Bash Guidelines

Write Bash scripts that are idiomatic, robust, and readable. ShellCheck compliance is mandatory — run in CI.

Setup

Every script starts with:

#!/usr/bin/env bash
set -euo pipefail

• -e — exit immediately on error
• -u — treat unset variables as errors
• -o pipefail — propagate errors through pipes

Variables

• Quote all expansions: "$VAR", "${VAR}".
• Use readonly for constants: readonly MAX_RETRIES=3.
• Use local for all variables inside functions.

Functions

• Extract reusable logic into named functions.
• Define functions before they are called.
• Use explicit return <code>; never rely on the exit code of the last statement.

Error Handling

• Print errors to stderr: echo "Error: ..." >&2.
• Use trap for cleanup: trap cleanup EXIT.
• Check required commands exist: command -v docker >/dev/null || { echo "docker not found" >&2; exit 1; }.

Style

• Prefer [[ ]] over [ ] for conditionals.
• Prefer printf over echo for portability.
• Use $(command) for command substitution, not backticks.

Unix Philosophy

• Silent on success; errors to stderr.
• Exit 0 on success; non-zero on failure.
• Do one thing; compose with pipes.

Directives

• Every script: #!/usr/bin/env bash + set -euo pipefail
• Quote all expansions: "$VAR", "${VAR}"; use readonly for constants; local inside functions
• Errors to stderr: echo "Error: ..." >&2; trap cleanup EXIT for cleanup
• Prefer [[ ]] over [ ], printf over echo, $(command) over backticks
• Silent on success; non-zero exit on failure; ShellCheck compliance in CI