Bash

Strict mode

set -euo pipefail
IFS=$'\n\t'

• -e is suppressed in conditional contexts (||, &&, if, !); explicit subshells (...) do inherit it — use || true to absorb expected failures.
• -u treats unset variables as errors; unset arrays trigger it: declare before use (arr=()) or guard with ${arr[@]+"${arr[@]}"} for optional arrays.
• IFS=$'\n\t' prevents accidental word-splitting on spaces in for loops and command substitution.

Quoting and tests

• Always "$var" — bare $var triggers word splitting and glob expansion.
• 'literal' for fixed strings with no expansion needed.
• Prefer [[ ]] over [ ]: supports =~ regex, no word splitting, lexical string comparison.
• $() over backticks: nestable, readable, no escaping required.