Shell Break long lines on |, &&, or || and indent the continuations. Don't add an extension to executable shell scripts. Don't put a line break before then or do, use if ...; then and while ...; do. Use for x; do, not for x in "$@"; do. Use snake_case for variable names and ALLCAPS for environment variables. Use single quotes for strings that don't contain escapes or variables. Use two-space indentation.