Regular expressions are extremely useful in extracting information from text such as code, log files, spreadsheets, or even documents. As an unix administrator we do regularly use the regex to perform various problem diagnosis , automation or remediation tasks. And it is almost impossible to imagine the life of unixadmin without RegEx usage. This quick virtual lab session will give you the basic usage knowledge of regular expressions with grep, which is a  essential skill required for unix system administrators.

Below is the Learning Map, that makes you comfortable with Grep  and RegEx ( i.e. Regular Expressions) within a day:

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Regular expressions are extremely useful in extracting information from text such as code, log files, spreadsheets, or even documents. As an unix administrator we do regularly use the regex to perform various problem diagnosis , automation or remediation tasks. And it is almost impossible to imagine the life of unixadmin without RegEx usage. This quick virtual lab session will give you the basic usage knowledge of regular expressions with grep, which is a  essential skill required for unix system administrators.

Below is the Learning Map, that makes you comfortable with Grep  and RegEx ( i.e. Regular Expressions) within a day:

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Cluster heartbeat connections are important components of VCS cluster, to allow cluster to work as expected for fail over and failback operations. In this post i will be showing to some basic verification that helps unix admins to confirm the health status of the cluster heartbeats.

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We are living in a trend of remote System Administration and in real-time we rarely touch and feel a server that we are managing for 24×7 ( 24 Hours a Day and 7 days a Week). Although we don’t really deal with our servers physically,  it is always better to know about the hardware that we have to support remotely. The Physical Server hardware awareness helps us for quick decision-making during the hardware troubleshooting. 

A decade ago, when I was learning my system administration course,  the most challenging task for me is imagine about how a real-time servers looks like and  how those servers are different from regular PCs. I couldn’t touch and feel a real server until I joined to my first job as UNIX admin and the server is Enterprise 450 ( a real elephant in shape and weight).

Today, Sysadmin learners are lucky enough to watch the real-time servers before they actually work on it, and the courtesy and credit goes to Oracle. Below are some of the important and powerful servers from oracle which are available in market for mission critical UNIX environment.

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Let us assume that our system administrator Jack is supporting for a server environment in which a small set of servers  are located in DMZ (Demilitarized zone ) network . In order to connect any DMZ server Jack has to ssh from his machine (windows PC/Unix workstation) to another server which acts as gateway between internal network and  DMZ network, and then he has to SSH to the DMZ server that he want to connect.

 Just to make his life easy to support these DMZ servers for his day-to-day system administration tasks, Jack wants to create a special encrypted tunnel from Jack’s host to the DMZ server.  He wants to achieve this goal by using the secured internal server (i.e. server1) as tunnel server between his PC/workstation and DMZ server.

 Jack’s Network Setup for SSH tunnel:

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Virtual LANs or VLANs are virtual separations within a switch that provide distinct logical LANs that each behave if there were configured on a separate physical switch. Some Important points about VLANS.

•  All the servers connected with in a VLAN will have same broadcasting domain, and can connect to each other directly
•  Servers belongs to different VLANs has to communicate with each other using external Routing device.  
•  To Expand the VLAN across multiple physical switches, physical switches needs to be interconnected using links called Trunks

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