Harsha S. Adiga gives us an overview of the most commonly used command-line text tools.
FTA, "Much of Linux system administration involves tediously combing through plain-text configuration files. Fortunately, Linux has a rich array of UNIX-derived data extraction utilities, including head, tail, grep, egrep, fgrep, cut, paste, join, awk, and more. This article uses real-world examples that show how these simple command-line programs can make you a better sysadmin. This article looks at each data extraction utility and its options, applies them to typical files that are used in day-to-day work, and looks at how and why each tool is useful for pulling data from these files.
The Linux operating system is loaded with files: configuration files, text files, documentation files, log files, user files, and the list goes on and on. Quite often, those files contain information you need to access in order to find important data. Although you can easily dump the contents of most files to the screen with standard utilities such as cat, more, and others, there are utilities better suited for filtering and parsing out only those values that are relevant to you.
As you read this article, you can open your shell and try the examples of each utility."
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