Lab 03 -- Advanced Shell scripting

This page gives an overview of the lecture and the lab session on Aug 14, 2025.

Short lecture summary

Programming in shell, variables and special variables, performing evaluations, repetitions (for), conditionals (while and if). Logical expressions &&, || and !.
Use of & (background, foreground) and | pipes. /dev/stdin, /dev/stdout, /dev/stderr for input, ouput and error streams. File descriptor and uses of redirection >, >>, and <.
Coreutils - programs head, tail, shuf, less, sort, uniq, wc, tr, cut, awk, sed, grep, du, stat, find, wget, curl, date, bc.
Regular expressions
Getting help via info and man pages. Also searching manpages using apropos and using the help feature of bash.

The Linux Command Line by William Shotts (Online version)

Read chapters (PDF available here)
- Chapter 19 - Regular expressions
- Chapter 20 - Text processing
- Chapter 21 - Formatting output
- Chapter 30 - Troubleshooting
Dive Into Systems by Suzanne J. Matthews, Tia Newhall, Kevin C. Webb (Online version)

Read chapters
- Chapter 13. The Operating System
Useful commands from the GNU Coreutils and more summarised in 108 Youtube videos (each a few minutes long). If you would like a text summary, you can find it here.
Lectures 5, 6, 8, 9, 10, 11, 13, 14 and 15 of Unix Tools and Scripting course at Cornell.

Read and practise the exercises from Bash academy
You can also check pdf version of this document and also an older (but more complete) html version. It has lots of information on good practises and usual pitfalls to avoid in the context of writing shell scripts.
Learn and practise regular expressions. It is a powerful tool of great help. You can practise from this website.