Echo can interpret operand as an option and checking every variable to
be echoed is troublesome while with printf, if the format specifier is
present before the operand, printing as string can be enforced.
Make shell a little bit safer with:
- add-default-case
- check-extra-masked-returns
- check-set-e-suppressed
- quote-safe-variables
- check-unassigned-uppercase
Although there are some stylistic decisions for uniformity:
- avoid-nullary-conditions
- deprecated-which
- require-variable-braces
