This weekend I was planning to write a follow-up to my Intro to grep tutorial, but I decided to put that off for a bit. One of my friends asked me about extracting a subset of information from each line of a text file. Basically, he wanted the URL’s of all the RSS feeds in his OPML file. Because grep returns whole lines, it isn’t equipped to the task. However, Linux comes with two popular stream editors: awk and sed. Today, I’m going to give you a proof-by-example of awk.
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SSH stands for Secure SHell. From the earliest days of networking, users were given accounts referred to as “shell accounts.” Basically, a user could connect to a remote system via a program called telnet, which I’ve detailed on this site before. You can think of an email account as a type of shell account. You have an account on a remote system, and you use a program (in this case it actually is telnet most of the time) to connect to that system to do work. A true shell account would give you the command line interface to the system you are connecting to, in effect putting you at the console of that system. The purpose of this tutorial, however, isn’t to detail the merits of using shell accounts (that would be a tutorial series in itself), but to explain SSH.
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