Bash Koans

So I set up to learn Bash better. Normally I try to learn by doing koans, but I could not find any, so I decided to learn by building koans for Bash.

DISCLAIMER

I am no Bash expert. This is a project strictly for learning and fun. It's also not complete, I'm doing this when I have a moment.

If you are an expert, PLEASE contribute and make it even better!

How to

Just clone this repo and run:

./meditate

License

License is MIT. See LICENSE for details.

Lessons Learned from Bash Koans

6. Return Value Koan

• Understanding $?: Every command in Bash sets an exit status stored in $?.
  • 0 indicates success.
  • Non-zero indicates failure (commonly 1).
• Examples:
  • cd /nonexistent → exit status 1 (failure).
  • ls ~/ → exit status 0 (success).
• Key takeaway: Always check $? to determine if a command succeeded or failed, especially in scripts that depend on previous commands.

7. Variables Koan

• Local vs Global Variables:
  • local variables are only visible within the function they are defined in.
  • Variables defined without local are global and accessible anywhere.
• Variable Expansion:
  • Variables expand inside double quotes ("foo $var") and with ${var} syntax (this_is_${var}_yay).
• Unsetting Variables:
  • unset var removes a variable value so it no longer exists.
• Exporting Variables:
  • Only exported variables (export VAR=value) are visible to processes.
  • Local or nonexported variables remain invisible to processes.
• Key takeaway: Understanding scoping and exporting is crucial for writing reliable Bash scripts.