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linux

InstallationInstallation

UninstallationUninstallation

SetupSetup

ConfigureConfigure

Basic CommandsBasic Commands

Advaced commandsAdvaced commands

Installation:

Linux - Any Linux distribution such as Ubuntu, Fedora, Redhat, OpenSuse etc.gathering system hardware information;

backing up your old system (optional, but strongly recommended)

preparing Linux partitions

deciding on a boot loader (for dual boot systems)

booting a Linux kernel

installing the kernel

Pre-configuration Set up

Linux allows you to choose a default language for you Operating System.

Select the appropriate mouse configuration.

Since this is a graphical mode of installation, the system usually probes for the mouse, and will select what it has found. If this is incorrect, simply select the correct configuration.

Select the keyboard setting you wish to use.

This menu allows the installer to choose from installing a GNOME, KDE, server or a custom workstation.

GNOME and KDE are similar to MS Windows, running over the Redhat OS.

Allows graphical interfaces instead of a command line interface.

Removing disk allow the system to manually partition your drive.

This will only use free or partitioned drives formatted to ext2.

Manually partition allows the user to manually set the partition size for each particular partition.

Setting Partitions

This systems has two 20 Gb drives, hda and hdb.

hda is the primary drive and hdb is the secondary drive.

hda has two partitions, one formatted to vfat32 and BSD/386, for windows and FreeBSD, respectively.

The entire hdb drive is used for Linux, and has four partitions, /boot, /home, /, and a swap.

Installing Networks:- Allows you to use a static IP address or get one from a DHCP server.

IP address: IP of local machine

Netmask: Sub netmask of local machine.

Network & Broadcast: will be set by the system after you entered the IP and Netmaks. Usually correct, if not, set to them accordingly

Hostname: This is the name of your local host. Make sure you include the domain name along with the hostname.

a:-

Gateway:This is the default gateway address where all traffic will leave. ie; to get outside the network.

Primary DNS: The IP or domain name of a Domain Name Server (DNS)

Secondary DNS: A second IP or domain name of a DNS server

Installing Software in Linux

rpm - Redhat Package Manager.

YUM - Package Manager which resolves dependency issues.

dpkg - Ubuntu tool performs same job as rpm.

apt-get - Package Manager in Ubuntu.

Compiling from source.

Uninstallation

"uninstall" Linux

LOCK C:

FDISK /MBR

Uninstall Commands:

get rid of LILO--it overwrites the master boot record (MBR

"lock" command allows

"raw" writing to disk, which is normally disallowed on more recent DOS versions as an antiviral measure

The problem with FDISK/MBR

proceed it with the "lock" command

a:-

After this Linux partitions using the DOS "FDISK" utility to re-claim the hard drive space.

may use linux fdisk

The simplest may be to boot from the Linux installation floppy/CD, and to remove the partition using the Linux partitioning tool when it pops up during the "installation" procedure

b:-

Linux-based solution. If you can boot Linux - say via boot floppy - you can simply invoke "dd":

dd if=/dev/zero of=/dev/hda bs=512 count=1

This fills up the MBR with zeros. Obviously, you have to be root to do this.

DOS-based solution . Boot with a DOS floppy that has "debug" on it; run

debug

c:- At the '-' prompt, "block-fill" a 512-byte chunk of

memory with zeroes:

f 9000:0 200 0

Start assembly mode with the 'a' command, and enter the following code:

mov dx,9000

mov es,dx

xor bx,bx

mov cx,0001

ready for partitioning and installation.

d:- mov dx,0080

mov ax,0301

int 13

int 20

Press <Enter> to exit assembly mode, take a deep breath - and press "g" to execute, then "q" to quit "debug". Your HD is now in a virgin state, and

SET UP:

TASK MANAGER

a:-

b:-

RESTART

SIZES

GRAPHICALLY

a:-

System Configuartion:

Configuring the correct time zone for your system.

If incorrect one is selected, this can be easily changed within Redhat after installation.

Configuring account information.

Use an appropriate root password, making sure it is not too short, and try using upper and lower case letters and characters.

Create users to avoid the system administrators to run non-root commands as root.

This is more a security issue.

HARDWARE CONFIGRATION: System will usually probe for a monitor.

Select the model of the monitor you are using if the system probes the incorrect model.

If you decide to use a generic monitor, make sure that the correct horizontal and vertical sync is entered, as this may cause harmful damages to the monitor itself.

a:-

The menu allows you to choose the video display card you are using for you system.

The system will probe and select a default, but that can be changed.

The configuration can be tested to verify that everything is configured accordingly by clicking on the “test the configuration” icon.

b:-

If everything is configured properly, the system will display a gray then green back ground followed by a menu instructing you on whether you can see the that test menu.

You can also customize the the X configurator.

The X configurator allows you to set the colour depth, and the resolution of the display.

There is also an option to use a graphical login screen. If this is not selected, the default is the text mode login screen.

Pre Installation is Configured:

This is the last chance to change any configuration before Redhat is installed.

If all configuration is correct, click “next” and installion will begin

INSTALLING PACKAGE'S

This is what you’ll see during installation.

This screen will display the number of packages being installed, number of packages installed, and the time remaining for installation.

When all the packages are all installed, a final screen will appear stating all packages have been install successfully.

Post-Install Configuration:

Reboot the system.

graphical login, simply type the user name followed by the password. When the password is verified, Xwindows will automatically start.

default text login will appear after boot up.

Type the user login followed by the password. At the prompt, type “startx” and this will start Xwindows.

BASIC COMMANDS: Creating an account.

Logging in.

Virtual consoles

Shells and commands

Logging out.

Changing your password.

Files and directories

The directory tree.

The current working directory.

Referring to home directories.

Linux Command Basic's

To execute a command, type its name and arguments at the command line

ls -l /etc

Command name

Argumen's

options

LOGGING IN

Connect to the Linux system using telnet:

vt100, vt220, vt320

ansi

tty

X-windows

Able to login more than once with same user

No ‘MW’ problems!

a:

Before you can use it you must login by specifying your account and password:

Linux 2.2.13 (penguinvm.princeton.edu) (ttyp1)

penguinvm login: arjunPassword:Last login: Tue Jan 4 10:13:13 from linuxtcp.princeton.edu[neale@penguinvm neale]$

Use the useradd command

Use the passwd command to set password

[root@penguinvm]# useradd scully[root@penguinvm]# passwd scullyChanging password for user scullyNew UNIX password:Retype new UNIX password:passwd: all authentication tokens updated successfully[root@penguinvm]#

Adding a New User

Limits on users can be controlled by

Quotas ulimit command

Authority levels for a user controlled by group membership

User's And Groups

Users are identified by user identifications (UIDs), each of which

is associated with an integer in the range of 0 to 4 294 967 295 (X’FFFFFFFF’). Users with UID=0 are given superuser privileges.

Users are placed in groups, identified by group identifications (GIDs). Each GID is associated with an integer in the range from 0 to 4 294 967 295

Let the system assign UID to avoid duplicates

Use id to display your user and group information

uid=500(neale) gid=500(neale) groups=500(neale),3(sys),4(adm)

TYPICAL GROUP SETUP

Sys

Bin

Adm

staff

New User

Now logoff using the exit command

login as the new user

Linux 2.2.13 (penguinvm.princeton.edu) (ttyp2)

penguinvm login: scullyPassword:[scully@penguinvm scully]$

U need Help!

The Linux equivalent of HELP is man (manual)

Use man -k <keyword> to find all commands with that keyword

Use man <command> to display help for that command

Output is presented a page at a time. Use b for to scroll backward, f or a space to scroll forward and q to quit

Linux File System Basic's

Directories

User home directories

Data files

root

Linux files are stored in a single rooted, hierarchical file system

Data files are stored in directories (folders)

Directories may be nested as deep as needed

Some Special File Names:

Some file names are special: / The root directory (not to be confused with the root user)

. The current directory

.. The parent (previous) directory

~ My home directory

Examples: ./a same as a

../jane/x go up one level then look in directory jane for x

Special Files:

/home - all users’ home directories are stored here

/bin, /usr/bin - system commands

/sbin, /usr/sbin - commands used by sysadmins

/etc - all sorts of configuration files

/var - logs, spool directories etc.

/dev - device files

/proc - special system files

FILE PERMISSION'S

Every user:

Has a uid (login name), gid (login group) and membership of a "groups" list:

The uid is who you are (name and number)

The gid is your initial “login group” you normally belong to

The groups list is the file groups you can access via group permissions

Editor's

People are fanatical about their editor

Several choices available:vi Standard UNIX editorthe XEDIT-like editorxedit X windows text editoremacs Extensible, Customizable Self-

Documenting Display Editorpico Simple display-oriented text editor nedit X windows Motif text editor

Command Options:

Command options allow you to control a command to a certain degree

Conventions:

Usually being with a single dash and are a single letter (“-l”)

Sometimes have double dashes followed by a keyword (“--help”)

Sometimes follow no pattern at all

Common Command's

pwd - print (display) the working directory

cd <dir> - change the current working directory to dir

ls - list the files in the current working directory

ls -l - list the files in the current working directory in long format

cp <fromfile> <tofile>

Copy from the <fromfile> to the <tofile>

mv <fromfile> <tofile>

Move/rename the <fromfile> to the <tofile>

rm <file>

Remove the file named <file>

a:

mkdir <newdir> Make a new directory called <newdir>

rmdir <dir> Remove an (empty) directory

Advanced Command's

who List who is currently logged on to the system

whoami Report what user you are logged on as

ps List your processes on the system

ps aux List all the processes on the system

echo “A string to be echoed” Echo a string (or list of arguments) to the terminal

a:

alias - used to tailor commands: alias erase=rm alias grep=”grep -i” ar - Maintain archive libraries: a collection of

files (usually object files which may be linked to a program, like a CMS TXTLIB)

ar -t libgdbm.a__.SYMDEFdbmopen.o

b;

grep - Searches files for one or more pattern arguments. It does plain string, basic regular expression, and extended regular expression searching

find ./ -name "*.c" | xargs grep -i "fork"

kill - sends a signal to a process or process group

You can only kill your own processes unless you are root

c:

# awk -F":" '{ print "username: " $1 "\t\tuid:" $3 }' /etc/passwd

Just add command :

For check ssh failure log ( in GNU/Linux Debian)

Code:

#/bin/cat /var/log/auth.log |grep sshd:auth |grep failure |awk '{print $1"-" $2 "-" $3 "-->" $12 "->" $14 "->" $15}'

2. Kill program one time click base keyword Code:

#for a in $( ps aux | grep "some-thing-text" | awk '{ print $2 }'); do kill $a; done;

exp ( klill crontab )Code:

d:

# cd /etc# for i in $(find -type f); do grep -iH nfsnobody $i; done

# grep -iH nfsnobody *

# awk '/ServerName/ {i=i+1} END {print i}' /etc/httpd/conf/httpd.conf

# grep ServerName /etc/httpd/conf/httpd.conf

# ipcs -s | grep apache | perl -e 'while (<STDIN>) { @a=split(/\s+/); print`ipcrm sem $a[1]`}'

# perl -e 'require Mail::SPF::Query'

Thank u