shell-dialectslisted

# Shell Dialects The differences between bash, fish, and zsh that break ported scripts. `portability` asks which distro breaks. This skill answers the other question: which parser to run and which semantics apply. Shell is two subjects, never one. **Script shell** is what `*.sh` files and `writeShellApplication` derivations produce, bash in practice, running unattended, owned by shellcheck. **Interactive shell** is whatever login shell the configuration declares, plus its config tree, where real logic often lives: status gates, process substitution, secret loading. shellcheck sees none of it. - **Parsers.** shellcheck cannot parse fish. On valid fish it exits 1 and reports `SC1073 Couldn't parse this function`, so its findings on fish are false errors on correct code. Gate fish with `fish -n` (exit 0 clean, 127 on a syntax error) and zsh with `zsh -n` (exit 1 on a syntax error). Measured 2026-07-24 on one Linux workstation. Unverified elsewhere. - **Pipeline status indexing.** bash `$PIPESTATUS` is zero-indexed: the first command is `[0]`. fish `$pipestatus` is one-indexed: the first command is `[1]`. zsh carries both, which is worse than carrying either. A script ported between them reads a real exit status from the wrong command and reports success. Measured 2026-07-24, same caveat. This entry leads because the failure is silent and costly. - **Process substitution.** `<(...)` in bash and zsh. It does not exist in fish, which needs `psub`: `-F` is