Tutorial Proggraming Free

tutorial - Head and Tail example

1. Suppose I need to read last 10 lines of a file
# tail -n 20 /var/log/boot.log

2. Suppose I need to read forst 10 lines of a file
# head -n 30 /etc/sensors.conf

Now imagine you want to follow what is been written “live” to the /var/log/messages file

# tail -f /var/log/messages

Free, facebook, tips, Links, blogging, Downloads, Google, facebookTips, money, news, apps, Social, Media, Website, Tricks, games, Android, software, PIctures, Internet, Security, Web, codes, Review, bloggers, SAMSUNG, Worldwide, Contest, Exitic, Phones, facebookTricks, hacking, London, Olympics, SEO, Youtube, iOS, Adsense, gadgets, iPHONE, widgets, Doodle, twitter, video, Deals, technology, Aircel, Airtel, iPAD, Angry, Birds, BSNL, TechLife, GMAIL, Idea, Microsoft, SmartPhones, Stress, Buster, Windows, Yahoo, Infolinks, Nokia, Scam, Uninor, browsers, Amazon, Euro, CUP, Chat, IDM, JOBS, Modem, Music, Reliance, Results, SSC, Tata, Docomo, bing, freebie, mobile, placements, AIEEE, AlertPay, Chrome, College, Competetive, Exam, Dehradun, Extension, FireFox, GPRS, HTC, IMPACT, Info, MTS, Mark, Zukerberg, Paypal, Promotional, Post, Torrent, UTU, Unlocking, VodaFone, Wall, Paper, apple, books, engineering, iCAR, iTunes, pinterest, rovio, AVG, Admit, Card, Adobe, Affiliate, Marketing, Akhilesh, Amul, Girl, BlackBerry, ChromeBook, Clixsense, Coupon, Digitallife, Discovery, Emoticons, Festival, GATE, GIMP, Income, Tax, International, JSS, JailBreaking, Kindle, Linux, Local, MAX, PAYNE, Mac, Mango, Memory, Speed, Nexus, Online, Shopping, Raakhi, Report, Rising, Stars, Sample, Science, Sony, Syllabus, TabletBooK, Teamviewer, Templates, Dark, Knight, Rises, USA, UPMT, Virgin, Xperia, ZTE, challan, counselling, course, btech, funny, iMOVE, registration

source:http://linuxpoison.blogspot.com/2008/05/13578175802937.html

tutorial - Journaled File Systems options

Journaled file systems write critical information about file system operations to a journal before actually modifying files. In the event of an unclean shutdown, the file system can be recovered more quickly by reading the journal instead of performing fsck. Journaling Options available in ext3

data=ordered - This is the default mode. Only meta data is journaled.
data=journaled - Meta data and data are journaled.
data=writeback - Not as good as “data=ordered”, but allows for a quicker fsck than standard ext2.

Converting from ext2 to ext3
Because of their close relation, it is fairly simple to upgrade from ext2 to ext3:
Modify file system type in /etc/fstab

Create the journal: tune2fs -j /dev/hda1

Make sure you fire mkinitrd command and create new initrd file for ext3 FS

source:http://linuxpoison.blogspot.com/2008/05/13578175806173.html

tutorial - Convert man pages to text

At the command line, run: man touch | col -b > filename.txt

Here’s what it means:

man = display the man pages for a stated command
| = pipe the output of the man pages somewhere else
col -b = format the output
> = send the output to a file
filename.txt = name of the file you wish to create and populate with output

source:http://linuxpoison.blogspot.com/2008/05/135781758014057.html

tutorial - Block messengers through Iptables

msn messenger user port 1863
yahoo messenger uses 5000,5010 and 5050

To block AOL IM and ICQ:

# iptables -A FORWARD –dport 5190 -j DROP
# iptables -A FORWARD -d login.oscar.aol.com -j DROP

To block MSN messenger:

# iptables -A FORWARD -p TCP –dport 1863 -j DROP
# iptables -A FORWARD -d 64.4.13.0/24 -j DROP

To block Yahoo messenger:

# iptables -A FORWARD -p TCP –dport 5000:5010 -j REJECT
# iptables -A FORWARD -d cs.yahoo.com -j REJECT
# iptables -A FORWARD -b scsa.yahoo.com -j REJECT

Note that this will only block clients on the computer itself. If you are using the computer as a router with NAT, you will want to use “-t nat -A PREROUTING” instead.

source:http://linuxpoison.blogspot.com/2008/05/135781758010061.html

tutorial - Installing and Using John the Ripper - Password cracker

Compile a source file
Download a source code from http://openwall.com/john/
Extract source files: tar xvzf john-1.7.0.2.tar.gz

1) cd john-1.7.0.2/src
2) Then we need to rum make command which will return a list of available systems that John the Ripper password cracker can be compiled on.
3) Choose your appropriate architecture, and compile: make linux-x86-any
4) Go and run the john the ripper binary:
cd ../run/
ls
./john
Using John the ripper:
For testing purposes you should create a testing user "johnripper" with password "password".

poison:~ # useradd johnripper
poison:~ # passwd johnripper
Changing password for johnripper.
New Password:
Reenter New Password:
Password changed.
poison:~ #

Time to Crack password:
John the Ripper's password cracker needs to access a shadow file in order to be able crack a password. You need to run "john" as superuser "root". Be sure that John Binary is in your path, or you are in directory where john Binary resides. Try and see how long it will take to crack your super secure password of: "password"

./john -users=johnripper /etc/shadow

source:http://linuxpoison.blogspot.com/2008/05/13578175804776.html

tutorial - Linux Filesystem Hierarchy

Here is a very cool and beautiful representation of the hierarchy which I found @linuxconfig.org site. The diagram below represents (part of) a Linux file system.

source:http://linuxpoison.blogspot.com/2008/05/135781758015306.html

tutorial - Video Players for Linux

MPlayer:

Mplayer for linux is a great movie player. MPlayer is well known for its wide format support and is known to support more multimedia formats than any other player. MPlayer easily plays MPEG/VOB, AVI, Ogg/OGM, VIVO, ASF/WMA/WMV, QT/MOV/MP4,RealMedia, Matroska, NUT, NuppelVideo, FLI, YUV4MPEG, FILM, RoQ, PVA files, supported by many native, XAnim, and Win32 DLLcodecs. With Mplayer, You can watch VideoCD, SVCD, DVD, 3ivx, DivX 3/4/5, WMV and even H.264 movies

Download Mplayer here

Xine:

xine is a free multimedia player. It plays back CDs, DVDs, and VCDs. It also decodes multimedia files like AVI, MOV, WMV, and MP3 from local disk drives, and displays multimedia streamed over the Internet. It interprets many of the most common multimedia formats available - and some of the most uncommon formats, too.

Download xine here

Kaffeine:

Kaffeine is another cool media player for KDE.

Kaffeine supports multiple player engines while its default engine is Xine. Kaffeine can easily keep track of multiple play lists simultaneously and give you the ability to auto load subtitles files when playing a certain video giving Kaffeine a wide variety of supported media types and letting Kaffeine access CDs, DVDs, and network streams easily. With the latest updates, Kaffeine is able to play nearly every known audio and video format, however some may only be played with proprietary codecs. Kaffeine features include streaming, DVB, DVD, Video CD and CD audio.

Download Kaffeine here

VLC for Linux:

VLC media player is a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, mp3, ogg, ...) as well as DVDs, VCDs, and various streaming protocols.
It can also be used as a server to stream in unicast or multicast in IPv4 or IPv6 on a high-bandwidth network.
It doesn't need any external codec or program to work.

Download VLC here

RealPlayer 11 for Linux:

Realplayer 11 for Linux is also something which a lot of people use to play more video, popular windows media files, real media filesand much more. With Realplayer you can create your personal playlists, control live streams and enjoy 5.1 surround sound (If you have good sound system)

Download Realplayer here

source:http://linuxpoison.blogspot.com/2008/05/135781758016110.html

tutorial - HowTo use scp and sftp commands

The scp command can be used to transfer files between machines over a secure, encrypted connection. It is similar to rcp. The general syntax to transfer a local file to a remote system is as follows:
scp username@hostname:/home/nikesh/log /tmp/log

The sftp utility can be used to open a secure, interactive FTP session. It is similar to ftp except that it uses a secure, encrypted connection. The general syntax is sftp username@hostname.com. Once authenticated, you can use a set of commands similar to those used by FTP

source:http://linuxpoison.blogspot.com/2008/05/135781758012612.html

tutorial - iftop - Network Usage by Connection

iftop displays network usage by connection. The default display shows the connection endpoints (port numbers may be toggled using the p key), with data transfer volumes displayed in numeric format and as a horizontal bargraph using reverse video. Various keys provide control over the display; pressing ? displays a help page listing these keys. iftop also provide command-line options for traffic filtering and interface selection.

The information displayed by iftop is detailed and easily understood. When an application is hogging your network bandwidth, iftop can be an invaluable tool -- though you may need to also use netstat -p to determine which process is behind a particular connection.

Installing from the command line: yum install iftop
Command: /usr/sbin/iftop
Upstream website: http://www.ex-parrot.com/~pdw/iftop/

source:http://linuxpoison.blogspot.com/2008/05/13578175808450.html

tutorial - Distributed memory object caching system

What is memcached?

memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.

Danga Interactive developed memcached to enhance the speed of LiveJournal.com, a site which was already doing 20 million+ dynamic page views per day for 1 million users with a bunch of webservers and a bunch of database servers. memcached dropped the database load to almost nothing, yielding faster page load times for users, better resource utilization, and faster access to the databases on a memcache miss.

How it Works

First, you start up the memcached daemon on as many spare machines as you have. The daemon has no configuration file, just a few command line options, only 3 or 4 of which you'll likely use:

# ./memcached -d -m 2048 -l 10.0.0.40 -p 11211

This starts memcached up as a daemon, using 2GB of memory, and listening on IP 10.0.0.40, port 11211. Because a 32-bit process can only address 4GB of virtual memory (usually significantly less, depending on your operating system), if you have a 32-bit server with 4-64GB of memory using PAE you can just run multiple processes on the machine, each using 2 or 3GB of memory.

read More ...

source:http://linuxpoison.blogspot.com/2008/05/13578175804556.html

tutorial - Change the splash screen color in Ubuntu

Originally a brownish color to match the Ubuntu theme, it does not quite fit with other themes and might want to be changed. Enter the gdm.conf file (sudo gedit /etc/gdm/gdm.conf). search the below lines in the file:

BackgroundColor=#dab082
GraphicalThemedColor=#dab082

Change it to what you like. For all black, use:

BackgroundColor=#000000
GraphicalThemedColor=#000000

source:http://linuxpoison.blogspot.com/2008/05/13578175806561.html

tutorial - How to enable Compiz Fusion in Ubuntu

In Ubuntu Hardy Heron, Compiz Fusion is already installed and is automatically enabled after you have installed your graphics' card drivers.

The only thing you have to do is to install the Compiz Configuration Settings Manager.

Open a terminal and type: sudo apt-get install compizconfig-settings-manager
After that navigate to: System --> Preferences --> Advanced Desktop Effects Settings

and there you may enable/disable any plugin you want.

source:http://linuxpoison.blogspot.com/2008/05/135781758010593.html

tutorial - Open Source Speech Recognition Engines

The Sphinx Group at Carnegie Mellon University is committed to releasing the long-time, DARPA-funded Sphinx projects widely, in order to stimulate the creation of speech-using tools and applications, and to advance the state of the art both directly in speech recognition, as well as in related areas including dialog systems and speech synthesis.

The CMU Sphinx project released a set of reasonably mature, world-class speech components that provide a basic level of technology to anyone interested in creating speech-using applications without the once-prohibitive initial investment cost in research and development; the same components are open to peer review by all researchers in the field, and are used for linguistic research as well.

Check it out : here

source:http://linuxpoison.blogspot.com/2008/05/13578175804585.html

tutorial - HowTo keep your Ubuntu up-to-date

It is important to have the system updated, so that we have all the latest patches, security fixes and packages upgrades from the repositories.

First, navigate to: System --> Administration --> Software Sources

and check that all repositories are enabled.

Then, open the terminal: Applications --> Accessories --> Terminal
and type: (you need to provide the password here)
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade

With this you are done with the system update.

source:http://linuxpoison.blogspot.com/2008/05/135781758012049.html

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