Greg Boyd's Notes
https://fog.ccsf.edu/~gboyd/cs160b/online/
Sed Tutorial
http://www.grymoire.com/Unix/Sed.html
Awk Tutorials
www.cs.unibo.it/~renzo/doc/awk/nawkA4.pdf
https://www.tutorialspoint.com/awk/index.htm
Shell Tutorials
https://www.tutorialspoint.com/unix/shell_scripting.htm