UNION - GROUP BY

SELECT * FROM (
SELECT 1 AS ticked, col1, col2 FROM table1 INNER JOIN table2 USING (col3))
UNION
SELECT 0 AS ticked, col1, col2 FROM table1)
)AS combined_table /*derived tables need a unique name*/
GROUP BY col1 /*group by the unique col1 to stop duplicates*/
ORDER BY ticked DESC

taken from,
http://dev.mysql.com/doc/refman/5.0/en/union.html

Add lost public key of a repository

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 5A9A06AEF9CB8DB0

The hexa decimal value at the last can found with error message.

Perl Basics - Operators

Perl Basics: "numRows"

Color Bash Prompt - ArchWiki

Color Bash Prompt - ArchWiki:

"txtblk='\e[0;30m' # Black - Regular
txtred='\e[0;31m' # Red
txtgrn='\e[0;32m' # Green
txtylw='\e[0;33m' # Yellow
txtblu='\e[0;34m' # Blue
txtpur='\e[0;35m' # Purple
txtcyn='\e[0;36m' # Cyan
txtwht='\e[0;37m' # White
bldblk='\e[1;30m' # Black - Bold
bldred='\e[1;31m' # Red
bldgrn='\e[1;32m' # Green
bldylw='\e[1;33m' # Yellow
bldblu='\e[1;34m' # Blue
bldpur='\e[1;35m' # Purple
bldcyn='\e[1;36m' # Cyan
bldwht='\e[1;37m' # White
unkblk='\e[4;30m' # Black - Underline
undred='\e[4;31m' # Red
undgrn='\e[4;32m' # Green
undylw='\e[4;33m' # Yellow
undblu='\e[4;34m' # Blue
undpur='\e[4;35m' # Purple
undcyn='\e[4;36m' # Cyan
undwht='\e[4;37m' # White
bakblk='\e[40m' # Black - Background
bakred='\e[41m' # Red
badgrn='\e[42m' # Green
bakylw='\e[43m' # Yellow
bakblu='\e[44m' # Blue
bakpur='\e[45m' # Purple
bakcyn='\e[46m' # Cyan
bakwht='\e[47m' # White
txtrst='\e[0m' # Text Reset"

Changing font and color in log file of Script - The UNIX and Linux Forums

Changing font and color in log file of Script - The UNIX and Linux Forums

How To Search Shell Command History

#history | grep 'search key'

Linux Screen Tutorial

List of command to manage screen

• Create screen on terminal
• #screen 
• Terminate screen
• #exit
• View existing screen list
• # screen -ls