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Using terminal and dig to check your DNS records

Recently I had an error with a domain smtp server not recognising port 587.  To begin to test what was happening I wanted to get some key information about the server.  My tool of choice was the dig command.  Using the dig command:

regex expressions a working sheet

Regular expressions (regex) are extremely useful in extracting information from any text by searching for one or more matches of a specific search pattern.

yum command for clearing cache and make

Whilst updating nodejs and npm on a Centos 6 or 7 server running Apache, I hit a few walls and as a matter of process found some commands that are handy to run before doing a deep dive in Google.

 

Cleaning the cache

sudo yum clean all
rm -rf /var/cache/yum/*

To make the cache

sudo yum clean all; sudo yum makecache

If you want to run several commands use semi-colon as noted above.

 

vi(m) command mode

An outline of the vi(m) functions you can utilise whilst in command mode - yes they are case sensitive

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