notebook/content/gawk.md

title	TARGET DECK	FILE TAGS	tags
GAWK	Obsidian::STEM	linux::cli gawk	linux cli gawk

Introduction

%%ANKI Basic How was the name awk derived? Back: By taking the first initials of the original three creators.

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%%ANKI Basic What does the term awk refer to? Back: Both the awk program and the awk language. Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. https://www.gnu.org/software/gawk/manual/gawk.pdf

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Dark corners are basically fractal - no matter how much you illuminate, there's always a smaller but darker one.

The above quote is attributed to Brian Kernighan (one of the authors of the C K&R book).

%%ANKI Cloze Dark corners are basically {1:fractal} - {1:no matter how much you illuminate, there's always a smaller but darker one.} - Brian Kernighan Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. https://www.gnu.org/software/gawk/manual/gawk.pdf

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Setup

Robbins¹ suggests executing command set +H on bash startup to disable C shell-style command history.

Usage

awk applies actions to lines matching specified patterns. In this way awk is said to be data-driven - we specify the lines awk should act on and awk is responsible for finding and acting on them. Instructions are provided via a program.

%%ANKI Basic What is the basic function of awk? Back: To apply actions to lines matching specified patterns. Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. https://www.gnu.org/software/gawk/manual/gawk.pdf

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An awk program consists of rules, each made up by a pattern and action. For example:

BEGIN { print "hello world" }
pattern { action }

%%ANKI Basic An awk program consists of a series of what? Back: Rules. Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. https://www.gnu.org/software/gawk/manual/gawk.pdf

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%%ANKI Basic A rule found in an awk program consists of what two parts? Back: A pattern and an action. Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. https://www.gnu.org/software/gawk/manual/gawk.pdf

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%%ANKI Basic A standalone awk program usually has what shebang? Back: #!/bin/awk -f Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. https://www.gnu.org/software/gawk/manual/gawk.pdf

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1. Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. https://www.gnu.org/software/gawk/manual/gawk.pdf ↩︎