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Using UNIX is not always easy. The best way to get things done efficiently is though the command line and most users resent that.

There are a few essential concepts and utilities when working with a terminal that make life easy. The first concept is that for UNIX everything is a file. That means that everything is either accessible read-only, write-only, read-write or not at all. All the components attached to your computer are files too; the screen is a write-only file, the keyboard is a read-only device and the computer’s RAM is a read-write file. All files can therefore be opened for reading, writing or both. The next concept is one that is mainly a guideline that was used when UNIX was designed in the¬†eighties: You are better off with ten small programs that do one thing each but very reliably an efficiently than using one program that does ten things in a less reliable and efficient manner. From that principle emerged lodes of utilities like cat, grep, find, ps, sed, awk, more, tail and lots of others that are used by millions of users all over the world. The last one I would like to point out is used mainly by a smaller group that have to match patterns. These programs usually use regular expressions; a language designed to specify patterns of characters to be used either in a search and replace or a file search or even lots of other things. To learn a bit more about these regex as we call them, and learn a bit about “sed” the stream editor or rudimentary basics in “awk” Download the following PDF

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