seanpm2001 / learn-awk

A repository for showcasing my knowledge of the Awk programming language, and continuing to learn the language.

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Learning AWK (programming language)

I know very little about the AWK programming language. This document will go over all of my knowledge of the AWK programming language.

Hello World in AWK

This is how you make a Hello World program in AWK:

BEGIN {
        print "Hello, world!"
        exit
}

Comments in AWK

Comments in AWK are the same as in Shell.

Single line comments

Single line comments in AWK are written like so:

# This is a single line comment

Multi-line comments

I don't know if AWK supports multi-line comments.

Break keyword in AWK

break

To this day, I am still not entirely sure what the break keyword does, but most languages support it.

/!\ This example has not been tested yet, and may not work

REGEX patterns in AWK

AWK supports REGEX (Regular Expression) patterns. They can be implemented like so:

/regex_pattern/ {
    # Actions to perform in the event the record (line) matches the above regex_pattern
    print 3+2
    print foobar(3)
    print foobar(variable)
    print sin(3-2)
}

The output can then be sent to a file directly

/regex_pattern/ {
    # Actions to perform in the event the record (line) matches the above regex_pattern
    print "expression" > "file name"
}

or through a pipe |

/regex_pattern/ {
    # Actions to perform in the event the record (line) matches the above regex_pattern
    print "expression" | "command"
}

These examples were taken directly from Wikipedia, and modified to fit how I interpret it.

/!\ This example has not been tested yet, and may not work

Other knowledge of the AWK programming language

1. AWK is a language by Alfred Aho, Peter Weinberger, and Brian Kernighan, of which the language is named after the first letter of their last names (AWK)

2. AWK is not a semicolon and curly bracket language, but it is a curly bracket language

3. AWK uses the *.awk file extension by default

4. AWK is a functional programming language

5. AWK is one of the default scripting languages in most UNIX/POSIX operating systems, such as Linux and BSD

6. AWK is one of the top 50 programming languages (as of 2022, July 31st, ranking #41)

7. AWK was first created in the year 1977

8. No other knowledge of the AWK programming language

Additional comments

1. I have not yet memorized the names of the developers

2. No other additional comments available

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File info

File type: Markdown document (*.md *.mkd *.mdown *.markdown)

File version: 1 (2022, Monday, August 1st at 5:08 pm PST)

Line count (including blank lines and compiler line): 158

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File history

Click/tap here to expand/collapse the history for this file

Version 1 (2022, Monday, August 1st at 5:08 pm PST)

Changes:

• Started the file

• Added the title section

• Added the Hello World in AWK section

• Added the Comments in AWK section

• Added the Single line comments subsection

• Added the Multi-line comments subsection

• Added the break keyword in AWK section

• Added the REGEX patterns in AWK section

• Added the other knowledge of the AWK programming language section

• Added the Additional comments section

• Added the file info section

• Added the file history section

• No other changes in version 1

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