shell

Instruction file imported from z-shell/.github (.github/instructions/shell.instructions.md). Copyright stays with the author.

Shell Dialect Dispatcher

Classify shell dialect from the actual shebang, invocation, repository contract, and behavior before applying language rules. Treat .sh only as a naming clue. When evidence conflicts, stop and resolve the dialect instead of importing a default.

Zsh

For native Zsh, read .github/instructions/zsh-scripting.instructions.md and lib/zsh-standard-policy.json. Apply its execution profile, compatibility, syntax, state, and tool boundaries. ShellCheck is not used for Zsh.

Bash

For Bash, use Bash semantics and declare the supported Bash floor. ShellCheck may run only with Bash selected explicitly as its dialect. Validate behavior under the actual Bash versions the repository supports.

POSIX sh

For POSIX sh, limit syntax and builtins to the repository's declared POSIX environment. ShellCheck may run only with sh selected explicitly as its dialect. Test against the implementations the repository supports.

Common rules

• Validate untrusted input before interpreting it.
• Avoid unreviewed eval and other code re-evaluation.
• Use reliable structured-data parsers instead of ad hoc text splitting.
• Handle critical command and pipeline statuses explicitly.
• Create temporary resources safely and guarantee cleanup.

No shebang, error-option bundle, array model, condition syntax, declaration builtin, or word-splitting rule is universal across shell dialects. Select each construct only after declaring the dialect and execution context.