Red Hat Linux Enterprise 5

Trainer - Mohammed Usman Sharieff

Unix - AT & T, Bell labs

HP Unix - HPAIX Unix - IBM

Solaris 10 – SUNFree or open source code -LINUX

Flavours of Linux

SuSe Caldera

Mandrake Fedora

RedHat - most popular

OS

Kernel – Core of the operating systemInteracts with hardware

Shell - bash shell ; command mode user interface

X windows system - GUI

Run levels: different modes in which the OS can be booted

Init 0 shutdownInit 1 single user modeInit 2 multi user Init 3 multi user with networkingInit 4 un usedInit 5 multi user with networking

and GUI ( X windows system)Init 6 restart

Understanding devices in Linux

/dev/hda h for ide device/dev/sda s for sata device

hda – a for primary masterhdb - b for primary slavehdc - c for secondary msterhdd - d for secondary slave

Numbering of the partitions

Primary /dev/hda1/dev/hda2/dev/hda3

Extended /dev/hda4

Logical /dev/hda5/dev/hda6/dev/hda7and so on….

Partitions required to install the RedHat Linux Enterprise 5

/boot 100MB /dev/hda1/ 5GB or greater /dev/hda2/swap 2 times of RAM /dev/hda3

/home home directory for users /dev/hda5

Root refers to……

/ slash or root directory that contains the OS

Root also refers to root user (administrator)

$ normal user prompt# root user prompt

Basic commands

ls ls-l date time clear man cd pwd

cp mv mkdir rm rmdir rm –r

vi filename touch filename gedit filename cat filename

useradd userdel passwd username head filename

more filename less filename ls-l>abc tail filename

su username su (for root) who whoami

hostname df –h df -T fdisk -l ifconfig -a

Working with HDD

1. fdisk – for partitioningfdisk /dev/hda

2. mkfs – for formatingcreating the file system (ext2 or ext3)

mkfs /dev/hda5

3. mounting : to make it accessible under the /mount /dev/hda5 /apps

Any partition or drive that needs to be accessibleHas to be mounted under the / . So create a folder under /For this partition or drive and mount it under that folder.

/etc directorycontains configuration files

/etc/inittab to change the run levels during boot

/etc/fstab for mounting partitions during boot

HDD partitionsFdisk /dev/hdaMkfs /dev/hda5 (ext 2)

Mkfs.ext3 /dev/hda5Mkfs –t ext3 /dev/hda5

e2label /dev/hda5 /dataMkdir /dataMount /dev/hda5 /data

Vi /etc/fstab

LABEL=/data /data ext3 defaults 1 2or /dev/hda5 /data ext3 defaults 1 2

Blkid Blkid /dev/hda5

Boot ProcessAfter Power on , POST , CMOS Setup, boot seq – HDD, MBR;GRUB …………………./boot contains boot loader, kernel and init

Boot loader – GRUBKernel and driversProcess – first process is Init /etc/rc.d/rc.sysinit

/etc/inittab /etc/rc.d/rc5.d/files K for kill scripts and s for start scripts

all files are linked to /init.d

Volumesfdisk –lfdisk /dev/sdanst cylend cyl: 100MBtpart no 10code; 8ewreboot

fdisk –l create 11th partition

fdisk /dev/sdanst cylend cyl: 100MBwreboot

pvcreate /dev/sda11 /dev/sda12 /dev/sda13pvdisplayvgcreate pool1 dev/sda11 /dev/sda12 /dev/sda13vgdisplaylvcreate pool1 –L 150 -n datalvcreate pool1 –L 150 -n appslvdisplay

we need to format, mount and put entry in vi/etc/fstabdf -h

pvcreate /dev/sda6 /dev/sda7 /dev/sda8pvdisplay

vgcreate pool1 /dev/sda6 /dev/sda7 /dev/sda8vgdisplay

lvcreate pool1 –L 152 -n datalvcreate pool1 –L 148 -n appslvdisplay

mkfs –t ext3 /dev/pool1/datamkfs –t ext3 /dev/pool1/apps

mkdir /datamkdir /apps

Vi /etc/fstab/dev/pool1/data /data ext3 defaults 1 2/dev/pool1/apps /apps ext3 defaults 1 2

Create partitionConvert to physical volumevgextend pool1 /dev/sda15

Lvextend –L 1000 /dev/pool1/vol1

Previously vol1 was 600We have added 400

So to extend we have to giv e total 1000Then umount

Format and mount again

Swap partitionfdisk –lfdisk /dev/sdanStart cylEnd cyltPart noCode : 82w

partprobeor reboot

mkswap /dev/sda8swapon /dev/sda8vi /etc/fstab/dev/sda8 swap swap Defaults 0 0

swapon –sfree

Users and groupsUseradd userdel

groupadd groupdel

Usermod -G groupname username(adding users to the group)

Id username

File permissions : chmod

d rwx rwx rwxFile/dir user group others

r w x4 2 1

chmod 777 filename ( 7 for user, group, others) chmod 750 filename (rwx for user, rx for group

and none for others)

permissions

# chown username filename# chown : groupname filename# chown username : groupname filename

#chgrp groupname folder

Umask - 0022

First mention umask then create the files.

If Umask is 022 folder perm is 755

if umask is 022 file perm should be 755since no execute (-111) the perm is 644 for files

execute for folder means to list (ls)

Create directories, users and groups, give passwords to usersadd users to the groupgive permission for each folder to each groupdeny others access to the folders

mkdir sales mkdir itUseradd sales1 useradd it1Passwd sales1 passwd it1Groupadd sales groupadd it Usermod –G sales sales1 Usermod –G it it1Chgrp sales /data/sales chgrp it /data/itChmod 770 /data/sales chmod 770 /data/itChmod g+s /data/sales chmod g+s /data/it

rpm rpm –ivh package rpm –U package… rpm - F package….

rpm –e (uninstall) (without .rpm)

yum install package (online) Yum upgrade package

Rpm –qa rpm –q sambaFrom CD to /usr/src/redhat

# bzip2 filename # gzip filename# bzip2 –d filename #gzip –d filename

(-d decompress)

mv a .a (creating hidden file)ls –all (listing hidden files also)

ln (copy and link)

mkdir /data1mkdir /data2Cd data1, vi exln ex /data2/ex

Networkingifconfig –a Unix OSIpconfig/all MS WindowsNetconfig Novell netware

Ifconfig eth0 up

ifconfiig eth0 10.0.0.10Ifconfig eth0 downservice network restart

vi /etc/sysconfig/network-scripts/ifcfg-eth0Change the ip esc :wq

service network restart

Services Service network restartService network stopService network startService iptables status

Service autofs status/etc/sysconfig/autofs

chkconfig autofs on (will tick the service in the tool system-config-services)

Nis – authentication (similar to ADS of MS or NDS of novell

nfs – sharing (between unix )

samba – (sharing between unix and MS pcs)

apache – web server (similar to IIS of MS)

bind – dns – named server

dhcp - (automatic configuration of ip, dg, dns)

ftp (file upload and download)

telnet (remote access)

nfs configuration on the Serverrpm –ivh nfs…..rpm

service nfs start

vi /etc/exports/data 10.0.0.0/255.0.0.0(rw,sync,no_root_squash)

exportfs –rv

service portmap restart service nfs restart

Chkconfig nfs on

Client configuration for nfs

vi /etc/fstab ipaddress : /data /data nfs defaults 0 0computername : /data /data nfs defaults 0 0

Example: srv1:/home /home nfs defaults 0 0

Vi /etc/hosts (if servername is used)ip computername

Basic commandsTAR tar cvf test.tar test

tar xvf test.tar

c-create x – extract f - file

Attributes : lsattr chattr

chattr +i filename (cannot delete or rename)

i-immutable

ls –R (list sub directories and files – tree )rm -r (remove all subdirec and files )rmdir for empty directories

cat /proc/cpuinfo

Piping - grepFind Locate

Grep name /etc/passwdEgrep

ps –e | moreEgrep : /etc/passwd |more

ls –l | more

Troubleshooting

Mount –o remount,rw /