How to check disk fragmentation without using fsck

http://superuser.com/questions/474536/in-linux-how-do-you-check-if-a-disk-is-fragmented

#!/usr/bin/perl -w

#this script search for frag on a fs
use strict;

#number of files
my $files = 0;
#number of fragment
my $fragments = 0;
#number of fragmented files
my $fragfiles = 0;

#search fs for all file
open (FILES, '-|', "find '$ARGV[0]' -xdev -type f -print0");

$/ = "\0";

while (defined (my $file = <FILES>)) {
        open (FRAG, "-|", "filefrag", $file);
        my $res = <FRAG>;
        if ($res =~ m/.*:\s+(\d+) extents? found/) {
                my $fragment = $1;
                $fragments += $fragment;
                if ($fragment > 1) {
                        $fragfiles++;
                }
                $files++;
        } else {
                print ("$res : not understand for $file.\n");
        }
        close (FRAG);
}
close (FILES);

print ( $fragfiles / $files * 100 . "% non contiguous files, " . $fragments / $files . " average fragments.\n");

How to Install Telnet Server on CentOS/RHEL 6/5

http://tecadmin.net/install-telnet-server-on-centos-redhat/

Install Telnet Server

Telnet server is available under default yum repositories. Execute following command to install it

# yum install telnet-server

Enable Telnet Service

Telnet is an xinetd based service, First edit telnet xinetd configuration file /etc/xinetd.d/telnetand set disable to no.

service telnet
{
        flags           = REUSE
        socket_type     = stream
        wait            = no
        user            = root
        server          = /usr/sbin/in.telnetd
        log_on_failure  += USERID
        disable         = no
}

Now restart xinetd service

# service xinetd restart

How to install JDK on Redhat/CentOS usng the alternatives command

http://www.if-not-true-then-false.com/2010/install-sun-oracle-java-jdk-jre-7-on-fedora-centos-red-hat-rhel/

Install Java JDK or JRE package

## JDK 32-bit ##
rpm -Uvh /path/to/binary/jdk-7u67-linux-i586.rpm
 
## JDK 64-bit ##
rpm -Uvh /path/to/binary/jdk-7u67-linux-x64.rpm
 
## JRE 32-bit ##
rpm -Uvh /path/to/binary/jre-7u67-linux-i586.rpm
 
## JRE 64-bit ##
rpm -Uvh /path/to/binary/jre-7u67-linux-x64.rpm

Install Sun/Oracle JDK java, javaws, libjavaplugin.so (for Firefox/Mozilla) and javac with alternatives –install command

## java ##
alternatives --install /usr/bin/java java /usr/java/latest/jre/bin/java 200000
## javaws ##
alternatives --install /usr/bin/javaws javaws /usr/java/latest/jre/bin/javaws 200000
 
## Java Browser (Mozilla) Plugin 32-bit ##
alternatives --install /usr/lib/mozilla/plugins/libjavaplugin.so libjavaplugin.so /usr/java/latest/jre/lib/i386/libnpjp2.so 200000
 
## Java Browser (Mozilla) Plugin 64-bit ##
alternatives --install /usr/lib64/mozilla/plugins/libjavaplugin.so libjavaplugin.so.x86_64 /usr/java/latest/jre/lib/amd64/libnpjp2.so 200000
 
## Install javac only if you installed JDK (Java Development Kit) package ##
alternatives --install /usr/bin/javac javac /usr/java/latest/bin/javac 200000
alternatives --install /usr/bin/jar jar /usr/java/latest/bin/jar 200000

How to upgrade Docker on Ubuntu 14.04 ?

http://askubuntu.com/questions/472412/how-do-i-upgrade-docker
http://xmodulo.com/2014/05/manage-linux-containers-docker-ubuntu.html
http://xmodulo.com/2014/05/docker-containers-centos-fedora.html
https://fredjean.net/running-docker-under-linux-mint-16/

Suppose it is Ubuntu Trusty (14.04) release, which has 0.9.1 officially

Update to 0.11.1 release

If you want to upgrade in this release, see new launchpad https://launchpad.net/~docker-maint/+archive/testing, better use ppa installation.

sudo add-apt-repository ppa:docker-maint/testing
sudo apt-get update
sudo apt-get install docker.io

Now I get the latest one

$ docker -v
Docker version 0.11.1, build fb99f99

Be aware, with the 1.0 GA release, this method may be changed

Update to latest release(now 1.1.1)

This is the way stated to install docker for 12.04 LTS in official document and noticed inubuntuupdates.org, which looks work for 14.04 as well.

Refer the command to Getting Docker Installed on Ubuntu 12.04 LTS as well

$ wget -qO- https://get.docker.io/gpg | sudo apt-key add -
$ sudo sh -c "echo deb http://get.docker.io/ubuntu docker main > /etc/apt/sources.list.d/docker.list"
$ sudo apt-get update
$ sudo apt-get install lxc-docker

Now I get

$ docker -v
Docker version 1.1.1, build bd609d2

lxc-docker will remove old docker package, therefore please backup the configuration in advance.

Install GNU command line tools on Mac OSX

http://www.topbug.net/blog/2013/04/14/install-and-use-gnu-command-line-tools-in-mac-os-x/

Install Homebrew

First, visit Homebrew homepage and follow the installation instructions to install Homebrew.

Shortcut: install the latest XCode and then run the following command to install:

ruby -e "$(curl -fsSL https://raw.github.com/Homebrew/homebrew/go/install)"

Then add the following line to your .bashrc or .zshrc:

export PATH="$(brew --prefix coreutils)/libexec/gnubin:/usr/local/bin:$PATH"

Install the GNU Command Line Tools

First comes the most important one – GNU Coreutils:

brew install coreutils

GNU Coreutils contains the most essential UNIX commands, such as ls, cat.

AKKA 2.2.3 tutorial

http://www.reactive.io/tips/2014/03/28/getting-started-with-actor-based-programming-using-scala-and-akka/
http://roestenburg.agilesquad.com/2010/07/upgrading-to-akka-master-010-and-scala.html
 





http://saburi380.blogspot.com/2014/01/akka-223.html

It is the notes about how can you easily try on a single server, the Akka 2.2.3. ( Http://Akka.Io/ ) Akka 2.2.3 in CentOS6 on, + Java 7 a (OpenJDK) + scala 2.10. The multiple servers (three or 
four) example is, here .

How to configure static IP on CentOS

https://gist.github.com/fernandoaleman/2172388

## Configure eth0
#
# vi /etc/sysconfig/network-scripts/ifcfg-eth0
 
DEVICE="eth0"
NM_CONTROLLED="yes"
ONBOOT=yes
HWADDR=A4:BA:DB:37:F1:04
TYPE=Ethernet
BOOTPROTO=static
NAME="System eth0"
UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03
IPADDR=192.168.1.44
NETMASK=255.255.255.0
PREFIX=24
DNS1=208.67.222.222
DNS2=208.67.220.220
DNS3=208.67.222.220
HWADDR=00:24:7E:6D:C0:FB
GATEWAY=192.168.1.1
 
 
## Configure Default Gateway
#
# vi /etc/sysconfig/network
 
NETWORKING=yes
HOSTNAME=david-centos6
GATEWAY=192.168.1.1
 
 
## Restart Network Interface
#
 
/etc/init.d/network restart
 
## Configure DNS Server
#
# vi /etc/resolv.conf
 
nameserver 8.8.8.8 # Replace with your nameserver ip
nameserver 192.168.1.1 # Replace with your nameserver ip



Note: don't forget to modify /etc/hosts by adding a new entry for 192.168.1.44 and remove 127.0.0.1 (because 127.0.0.1 will result in Spark Master refuse the connection request from Spark Worker)

Change cygwin home directory

http://codeaweso.me/2011/07/change-cygwin-home-directory/

mkpasswd -l -p "$(cygpath -H)" > /etc/passwd

Shell tips

filename="all you need is love - the beatles.mp3"
ext=$(echo $filename | grep -o '\....$')
title=$(echo $filename | sed 's/ - .*//; s/\b\w/\u&/')
artist=$(echo $filename | sed "s/.* - \(.*\)$ext/\1/; s/\b\w/\u&/g")
echo $title - $artist$ext

All you need is love - The Beatles.mp3

How to install Groovy on ubuntu 10.10

http://www.code-republic.com/?p=12

note: Ubuntu uses /etc/environment to setup your environment variables

Remote assistance from Linux to Windows

http://superuser.com/questions/91156/remote-assistance-from-linux-to-windows

Top Things to do after installing Ubuntu

http://www.unixmen.com/top-things-to-do-after-installing-ubuntu-1104-natty-narwhal/

Ubuntu 12.04 LTS Precise Pangolin beta 1 is almost out. The final release it scheduled to be out in the 26th of April 2012. After you actually get done with the installation, there would likely exist a heap of things you still need to take care of. This post will share some interesting insight and ideas about what you can and should do after a successful installation.

How to install OpenJDK 7 in Ubuntu 12.04 ?
http://www.ubuntugeek.com/how-to-install-oracle-java-7-in-ubuntu-12-04.html

5 Things to do after installing Ubuntu 12.04

http://www.youtube.com/watch?v=2DDmMswem5E

Installing And Configuring ESXI 4.1 Free edition

http://www.youtube.com/watch?v=8Uh1mBsVGYo&feature=related

The movie clip shows you how to:
1. Install VMWare ESXi Free on VMWare Workstation
2. Install vSphere Client to manage/configure ESXi

A good introduction to the VMWare vSphere Hypervisor (type 1 and 2)
http://www.youtube.com/watch?v=HtNJD5cDpL8&feature=related

http://www.youtube.com/watch?v=ZBl1Tf2A4lA&feature=related

How to install new virtual machine (VM) to ESXi

http://www.youtube.com/watch?v=2wiUW2LY-Ws&feature=related

FAQ

http://www.vmware.com/products/vsphere-hypervisor/faq.html

Managing diskk usage with quotas

http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch28_:_Managing_Disk_Usage_with_Quotas

# who
# wall The system is shutting down now!

# init 1
# cat /etc/fstab | grep -w usrquota
(if not exist then add it to make it looks like below:)

LABEL=/home       /home          ext3    defaults,usrquota  1 2

# mount -o remount /home
# exit

# touch /home/aquota.user
# chmod 600 /home/aquota.user
# aquotacheck -vagum
# edquota -u mp3user

Disk quotas for user mp3user (uid 503):   Filesystem  blocks       soft       hard     inodes     soft     hard
/dev/hda3                                                 24          0          0          7        0        0


change the soft value to 5000 to limit user mp3user to a maximum of 5MB of data storage.

Configure LOPA to run on Ubuntu 10.10 (64-bit)

Install Flex SDK on Ubuntu 10.10 (64-bit):

http://www.philliphodges.co.uk/?p=435 (note: the adl in bin folder cannot be executed because the downloaded SDK is for Mac OSX not Linux, you need to download Linux version of AIR SDK from http://kb2.adobe.com/cps/853/cpsid_85304.html and copy the the Linux version adl over to /opt/flex/bin)

Install AIR SDK on Ubuntu 10.10 (64-bit):

http://www.jamesward.com/2010/10/14/install-adobe-air-on-64-bit-ubuntu-10-10/

Debug Configuration:

How To: Install Adobe AIR in 64-bit Linux Mint

http://forums.linuxmint.com/viewtopic.php?f=42&t=74523

How to setup GitHub on Ubuntu 10.10 ?

http://mr-greens.blogspot.com/2010/11/installing-git-in-ubuntu-1010-maveric.html

The following keygen step is very important but not mentioned in the GitHub web sites ...

7. Generating SSH keys(Github needs it):

In the terminal type

   >ssh-keygen -t rsa -C "xxxx@yzmail.com"

and just press enter for the next 3 statements.

Now execute the following commands :

      ravi@Hackintosh:~$ cd .ssh
      ravi@Hackintosh:~/.ssh$ gedit id_rsa.pub 

The file will be opened in gedit just COPY all the contents and close it and paste the contents in temporary document for later use.( For more info :http://help.github.com/linux-key-setup/)

AWK tutorials

http://bashshell.net/stream-filtering-utilities/exercise-1-learning-awk-basics/

http://bashshell.net/nagios-plugins/checking-processes-for-memory-use/

http://bashshell.net/utilities/exercise-2-learning-awk-with-operators/

http://bashshell.net/utilities/exercise-3using-awk-with-print-and-printf/

HowTo: Recovering Linux Grub Boot Loader Password

http://www.cyberciti.biz/tips/howto-recovering-grub-boot-loader-password.html

How to prevents users from entering single user mode or changing settings at boot time ?

When your system is rebooted, grub presents the boot option menu. From this menu one can easily login into a single user mode without the password which might result into compromise system security.

For example, anyone can access the data or change the settings. However you can setup a password for grub with password option. This option forces grub to ask for a password before making any changes or entering into single user mode. You need to type p followed by password.

#1: Create A Password For Grub

Type grub-md5-crypt command to create password in MD5 format:
# grub-md5-cryptOutput:

Password:
Retype password:
$1$NYoR71$Sgv6pxQ6LG4GXpfihIJyL0

Please note that you need to copy and paste the MD5 password ($1$NYoR71$Sgv6pxQ6LG4GXpfihIJyL0) to your configuration file. Use mouse to copy the same.

#2 Add MD5 Password To Grub Configuration File

Under Debian GNU/Linux the Grub configuration file is located at /boot/grub/menu.lst. (Red Hat / Fedora user use /boot/grub/grub.conf file)
# vi /boot/grub/menu.lst
Edit file and add a password line as follows:
password --md5 $1$NYoR71$Sgv6pxQ6LG4GXpfihIJyL0
Here is my sample config file:

default         0
timeout         5
password --md5 $1$NYoR71$Sgv6pxQ6LG4GXpfihIJyL0
title           Debian GNU/Linux, kernel 2.6.13.4-cust-en-smp
root           (hd0,0)
kernel        /boot/vmlinuz root=/dev/hda3 ro
savedefault
boot

Save and close the file.

http://www.cyberciti.biz/tips/how-do-i-secure-grub-boot-loader.html