give full permission:-

# chmod 777 /share

export(share) this directory:-

# vi /etc/exports

/share 192.168.1.0/255.255.255.0(rw,sync)

NOTE:- /share *(ro,async)

restart service:-

# service portmap restart

# service nfs restart

client side:-

mount server's dir on /mnt

# mount 192.168.1.10:/share /mnt

check the contents:-

# cd /mnt

# ls

Note:- # showmount -e

this command is used to see what is shared on 'ip add'

FTP SERVER

FILE TRANSFER PROTOCOL- used to upload and download files from ftpserver

following are different ftp server:-

wuftp washington university ftp

proftp

vsftp very secure ftp

FTP SERVER:- system which is having shared file/dir

FTP CLIENT:- system which is uploading/downloading file to server

Pakages:- vsftpd*.rpm

Port no. 20 for data transfer

21 for connection control

configuration file /etc/vsftpd/vsftpd.conf

/etc/vsftpd/user_list

/etc/vsftpd/ftpusers

services vsftpd

Daemon vsftpd

Steps:-

1 check for installed pakages

# rpm -q vsftpd

if not installed then install it using nfs method

# mount 192.168.1.10:/var/ftp/pub /mnt

# cd /mnt

# cd /Server

# rpm -ivh vsftpd*

2 create shared dir inside /var/ftp

# cd /var/ftp

# mkdir upload

# mkdir download

give write permission on upload directory

# chmod ugo+w upload

create some files in download directory

# cd download

# touch one two three

3 open main configuration file:-

# vi /etc/vsftpd/vsftpd.conf

you can change any of the following options:-

line no.

12 anonymous_enable=YES

to allow anonymous user to log into ftp server

user name for anonymous users are,

ftp

anonymous

15 local_enable=YES

to allow local users that are created on server machine to log into ftp server from

client side

example of local users is user1,user2,raj,ravi

27 anon_upload_enable=YES

to allow users to upload file to ftp server

bydefault any user is not permitted to upload files to server, he can only download

115 userlist_enable=YES

4 restart ftp service

# service vsftpd restart

or to reload service without shutting down use:-

# service vsftpd reload

Client Side configuraion:-

1 connect to ftp server:-

# ftp 192.168.1.10

(ip addr of server)

it will ask for username, password

default user is ftp/anonymous

default password is ftp/anonymous

or you can also use any username that is created on server(local user)

2 download files

go to download directory

ftp> cd download

ftp> get one

3 upload file

go to upload directory

ftp> cd upload

ftp> put localfilename

4 disconnect ftp server

ftp> bye

Note:-

if local_enable=YES is given in vsftpd.conf file

it means local users of server can also login from client side

ex. of local users are user1,user2, and even root

but bydefault root user is NOT allowed to login from network

so to deny any local user to login into ftp server, enter its name in

ftpusers file or user_list file, and reload the service

How to access FTP Server in graphical mode:-

open web browser( mozila filefox )

type addr

ftp://

like

ftp://192.168.1.10(press enter)

............................................................................

10/04/08

SAMBA SERVER

Windows OS share file/folders using SMB(server message block) protocol

Windows OS share file/folder over tcp/ip by using CIFS(common internet

file sharing) method

Linux uses SMBD/NMBD to share file and folders with windows machine

for this we have to configure samba server on linux machine

pakages samba,samba-common,samba-client,swat

portno. 137 NetBIOS name service

138 NetBIOS datagram service

139 NetBIOS session service

configuration file /etc/samba/smb.conf and /etc/samba/smbpasswd

service smb

Daemon smbd,nmbd


1 install the pakages if not already installed

# yum install samba*

2 open main configuration file

# vi /etc/samba/smb.conf

go to last line

copy last 8 lines(press yy)

paste at the bottom of file (press p)

now edit last 8 lines by removing ;(comment)

[myshare] .......... this is share name

comment = This is CMS shared dirctory .... you can type any comment

path = /var/share ................ this is path of shared directory

valid users = user1 ............... space seprated list of users

public = no .................... to make folder visible to all

writable = yes .................. to give write permission on folder

browseable = yes .... to see icon of shared folder in my'network places'

3 create your shared dirctory

# cd /var

# mkdir share

# cd share

# touch file1 file2 file3

4 start the service

# service smb restart

Client Side configuration:-

there are 2 methods in which we can access samba server from linux client

NFS:-

# mount /// -o

username=smbusername

# mount //192.168.1.10/myshare /mnt -o username=user1

FTP method:-

# smbclient /// -U username

# smbclient //192.168.1.10/myshare -U user1

smb>ls

smb>get file1

smb>put anyfile

smb>quit

Note :- on samba server you must create user and provide smb password

# useradd user1

# smbpasswd -a user1

*****

*****

to access samba server in graphical mode in linux go to

places----> Network Servers--------> system name

here you will find shared folder

How to access samba server from windows machine:-

go to my network places

entire network..... find linux machine icon

here you will find shared folder

..............................................................................

BOOTING PROCESS of LINUX

1 POST=== POWER ON SELF TEST

to check the conectivity of necessary hardware.

2 BIOS=== BASIC INPUT OUTPUT SYSTEM

to identify boot device

3 MBR==== MASTER BOOT RECORD

it is first 512bytes of hard disk

it keeps the information of boot loader(GRUB)

4 GRUB=== GRAND UNIFIED BOOT LOADER

GRUB is default boot loader for linux machine

it is loaded into memory(RAM) by MBR

it is capable of reading ext3 partition directly

GRUB is having 2 stages:-

1 STAGE

it loads second stage loader

2 STAGE

it reads /boot/grub/grub.conf file

and loads kernel(vmlinuz), and initrd

(Initial Ram Disk)

vmlinuz file is kernel of redhat linux

it is heart of operating system

it is responsible for establishing link between system

hardware and shell

then kernel loads initrd

initrd loads device drivers so that kernel can

comunicate with hardware.

5 INIT=== INITIALIZATION OF OTHER PROCESS

then kernel initialize first process that is init

init is responsible for running other process, like

auditd, syslog, portmap, cups, sshd, xinetd, vsftpd,

dhcpd, crond, atd, yum-updatesd, haldaemon.

all these deamons are inside /etc/init.d directory

6 Boot specific files:-

/etc/rc.d/rc.sysinit

/etc/rc.d/rc.local

/etc/inittab.... to define default runlevel

...to define prefdm(preffered display mangager)

.bashrc ..... inside user's home directory

..... to define user specific aliases

ex. alias vi=vim

7 Login prompt and after that if it is runlevel 5 then X11 server

is started and gdm/kdm/xdm will provide graphical desktop.

PROCESS MANAGEMENT:-

How to manage different process:-

system identifies any process by its process id(PID)

how to see pid of a running process:-

# service vsftpd status

vsftpd is runnig (3954).......

(this is pid)

or

# ps -ef | grep vsftpd

NOte:- PID for init is always 1

how to start any process(daemon)

# service vsftpd start

how to stop a process

# service vsftpd stop

how to restart any process


how to reload the process

# service vsftpd reload

when we restart the service is shutdown and again started, it takes time

when we reload service only changes are reloaded, it is fast

if any service is not responding then we can use kill command to

abnormally terminate that process:-

# kill

# kill 3954

note :- first check the pid of process, then kill it.

how to make any process to run permanently in any runlevel?

chkconfig command is used

like,

# chkconfig vsftpd on

to make vsftpd run bydefault in all possible runlevels

# chkconfig --level 35 vsftpd on

to make vsftpd run bydefault in runlevel 3 and 5 only

# chkconfig --list | grep vsftpd

to see present on/off status of vsftpd service

# chkconfig vsftpd off

to turnoff vsftpd service in all possible runlevels

..............................................................................

DHCP---- DYNAMIC HOST CONFIGURATION PROTOCOL

pakage dhcp-3.0.5-3.el5

configuration file /etc/dhcpd.conf

/usr/share/doc/dhcp-3.0.5/dhcpd.conf.sample

/var/lib/dhcpd/dhcpd.leases

port no.67 bootp server

68 bootp client

service dhcpd

Daemon dhcpd

How to configure dhcp server:-

check for dhcp pakage install:-

# rpm -q dhcp

if it is not installed then install it:-

# yum install dhcp*

now copy sample file to main configuration file:-

# cp /usr/share/doc/dhcp*/dhcpd.conf.sample /etc/dhcpd.conf

source sample file target main file

edit main configuration file

# vi /etc/dhcpd.conf

define the subnet with its class if ip addr

go to line no. 21

range dynamic-bootp 192.168.1.128 192.168.1.254;

start range end range

save and exit

restart the service:-

# service dhcpd restart

on client side issue following command to obtain ip addr automatically

from dhcp server:-

# dhclient

or

# netconfig

yes

* use dynamic IP configuration[bootp/dhcp]

then restart the service


or

user graphical method

# system-config-network

or

# neat

check the new ip addr

# ifconfig eth0

How to give DHCP reservation:-

we can bind any MAC addr to a IP addr by using dhcp ip address reservation

first we have to find out the mac addr of client:-

# ifconfig

it will show harware addr

now on dhcp server open main configuration file:-

# vi /etc/dhcpd.conf

modify following lines:-

hardware ethernet 12:34:56:78:AB:CD;

fixed-address 192.168.1.150;

save and exit, then restart dhcp service

note:- if you want to see mac addr of client from server machine then

# ping 192.168.1.X

# arp -a (press enter)

...............................................................................

14/04/08

DNS--- Domain Name Server/Service

DNS server is used to resolve Hostname to IP addr and IP addr to Hostname

DNS server maintains Zone files

Zonefiles are database which contains information about different server

and thier corresponding ip addr

there are two type of zone database files:-

Forward Lookup Zone file:-

This file contain Hostname and corresponding IP add

It is used in Hostname to Ip addr resolution

Reverse Lookup Zone file:-

This file contain IP addr and corresponding Hostname

It is used in Ip addr to hostname resolution

When Hostname is added to Domain name it becomes FQDN

sys10.cms.com.

sys10-- hostname

cms-- domain name

.com-- top level domain

. root domain

A DNS server will have following records:-

SOA record Start Of Authority record

First record created when a dns is configured

Used for defining replication between DNS and Bakup DNS

A Address record

Used to show it Ip Addr of any hostname

PTR Pointer record

Used to show hostname of any IP Addr

NS Name Server record

Used to identify nameserver(dns server)

CNAME Canonical Name record

Used to provid alias/duplicate names to server

MX Mail Exchange record

Used to identify Mail server

There are two types of DNS servers:-

Master and Slave

Master is having all zone records, its SOA no. is always greater than

Slave.

Slave is having backup of zone records of Master server, when any new

entry is entered in master server's zone file, it is automatically

replicated to slave, its SOA no. is always smaller than Master

How to configure Master DNS in Linux:-

pakages bind* caching-nameserver*

portno. 53

main conf file /etc/named.rfc1912.zone

/etc/named.caching-nameserver.conf

Service named

Daemon named

Note:- DNS works on BIND(Berkely Internet Name Domain) version 9

In RHEL we call bind as named(nameserver daemon)

Steps:-

check ip addr:-

# ifconfig

if it is not correct set ip addr

# neat

or

# netconfig

restart network service:-


check hostname

# hostname

if it is not correct then set hostname

# hostname sysX.cms.com

make it permanent:-

# vi /etc/hosts

192.168.1.X sysX.cms.com sysX


hostname=sysX.cms.com

now logout and login again to check hostname

check for pakage:-

# yum list installed bind*

if it is not installed, then install it:

# yum install cach*

# yum install bind*

total 9 pakages

edit configuration files:-

# vi /etc/named.caching-nameserver.conf

listen-on port 53 { 127.0.0.1;192.168.1.10; };

allow-query { localhost;192.168.1.0/24; };

match-clients { localhost;192.168.1.0/24; };

# vi /etc/named.rfc1912.zones

copy line no. 21 to 31 ( 11 lines)

paste it below line no. 31

edit these lines:

zone "cms.com" IN {

type master;

file "cms.for";

};

zone "1.168.192.in-addr.arpa" IN {

type master;

file "cms.rev";

};

change directory:-

# cd /var/named/chroot/var/named

copy and rename file localhost.zone

# cp -p localhost.zone cms.for

copy and rename file named.local

# cp -p named.local cms.rev

modify zone database file:-

# vi cms.for

$TTL 86400

@ IN SOA sys10.cms.com. root.cms.com. (

42 ; serial (d. adams)

3H ; refresh

15M ; retry

1W ; expiry

1D ) ; minimum

IN NS sys10.cms.com.

IN A 127.0.0.1

sys10.cms.com. IN A 192.168.1.10

sys9.cms.com. IN A 192.168.1.9

sys2.cms.com. IN A 192.168.1.2

# vi cms.rev

$TTL 86400

@ IN SOA sys10.cms.com. root.localhost. (

1997022700 ; Serial

28800 ; Refresh

14400 ; Retry

3600000 ; Expire

86400 ) ; Minimum

IN NS sys10.cms.com.

10 IN PTR sys10.cms.com.



open resolv.conf file and enter the ip addr of dns server

this file is similar to prefered dns of windows os

# vi /etc/resolv.conf

nameserver 192.168.1.10

now restart service:-

# service named restart

client side configuration:-

provide the ip addr of dns server in relov.conf file(preffered dns)


nameserver 192.168.1.10

query dns server and check the output:-

we can check dns server by two commands:-

nslookup and dig

# nslookup

enter the server name

the output will be ip addr of server

# dig sys10.cms.com.

or

# dig -x 192.168.1.10

................................................................................

KICKSTART INSTALLATION

It is similar to RIS/Unattended installation of Windows os

By using kickstart installation we can install linux on remote machine

all the installation files are present on kickstart server

client is booted from linux bootable cd(cd no.1) and

then it will take installation files from server along with

answer file.

Answer file is a file genereted on kickstart server which provides all

answers of questions which are asked during installation process.

Requirements for kickstart server:-

all the files of RHEL cd/dvd

dhcp server

kickstart answer file

nfs/ftp server

Requirements for kickstart client:-

first cd/dvd of RHEL

How to configure kickstart server:-

first configure your system as dhcp server, providing valid ip addr range

method 1:-

if we are using 5 cds then, copy all the contents of 1st cd to

/var/ftp/pub

then copy contents of Server dir of remaining cds to /var/ftp/pub/Server

method 2:-

if we are using 1dvd then simply copy complete dvd to /var/ftp/pub

now configure nfs server to share this location

# vi /etc/exports

/var/ftp/pub *(rw,sync)


check it

# showmount -e

or

now configure ftp server to share this location

just install the vsftpd pakage and configuration is completed

because bydefault ftp server shares /var/ftp/pub location itself


now create kickstart file:-

for this we need a pakage system-config-kickstart

if this pakage is not installed then install it first form cd/dvd/yum

then

# system-config-kickstart(press enter)

it will open a wizard

configure the options,

after configuring options you have to add pakage list manually to the

kickstart file

give follwing command:-

# yum grouplist >> /var/ftp/pub/ks.cfg

it will transfer all group names to end of kickstart file

now modify that file

# vi /var/ftp/pub/ks.cfg

at the bottom write

%pakages

@ editors

@ Java Development

....

....

then save the file

give executable permission to this file:-

# chmod +x /var/ftp/pub/ks.cfg

so that any client can execute this file when needed

How to configure kickstart client:-

boot the system by using 1cd

you will get boot prompt

boot:

here you can use any method nfs/ftp

boot: linux ks=nfs:192.168.1.10:/var/ftp/pub/ks.cfg

or

boot: linux ks=ftp://192.168.1.10/pub/ks.cfg

installation starts from server........

...............................................................................

How to perform network installation:-

configure nfs/ftp server with dump of all cds in /var/ftp/pub

on the client side boot with cd

boot: linux askmethod

it will ask for type of intallation

nfs

ftp

cdrom

choose nfs and specify ip addr of nfs server and dir(/var/ftp/pub)

or

choose ftp and specify ip addr of ftp server and dir(/var/ftp/pub)

installation starts from server........

...............................................................................

MAIL SERVER:-

MAIL server uses MTA( mail transfer agent) like sendmail, qmail, postfix

squirrelmail, smail etc

MTA uses SMTP protocol to send and recieve mail at port no. 25

on the client side mail client software like mutt(Mutt Mail User agenT), thunderbird, evolution, and webmail

are used to send and recieve mail.

How to configure Mail server(sendmail):-

pakages sendmail* m4*

portno. 25 SMTP

110 POP3

143 IMAP

config file /etc/mail/sendmail.mc

/etc/mail/sendmail.cf

service sendmail

daemon sendmail


install the pakages if not already installed

# yum remove sendmail*

# yum install sendmail*

open main configuration file:-

# vi /etc/mail/sendmail.mc

edit following line no.

116 add "# dnl" at the begining of line

155 add "# dnl" at the begining of line

(delete to new line)

compile this file and send its contents to sendmail.cf file

# m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

note: this command will not show any output on screen

m4 is a macro compiler which is used to compile sendmail.mc file

start service

# service sendmail restart

set hostname ......... mail.cms.com

set ip addr

on client side:-

set hostname............. sysX.cms.com

set ip addr

set ip addr of dns server in resolv.conf file


nameserver 192.168.1.X

DNS Server configuration:-

In dns server the only change is in forward lookup zone file:-

add following entry:-

IN MX 5 mail.cms.com.----(to define mail server)

192.168.1.X IN A mail.cms.com.----(to define its ip addr)

now start mailing from one user to other

root user is mailing to user1:-

# mail user1

Subjet: hi

skldjf;lasjkdf

lkjdslkafja;sldjkf

these are the contents of mail

type it and then press ctrl+d

Cc: (press enter)

mail is sent to user1

how to check mail:

Login as different user, user1

$ mutt (press enter)

or

$ mail (press enter)

How to configure squirrel mail( graphical mode )

Install following pakages:

squirrelmail*, dovecot*, php*, perl*, httpd*, curl*, cyrus-imapd*,

and sendmail* if it is not already installed

Restart following services:

service httpd restart

service dovecot restart

service cyrus-imapd restart

service saslauthd restart

service sendmail restart

Then you can access mail in graphical mode using webmail( mail client )

open mozila firefox web browser

type following addr

http:///webmail

like

http://mail.rhce.com/webmail

it will ask for username and password

then you can access your mail

...............................................................................

17/04/08 WEB SERVER(APACHE SERVER)

There are many web servers like IIS(windows), apache, sunone, AOL, etc

most popular web server is Apache, it works on both windows and linux

more than 68% of total web servers of world are configured on Apache

Note:- go to www.netcraft.com

type url of any web server, and search, it will show you

on what kind of server that web site is working,

like www.way2sms.com is working on Apache 2.0 installed on Fedora8

go to ip2location.com

type url of any web server, and search, it will show you

the geographical location of that web server,

like www.google.com is in US, california, street...., contact person...

www.whois.net...... you can find who is maintaining that server,

complete contact information is displayed with ph. no. too

use nslookup command to see ip addr of any dns server.

How to configure web server:-

pakages httpd*(httpd,httpd-manaul,httpd-devel)

port no.80

conf file/etc/httpd/conf/httpd.conf

service httpd

daemon httpd

steps to configure web server:-

install the pakages if not already installed:-

# yum install httpd*

open main configuration file:-

# vi /etc/httpd/conf/httpd.conf

modify following lines:-

250 ServerAdmin [email protected]

264 ServerName www.cms.com.:80

280 DocumentRoot "/var/www/html"

134 Listen 80

390 DirectoryIndex index.html

line 250 is for providing contact user information

if your web server is not working then client will contact to

this person

line 264 is for provding url for your web site, it may be different from your system name

like here system name is web.cms.com

but website url is www.cms.com.

and it works on port no. 80

line 280 is for defining DocumentRoot

this is the location where your html files are kept

you can change this location

134 Listen 80

this is to define portno. that this web server listens

390 DirectoryIndex discribes the name of first page of your website

if first page name is different then change this option, by

default it is index.html file which is created inside

/var/www/html(DocumentRoot)

after editing configuration file you have to create website(index page)

# cd /var/www/html

# vi index.html

This is cms.com web site

This is home page of cms computers ltd.

This page is created by YOURNAME

now restart the service

# service httpd restart

now specify your dns server:



check it

# dig -x 192.168.1.X

DNS server side configuration:-

on the dns server there is only one change

open FLZ file and add the entry of web server;

web.cms.com. IN A 192.168.1.Y----to define webserver

www.cms.com. IN CNAME web.cms.com.---to define its aliasname

# service named restart

Client side configuration:-

define your preffered dns:-



now open web browser and open website www.cms.com or web.cms.com

...............................................................................

18/04/08

NIS..... Network Information Services

It is a centralised directory service through which we can share

resources like users, groups, mails over the network

It is similar to LDAP( Light Weight Dirctory Access Protocol )

Linux machine uses NIS, Solaris machine also uses NIS+

How to configure NIS server?

pakages ypserve*, ypbind*, yp-tools*

ypserve is for NIS server only, not client side

ypbind and yp-tools are required on client side

ypbind pakage is used to bind nis-client with server

portno. randomly assigned by portmap service

to see portno. use command--- (rpcinfo -p)

conf file/var/yp/Makefile

/etc/sysconfig/network

service yppasswdd, ypserv, portmap

daemon yppasswdd

steps:-

1 install the pakage ( remove it if it is already installed )

# yum remove yp*

# yum install yp*

2 set nis domain name temporarily

# nisdomainname cms.com

check it

# nisdomainname (press enter)

3 set nis domain name permanently


NETWORKING=yes

HOSTNAME=sysX.cms.com

NISDOMAIN=cms.com

4 edit main conf file

# vi /var/yp/Makefile

line no. 23

NOPUSH=TRUE

it means that there is no slave nis server

line no. 109

all: passwd group....... mail\

list of database which are centralised on network

5 create master nis server's database

# /usr/lib/yp/ypinit -m

it will ask hostname: (press ctrl + d)

then it will ask (y/n) (press y)

6 create some users:-

# useradd nisuser1

# passwd nisuser1

7 share your home dir using nfs server:

# vi /etc/exports

/home *(rw,sync)


# showmount -e

Configuring NIS-Client:

1 set nisdomain name

# nisdomainname cms.com


NISDOMAIN=cms.com

2 mount home dir from server over client's home dir

# mount 192.168.1.X:/home /home

3 specify the type of authorization:

# authconfig-tui

* nis

ok

4 check your nis server conectivity

# ypwhich

it will show nis domain name in output

5 logout and login with nisuser1

now whatever data you create on client machine's home dir

will be stored on nis-server's home dir

it means /home dir is centralized

..............................................................................

SHELL SCRIPTING

# grep 'root' /etc/passwd

# date --help | grep year

# cut -d: -f1 /etc/passwd

# grep bash /etc/passwd | sort

# cut -d: -f7 /etc/passwd | sort | uniq

first shell script:-

# vi first.sh

#/bin/bash

echo " this is my first shell script "

echo " Enter your First name:.......... "

read firstname

echo " Enter your Last name:........... "

read lastname

echo " Your Full Name Is :............. $firstname $lastname "

save this file and give execute permission

now to run this shell script :

# ./first.sh

or

# bash first.sh

second shell script:-

# vi second.sh

#/bin/bash

echo "enter yes or no"

read ans

ans="$(echo $ans | tr 'A-Z' 'a-z')"

echo "$ans"

save the file and give execute permission

now run shell script:

# ./second.sh

Note:- tr means translate character

used to translate characters

sed means Stream EDitor

used to edit output, without effecting original file

# vi pets

hi this is my pet animals file

i have a lot of pet animals

like

cat dog parrot and rabbit

but my fav. is cat

my cat is very soft

cat is white in color

dog is black in color

save the file and exit

# sed 's/cat/dog/' pets

this command will show edited output

all cat will be converted to dog in output

but the file will remain uneffected

# grep '^root:' /etc/passwd

to filter info of root user only

echo " this is date and time $(date)"

echo "pwd is : $(pwd)"

if [ -d $1 ]

then

echo " $1 is a dir"

else

if [ -f $1 ]

then

more $1

fi

fi

capital=dehli

echo "what is capital of india"

read cap

if [ $cap != $capital ]

then

echo "wrong"

exit 1

else

echo " correct "

fi

echo " enter ur weight"

read wt

if [ $wt -lt 500 ]

then

echo " u r eligible for next fight"

else

echo " u r not eligible for next fight"

read a

read b

c=`expr $a + $b`

echo $c

for x in 10 20 30

do

echo $x

done

cat > animal

cat

dog

fly

goat

lion

for i in `cat animal`

do

echo " $i"

done

...............................................................................

/etc/fstab and /etc/mtab files

FSTAB---- File System Table file stores information about partition,

file type, mount point, and mounting options

system reads this file at the time of booting, and mounts the partitions

which are listed in this file

common contents of /etc/fstab are:

LABEL=/ / ext3 defaults 1 1

LABEL=/boot /boot ext3 defaults 1 2

LABEL=/home /home ext3 defaults 1 2

LABEL=/usr /usr ext3 defaults 1 2

LABEL=/var /var ext3 defaults 1 2

LABEL=SWAP-hda7 swap swap defaults 0 0

/dev/hda9 /mnt ext3 defaults 0 0

label of partition mnt pt filesystem options dump fsck

how to see label of partition:-

# e2label /dev/hda2

/boot........ this is the label of /dev/hda2 partition

/etc/mtab..... MOUNT TABLE

this file provides system the iformation about mounted partitions

" mount " command uses the contents of this file

Note:-

when we mount any partition by using 'mount' command, then

/etc/mtab file is updated and new entry is added

but this type of mounting is temporary

after rebooting the system it is automatically unmounted

so to mount a partition permanently we use /etc/fstab file

we have to manually edit this file to mount a partition permanently

ex.

a new partition is created /dev/hda9, it is formated

to mount it temporarily,

# mount /dev/hda9 /mnt

to mount it permanently,

# vi /etc/fstab

at the bottom of this file type following line

/dev/hda9 /mnt ext3 defaults 0 0

or you can change mounting options

/dev/hda9 /mnt ext3 defaults,usrquota 1 2

................................................................................

Task Automation by using 'cron' and 'at'

cron daemon is used to automate any task,

by using cron daemon we can run any task in background on particular

date and time, this is similar to schedule task of windows

main configuration file is /etc/crontab

daemon name is crond

to add a new task :-

# crontab -e

this will open a blank file,

it is having following fields:

min hr date month day of week task(command)

05 15 24 04 * mkdir /root/auto

this task is to create "auto" dir in /root at 03:05pm on 24/04/08

the task will be completed in background

to restart cron service:

# service crond restart

to see current pending task:-

# crontab -l

to remove any task:-

# crontab -r

at

this command is used to schedule task for one time only:

# at 13:30

at> touch /root/breaktime

at> (press ctrl+d to save)

how to check it

# atq

it will diplay task no. and time

how to remove any task :

# atrm < task no.>

ex.

# at 13:29

at> eject

at> ctrl+d

# at 13:30

at> eject -t

at> ctrl+d

# at 13:31

at> eject

at> ctrl+d

check task list:

# atq

2

3

4

remove any particular task

# atrm 4

...............................................................................

Virtualization

Red Hat Virtualization can host multiple guest operating systems.

Each guest operating system runs in its own domain.

Each guest operating systems handles its own applications.

Virtualization is of two types:

Full virtualization or paravirtualization.

Full virtualization provides total abstraction of the underlying physical system

and creates a new virtual system in which the guest operating systems can run.

No modifications are needed in the guest OS or application

(the guest OS or application is not aware of the virtualized environment

and runs normally).

Paravirualization requires user modification of the guest operating systems

that run on the virtual machines(these guest operating systems are aware that

they are running on a virtual machine)

The first domain, known as domain0 (dom0), is automatically created

when you boot the system. Domain0 will host Guest OS(Domain1).

The hypervisor (Red Hat's Virtual Machine Monitor) is a virtualization platform

that allows multiple operating systems to run on a single host simultaneously

within a full virtualization environment.

A guest is an operating system (OS) that runs on a virtual machine in addition to

the host or main OS.

Hardware Requirements for Virtualization:-

Intel VT-x or AMD-V Pacifica and Vanderpool technology for full and paravirtualization.

For full virtualization your system must support PAE(physical Address Extension),

by using PAE technology we can increase the amount of physical or virtual memory

avialable to user applications.

Celeron " Pentium II " Pentium III " Pentium IV " Xeon " AMD Athlon " AMD Duron

for paravirtualization.

Installing virtualization:-

yum install

pakages are:

kernel-xen

xen

xen-libs

virt-managerz

gnome-applet-vm

libvirt

Booting a guest domain

we can use virsh or xm commands

# xm create -c guestdomainname

you can make it permanent :

# chkconfig xendomains on

Connect to a domian:

# xm console domain-id

Create a domain:

# xm create -c newdomainname

saving a domain:

# xm save domain-id

destroy a domain:

# xm destroy domain-id

shutdown a domain:

# xm shutdown domain-id

restore a domain:

# xm restore domain-id

suspend a domain:

# xm suspend domain-id

resume a domain:

# xm resume domain-id

reboot a domain:

# xm reboot domain-id

pause a domain:

# xm pause domain-id

unpause a domain:

# xm unpause domain-id

display domain states:

# xm list domain-id

diplay uptime:

# xm uptime domain-id

diplay domain information:

# xm domain info

Managing Virtual Machines in GUI mode:

by using Virtual Machine Manager

The Virtual Machine Manager (VMM) gives you a graphical view of the virtual machines

on your system.

You can use VMM to define both para-virtual and full virtual machines.

Open connection window:

go to applications ->system tools -> vitrual machince manager

select local xen host

click on connect

VMM window opens, here you can see domain0 is running

How to create a new virtual machine:

requirements:

first create a new partition on Domain0 host(ex. /dev/hda9)

then configure your nfs install server 192.168.1.10(share dir is /var/ftp/pub)

then create a kickstart server 192.168.1.10(save file in /var/ftp/pub)

click on new in VMM window

->forward

->enter the name of virtual server(remember this name) and click forward

->specify the type of virtualization(paravirtualization) and click forward

->enter intall media url........ nfs:192.168.1.10:/var/ftp/pub

enter kickstart url........... nfs:192.168.1.10:/var/ftp/pub/ks.cfg

click on forward

->specify the partition name

partition..... /dev/hda9

click on forward

->set max. memory for virtual machine( dont modify anything )

click on forward

->start creating virtual machine.............

after virtual machine is created you can view graphical mode in

virtual machine console window

to start your guest machine:-

# xm create -c guestname

then right click on guest in virtual machine manager and chose open to open

virtual console

Note:- you can also use "virt-install" command to create a virtual machine in

text mode

...............................................................................

PROXY SERVER

Proxy server is used to provide following three services:

Caching Server

Securing web access

Internet connection sharing

How to configure Proxy server:-

pakage squid*

portno. 3128

conf file/etc/squid/squid.conf

service squid

daemon squid

Server side configuration:

Install the pakage:

# yum install squid*

Open main configuration file:

# vi /etc/squid/squid.conf

line no.

73 http_port 3128

remove the hash from line no. 993

cache_dir ufs /var/spool/squid 100 16 256

define acl before line no. 2394

like

acl neighbours src 192.168.10.0/24

acl denydomain dstdomain .yahoo.com

acl denykeyword url_regex http://www.google.co.in

after defining all acl define allow/deny policy for each of them

below line no. 2500

like

http_access deny denydomain

http_access deny denykeyword

or

http_access deny denydomain denykeyword

http_access allow neighbours

save & exit

restart the service

# service squid restart

Client side configuration:

open mozilla fire fox

edit-> pref -> connections -> manual proxy ->

ip addr of proxy server and port no.(3128)

use same proxy server for all services

close

try to access different web sites.......

or for text mode

open elinks

press escape

go to setup menu

options manager

select protocols(press space to expand)

select http (press space to expand)

select proxy configuration(press space to expand)

select host and port-numbar option and edit

now specify ip addr of proxy server and portno.

save and exit

for windows clients:

open internet explorer

tools-> internet options-> connections -> lan connections ->

specif

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