bash-syntax-in-sh
Bash-specific syntax in /bin/sh scripts breaks on dash/ash
Applies to: Shell
Why this matters
On many systems (Docker/Alpine, Debian, Ubuntu), /bin/sh is dash or ash, not bash. Bash-specific syntax like [[ ]], <<<, arrays, and pattern substitution will cause silent failures or cryptic syntax errors in these environments.
Catch it before it ships
pip install stablestack # or: npx stablestackstablestack # scans your project, QUAL018 includedstablestack explain QUAL018QUAL018 is part of the Pro rule set. See pricing — the free tier ships 24 checks with no signup.
False positive in your codebase? Suppress a single line with # noqa: QUAL018
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