Bash syntax used under a POSIX sh shell

What this failure means

A CI workflow or script selects sh but uses Bash-only syntax such as [[ ... ]], source, heredoc strings, functions, or set -o pipefail.

Diagnosis

The command is likely to run under POSIX sh while using syntax that requires Bash. This causes CI-only failures on runners where /bin/sh is not Bash.

Fix steps

1. Change the workflow step to shell: bash or update the script shebang to Bash.
2. If Bash is not required, rewrite the command using POSIX-compatible syntax.
3. Keep the selected shell and script syntax aligned in CI and local runs.

Validation

• Run faultline inspect . from the repository root and confirm this source finding is absent or intentionally mitigated.
• Run the script with the configured shell and confirm it exits successfully.

Why it matters

Shell dialect mismatches are portable until they are not: they often pass on one machine and fail on CI images where /bin/sh points to dash or another minimal shell.

Try it locally

make test
rg -n 'shell: sh|#!/bin/sh' .github/workflows scripts
make test
sh -n scripts/*.sh

How Faultline detects it

Use faultline explain shell-dialect-mismatch to see the full playbook.

faultline analyze build.log
faultline explain shell-dialect-mismatch

Generated from playbooks/bundled/source/shell-dialect-mismatch.yaml. Do not edit directly.