How to get an Email alert from linux server

How to get an Email alert from linux server

References

Reference NO 1

http://www.howtogeek.com/51819/how-to-setup-email-alerts-on-linux-using-gmail/

Reference NO 2

http://stackoverflow.com/questions/15198552/how-to-get-an-email-alert-from-linux-server-when-any-file-updated

Reference NO 3

http://serverfault.com/questions/34141/send-email-alert-on-log-file-entry

Reference NO 4

http://www.mydigitallife.info/how-to-get-linux-server-sends-email-alert-on-root-login/

Reference NO 5

https://www.centos.org/modules/newbb/viewtopic.php?topic_id=41745&forum=59

Reference NO 6

http://www.cyberciti.biz/faq/apt-get-apticron-send-email-upgrades-available/

Reference NO 7

http://networklessons.com/linux/receive-e-mail-on-root-login/

Reference NO 8

http://www.techrepublic.com/forums/questions/linux-hardware-monitoring-via-email-alerts/