My book on "GNU grep and ripgrep" is free to download today and tomorrow [1][2]
Code snippets, example files and sample chapters are available on GitHub [3]
The book uses plenty of examples and regular expressions are also covered from scratch. The book is suitable for beginners as well as serves as a reference. Hope you find it useful, I would be grateful for your feedback and suggestions.
I used pandoc+xelatex [4] to generate the pdf.
[1] https://gumroad.com/l/gnugrep_ripgrep
[2] https://leanpub.com/gnugrep_ripgrep
[3] https://github.com/learnbyexample/learn_gnugrep_ripgrep
[4] https://learnbyexample.github.io/tutorial/ebook-generation/c...
BSD tail: https://searchcode.com/codesearch/view/457515/
GNU tail: https://github.com/coreutils/coreutils/blob/master/src/tail....
Usually the BSD one is short and sweet and the GNU one is a bit complex.
GNU utilities may be high performance but they tend to be hard to understand.