graverende:
* what I said about interpolation
* var=`:` true ikkeno galt i det
how to:
* Gotcha: Command substitution trim "$()".
* Use loops FTW
* Absorb into how to use errexit
* Absorb into conditions
Antipatterns:
* test -z or test -n
* xyes
* shelling out to find
* cp file dir
minor importance bugs:
* parser: $( in [[
* nesting $(())
* nesting braces in default value: "${bla-:"bla{}ukebla}"