1. Stop MySql server using following command.

$ sudo /etc/init.d/mysql stop

2. Copy the existing data directory (which is located in /var/lib/mysql) using following command.

$ sudo cp -R -p /var/lib/mysql /path/to/new/datadir

3. Edit the MySQL configuration file with your favorite text editor.

$ sudo vim /etc/mysql/my.cnf

4. Find the entry for datadir, change the path to the new data directory.
5. Some Linux distributions uses some security software called AppArmor that specifies the areas of your filesystem applications are allowed to access. Unless you modify the AppArmor profile for MySQL, you’ll never be able to restart MySQL with the new datadir location. So edit the file /etc/apparmor.d/usr.sbin.mysqld using your favorite editor.

$ sudo vim /etc/apparmor.d/usr.sbin.mysqld

6. Duplicate the lines beginning with /var/lib/mysql and replace duplicated strings with /new_datadir.

/var/lib/mysql/ r,
/var/lib/mysql/** rwk,
/var/log/mysql/ r,
/var/log/mysql/* rw,
#
/path/to/new/datadir r,
/path/to/new/datadir** rwk,
/path/to/new/datadir r,
/path/to/new/datadir* rw,

7. Restart the AppArmor profiles with the following command.

$ sudo /etc/init.d/apparmor restart

8. Restart the MySql server with the following command.

$ sudo /etc/init.d/mysql start

MySQL should now start without any errors and your data will be stored in the new location.

dmidecode  is a tool for dumping a computer’s DMI (some say SMBIOS) table contents in a human-readable format. This table contains a description of the system’s hardware components, as well as other useful pieces of information such as serial numbers and BIOS revision. Thanks to this table, you can  retrieve  this information without having to probe for the actual hardware.  While this is a good point in terms of report speed and safeness, this also makes the presented information possibly unreliable.

The DMI table doesn’t only describe what the system is currently made of, it also can report the possible evolutions (such as the fastest supported CPU or the maximal amount of memory supported).

SMBIOS  stands  for  System Management BIOS, while DMI stands for Desktop Management Interface. Both standards are tightly related and developed by the DMTF (Desktop Management Task Force).

As you run it, dmidecode will try to locate the DMI table. If it succeeds, it will then parse this table and display a list of  records  like  this one:

DMI TYPES
       The SMBIOS specification defines the following DMI types:

       Type   Information
       ----------------------------------------

          0   BIOS
          1   System
          2   Base Board
          3   Chassis
          4   Processor
          5   Memory Controller
          6   Memory Module
          7   Cache
          8   Port Connector
          9   System Slots
         10   On Board Devices
         11   OEM Strings
         12   System Configuration Options
         13   BIOS Language
         14   Group Associations
         15   System Event Log
         16   Physical Memory Array
         17   Memory Device
         18   32-bit Memory Error
         19   Memory Array Mapped Address
         20   Memory Device Mapped Address
         21   Built-in Pointing Device
         22   Portable Battery
         23   System Reset
         24   Hardware Security
         25   System Power Controls
         26   Voltage Probe
         27   Cooling Device
         28   Temperature Probe
         29   Electrical Current Probe
         30   Out-of-band Remote Access
         31   Boot Integrity Services
         32   System Boot
         33   64-bit Memory Error
         34   Management Device
         35   Management Device Component
         36   Management Device Threshold Data
         37   Memory Channel
         38   IPMI Device
         39   Power Supply

Additionally,  type 126 is used for disabled entries and type 127 is an end-of-table marker. Types 128 to 255 are for OEM-specific data.  dmidecode will display these entries by default, but it can only decode them when the vendors have contributed documentation or code for them.
Keywords can be used instead of type numbers with –type.  Each keyword is equivalent to a list of type numbers:

Keyword     Types
       ------------------------------
       bios        0, 13
       system      1, 12, 15, 23, 32
       baseboard   2, 10
       chassis     3
       processor   4
       memory      5, 6, 16, 17
       cache       7
       connector   8
       slot        9

To get physical memory details, use the following commainds.

$ sudo dmidecode -t 16
# dmidecode 2.9
SMBIOS 2.4 present.

Handle 0x000F, DMI type 16, 15 bytes
Physical Memory Array
	Location: System Board Or Motherboard
	Use: System Memory
	Error Correction Type: None
	Maximum Capacity: 4 GB
	Error Information Handle: Not Provided
	Number Of Devices: 2

$ sudo dmidecode -t 17
# dmidecode 2.9
SMBIOS 2.4 present.

Handle 0x0010, DMI type 17, 27 bytes
Memory Device
	Array Handle: 0x000F
	Error Information Handle: No Error
	Total Width: 64 bits
	Data Width: 64 bits
	Size: 1024 MB
	Form Factor: SODIMM
	Set: 1
	Locator: M1
	Bank Locator: Bank 0
	Type: DDR2
	Type Detail: Synchronous
	Speed: 667 MHz (1.5 ns)
	Manufacturer: Mfg 0
	Serial Number: 1234-B0
	Asset Tag: Not Specified
	Part Number: SODIMM000

Handle 0x0011, DMI type 17, 27 bytes
Memory Device
	Array Handle: 0x000F
	Error Information Handle: No Error
	Total Width: 64 bits
	Data Width: 64 bits
	Size: 2048 MB
	Form Factor: SODIMM
	Set: 1
	Locator: M2
	Bank Locator: Bank 1
	Type: DDR2
	Type Detail: Synchronous
	Speed: 667 MHz (1.5 ns)
	Manufacturer: Mfg 1
	Serial Number: 1234-B1
	Asset Tag: Not Specified
	Part Number: SODIMM001

“After The Software Wars”, is a new book in which former Microsoft employee Keith Curtis explores the worlds of proprietary and free software. Quoting from the article:

While I came to not be all that thrilled with Fedora itself, I was floored merely by the installation process. It contained a graphical installer that ran all the way to completion, it resized my NTFS partition — which I considered a minor miracle, setup dual boot, and actually did boot, and let me surf the Web. I didn’t have a clue what to do next, but the mere fact that this all worked told me more about the potential of Linux than anything I had read so far. You cannot, by accident, build an airplane that actually flies.

Read More : How A Microsoft Veteran Learned To Love Linux And Why It Matters

1. Install the package “bash-completion”

$ sudo apt-get install bash-completion

2. Add the following lines to the file ~/.bashrc or /etc/bash.bashrc

if [ -f /etc/bash_completion ]; then
    . /etc/bash_completion
fi

EUCALYPTUS — Elastic Utility Computing Architecture for Linking Your Programs To Useful Systems — is an open-source software infrastructure for implementing Elastic/Utility/Cloud computing using computing clusters and/or workstation farms. The current interface to EUCALYPTUS is interface-compatible with Amazon.com’s EC2 (arguably the most commercially successful Cloud computing service), but the infrastructure is designed to be modified and extended so that multiple client-side interfaces can be supported. In addition, EUCALYPTUS is implemented using commonly-available Linux tools and basic web service technology making it easy to install and maintain. For more information click here.

Get the User Guide from this link http://open.eucalyptus.com/wiki/EucalyptusUserGuide_v1.4

Date command to get the current date.

$ date=$(date +%Y-%m-%d)
$ echo $date

Date command to get yesterday’s date.

$ date=$(date --date=yesterday +%Y-%m-%d)
$ echo $date

Date command to get tomorrow’s date.

$ date=$(date --date=tomorrow +%Y-%m-%d)
$ echo $date

“This a true story of mine. I brought a Lenovo 3000N200 series laptop one year back, exactly 21’st Feb 2008 from Dubai Shopping festival for Rs 35, 000. I was very satisfied with their product initially, as it is cost effective with good performance. But after 3 months of working my laptop charger burnt out. I called up the customer care (18004252666) asking for the replacement and they said because it is burnt, they can’t replace it. For me, living without laptop and internet is worst thing in my life”

Read the complete story from the authors blog

eAccelerator is a free open-source PHP accelerator, optimizer, and dynamic content cache. It increases the performance of PHP scripts by caching them in their compiled state, so that the overhead of compiling is almost completely eliminated. It also optimizes scripts to speed up their execution. eAccelerator typically reduces server load and increases the speed of your PHP code by 1-10 times.

eAccelerator stores compiled PHP scripts in shared memory and executes code directly from it. It creates locks only for a short time, while searching for a compiled PHP script in the cache, so one script can be executed simultaneously by several engines. Files that can’t fit in shared memory are cached on disk only.

Installing From Source

unpack it by ::

$ sudo tar -xjvf eaccelerator-0.9.5.3.tar.bz2
$ cd eaccelerator-0.9.5.3/

Linux User Read README file

Windows User Read README.win32

Compile and install it with ::

./configure
make
sudo make install
make test

Add the below line to php.ini file

extension=eaccelerator.so

Check phpinfo()  and conform the module eAccelerator is loaded

$ vim swap-usage.sh

#!/bin/sh
free -m | grep Swap | while read output;
do
  swap=$(echo $output | awk '{print $2}' )
  used=$(echo $output | awk '{ print $3 }' )
  freed=$(echo $output | awk '{ print $4 }' )
  echo "Swap : $swap"
  echo "Used : $used"
  echo "Free : $freed"
  usep=`expr $used \* 100 / $swap`
  echo $usep
  if [ $usep -ge 70 ]; then
    echo "Swap Usage Alert Total Swap: \"$swap\" Used: \"$used ($usep%)\" Free:
\"$freed\" on $(hostname) as on $(date)" |
     mail -s "Alert: Swap Usage space $usep%" mail1@example.com,mail2@example.com
  fi
done

This script will send mails to the specified mails, if the system started to use more than 70% of  swap area. For continuously check the swap usage we need to set a cronjob for executing this script. So that the system should monit the swap usage by executing this script.

Edit the corntab file.

$ sudo crontab -e

Set the cronjob to to execute the script in every 15 Mints.

*/15 * * * * ~/scripts/swap-usage.sh

Restart the Cron

$ sudo /etc/init.d/cron restart

1. Create a Firewall script

 vim /etc/set_iptables.bash

echo 1 > /proc/sys/net/ipv4/ip_forward

iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
iptables -t nat -A PREROUTING -p tcp -i eth0 -d 192.168.0.10 --dport 555 -j DNAT --to 192.168.0.12:22
iptables -A FORWARD -p tcp -i eth0 -d 192.168.0.12 --dport 22 -j ACCEPT

2. Change the file permission mod

sudo chmod o+x /etc/set_iptables.bash

3. Create a start.stop script

vim /etc/init.d/iptables

#!/bin/bash

RETVAL=0

# To start the firewall
start() {
  echo -n "Iptables rules creation: "
  /etc/set_iptables.bash
  RETVAL=0
}

# To stop the firewall
stop() {
  echo -n "Removing all iptables rules: "
  /sbin/iptables -F
  RETVAL=0
}

case $1 in
  start)
    start
    ;;
  stop)
    stop
    ;;
  restart)
    stop
    start
    ;;
  status)
    /sbin/iptables -L
    /sbin/iptables -t nat -L
    RETVAL=0
    ;;
  *)
    echo "Usage: iptables {start|stop|restart|status}"
    RETVAL=1
esac
exit

4. Change the file permission mod

sudo chmod o+x /etc/init.d/iptables

5. The final step is to make your script running on each boot of your computer:

sudo update-rc.d iptables defaults

Now you can use these commands to start/stop/restart/status your iptables.

sudo /etc/init.d/iptables start
sudo /etc/init.d/iptables stop
sudo /etc/init.d/iptables restart
sudo /etc/init.d/iptables status