How can I prepend a string to the beginning of each line in a file?

How can I prepend a string to the beginning of each line in a file?

References

Reference NO 1

http://stackoverflow.com/questions/2099471/add-a-prefix-string-to-beginning-of-each-line

Reference NO 2

http://stackoverflow.com/questions/9588533/how-to-add-a-string-at-the-beginning-of-each-line-in-a-file

Reference NO 3

http://www.unix.com/unix-dummies-questions-answers/116741-adding-one-string-beginning-each-line-file.html

Reference NO 4

http://serverfault.com/questions/72744/command-to-prepend-string-to-each-line

Reference NO 5

http://www.linuxquestions.org/questions/programming-9/insert-string-with-sed-257625/

Reference NO 6

http://askubuntu.com/questions/11031/add-a-string-to-a-text-file-from-terminal

Reference NO 7

http://www.dostips.com/forum/viewtopic.php?f=3&t=3405

Reference NO 8

http://www.cyberciti.biz/faq/bash-prepend-text-lines-to-file/