Break, Continue, and Early Exit Patterns

Break, Continue, and Early Exit Patterns

Controlling loop flow and establishing defensive guard clauses prevents deeply nested indentation.

# Guard clause pattern: validate early, exit early
process_file() {
    local file="$1"
    [[ -f "$file" ]] || return 1
    [[ -r "$file" ]] || return 2

    # Actual work continues un-indented
    cat "$file"
}

# Multi-level break
for outer in {1..5}; do
    for inner in {a..e}; do
        if [[ $outer -eq 3 && $inner == "c" ]]; then
            break 2 # Exits BOTH inner and outer loops
        fi
    done
done