How to write terminal and shell commands with AI

By the end of this guide you will be able to describe a task in plain English, get a shell command from an AI tool, understand what it does, and run it safely. You will also know how to hand the AI an error message and get a fix. The tools that do this either sit inside your terminal session or run as a separate agent in the command line.

If you want to use an AI terminal command generator, the main choice is how much control the AI gets: it can suggest a command for you to copy, suggest and run it after you approve, or work as an agent that runs a sequence of commands. This guide covers all three, with six tools from our Coding category.

Key takeaways

• Describe the goal, the operating system and the folder you are in, ask for one command, and ask for an explanation before you run it.
• The main decision is how much the AI may do on its own: suggest only, run after your approval, or run as an agent with a goal.
• Several tools are free to install but need your own model key, so the model provider bills the usage. Check this before you start.
• Never run a command you cannot explain, especially one that deletes, moves or overwrites files or uses elevated privileges.

What you need before you start

• A terminal. Terminal on macOS or Linux, or a Linux shell on Windows. Some tools support only macOS and Linux.
• A model key or account. Most tools below use your own API key or a sign-in with an AI provider.
• A safe place to practise. A scratch folder with copies of any files you will touch.
• Time. Setup takes under an hour.
• Difficulty. Easy for suggest-only use, moderate for agents that run commands.
• A backup habit. Back up anything you cannot replace before running a command that changes it.

Which kind of AI tool fits this job

Choose by how much you want the AI to run for you.

AI inside your shell session. Butterfish wraps your bash or zsh session: any line that starts with a capital letter goes to a language model, and normal commands run as usual. Because it sees recent shell history and output, you can ask why the last command failed. It suggests commands as you type and has an agent-like Goal Mode. It runs on macOS and Linux and needs an OpenAI API key or a compatible server.

An assistant that watches your tmux panes. TmuxAI reads what is visible in every pane of your tmux window, answers in a chat pane, checks suggested commands against whitelist and blacklist patterns, and runs them in a separate pane only after you approve, edit or reject them. It suits people who already use tmux and SSH.

Terminal coding agents. Gemini CLI is Google's open-source terminal agent that can explain code, edit files and run shell commands. Grok Build is a terminal coding agent started with the grok command. fx is a small open-source agent for the terminal that you can call from shell scripts. Cline works in the editor and the terminal, and its overview says every action needs your approval.

Step 1: Write down what you want and where you are

A good request names the goal, the system and the starting point.

1. State the outcome in one sentence, such as "list the ten largest files in this folder".
2. Give your operating system and shell, for example macOS with zsh.
3. Say which folder you are in and whether the command should change anything.
4. Mention the tools you have installed if it matters.

Check it worked by reading the request and seeing that someone else could answer it without guessing.

Step 2: Choose a tool and set it up

You end this step with an AI that can see your terminal or accept requests from it.

1. Decide how much control to give: suggest only, approve each command, or goal-driven agent.
2. Check the platform. Butterfish and TmuxAI list macOS and Linux, and Grok Build lists macOS, Linux and Windows.
3. Check how the model is paid for. Butterfish needs an OpenAI API key or a compatible server, and fx bills model usage to the provider you choose.
4. Install the tool following its own instructions, then sign in or add your key.

Check it worked by sending a harmless request such as "print the current folder" and seeing a sensible command.

Step 3: Ask for a command and an explanation

Always ask the AI to say what the command does before you run it.

1. Send your request from Step 1.
2. Ask for one command and a line-by-line explanation of each part and each flag.
3. Ask whether it changes, deletes or overwrites anything.
4. Ask for a safer alternative if it does, such as a preview or dry-run option.

Check it worked by being able to explain the command to someone else in your own words.

Step 4: Preview before running

A preview turns a risky command into a safe one.

1. Run a read-only version first, such as listing the files a command would affect.
2. Use a dry-run flag if the command supports one.
3. Test in your scratch folder with copies of the files.
4. Be especially careful with commands that use elevated privileges or wildcards.

TmuxAI adds a built-in check here, asking you to approve, edit or reject each suggested command, while Butterfish lists an unsafe Goal Mode that runs commands without asking and can be dangerous. Check it worked by seeing exactly which files or items the command will touch.

Step 5: Run it and read the output

Run the command, then confirm the result matches your goal.

1. Run the command in the terminal, or approve it in the tool.
2. Read the output, including any warnings.
3. Verify the result directly, for example by listing the folder again.
4. Keep the command in a notes file if you may want it again.

Check it worked by comparing the result with the outcome you wrote in Step 1.

Step 6: Feed errors back to the AI

Errors are information, and the AI can use them.

1. In Butterfish, ask a capital-letter question about the last command, since the model sees recent history and output. In TmuxAI, ask in the chat pane, since it reads what is in your panes.
2. In other tools, paste the full error message and the command that caused it.
3. Ask what went wrong and for a corrected command with an explanation.
4. Repeat Step 4 before you run the new command.

Check it worked by getting through the command with no error and the right result.

Step 7: Save what works as a script or alias

Turn one-off commands into reusable tools.

1. Ask the AI to turn the command into a short shell script with comments.
2. Add safety checks, such as confirming a folder exists before using it.
3. Test the script on the scratch copy again.
4. Store it somewhere you will find it, with a note on what it does.

Agents such as fx can also be called from shell scripts, and Gemini CLI lists a headless mode for scripting. Check it worked by running the script from a different folder and seeing the same result.

Tools for this job compared

Tool	Good fit for	Pricing	Stated limits
Butterfish	AI prompts and autosuggest inside bash or zsh on macOS and Linux	Open source	Needs an OpenAI API key or compatible server, billed by that provider; Goal Mode described as hit or miss
TmuxAI	tmux users who want approved commands run in a separate pane	Open source	Needs tmux and macOS or Linux; one instance per tmux window; needs a model API key or local model
Gemini CLI	Terminal agent with file edits and shell commands, on macOS, Linux and Windows	Open source	Unpaid Gemini API key allows 250 requests a day on Flash models only; Antigravity CLI replaced it for unpaid-tier users
Cline	Agent in the editor and terminal with approval for every action	Open source, paid from $9.99/mo (checked 24 Oct 2026)	Model inference billed separately unless you use a free model option; JetBrains support needs Enterprise
fx	A tiny terminal agent you can call from scripts	Open source	Command line only; model usage billed by your provider; installer supports macOS and Linux
Grok Build	Terminal coding agent for macOS, Linux and Windows	Open source	External contributions not accepted; Windows source builds are best-effort; building from source needs Rust and DotSlash

Prices and plan limits change, so confirm the current terms on each vendor's site before you subscribe.

Common mistakes to avoid

• Running a command you do not understand. A plausible-looking command can delete files or change permissions. Fix it by asking for an explanation of every flag and previewing before you run.
• Letting an agent run unattended on real data. Goal-driven modes can chain commands that you never reviewed. Fix it by keeping approval on, working in a scratch folder, and avoiding any mode that runs commands without asking.
• Forgetting the system. Commands differ between macOS, Linux and Windows shells. Fix it by stating your system and shell in the request, and by checking the tool supports your platform.
• Pasting secrets into the prompt. Terminal output can contain keys, passwords or private paths, and tools send that context to a model. Fix it by removing sensitive values before you share output and by checking the provider's data terms.
• Skipping the cost check. Several tools are free but bill usage through your model provider. Fix it by reading how the quota or key is billed before you leave an agent running.

How we put this together

This is an evidence-based guide built from each tool's listing in our directory, which is compiled from the vendor's own site and pricing page. It is not a review based on using the tools. We don't rank tools, and nobody paid to be included. Some outbound links may be affiliate links; see our disclosure.

Frequently asked questions

Is there a free way to write terminal commands with AI?

Yes. Butterfish, TmuxAI, fx and Grok Build are open source, and Cline's open-source extension is free for individual developers. Gemini CLI lists free tiers, though its site says Antigravity CLI replaced it for unpaid-tier and Google One users in June 2026. Most still need a model key or account, so your model provider may charge for usage.

Can AI write shell commands accurately?

Often, but not always. Commands can be subtly wrong or too broad. Ask for an explanation, preview the effect and test on copies. Butterfish's author describes its Goal Mode as hit or miss, which is a fair warning for any agent.

Is it safe to let AI run commands for me?

Only with limits. Prefer tools that ask for approval, such as TmuxAI and Cline, work in a scratch folder, and keep backups. Avoid running anything with elevated privileges unless you fully understand it.

Which tool works on Windows?

Grok Build lists Windows, as do Gemini CLI and Cline's desktop and editor options. Butterfish, TmuxAI and fx list macOS and Linux only. Check each tool's current instructions.

Can I keep my terminal data private?

Tools that call a hosted model send your prompts and any context they read to that provider. TmuxAI and fx can use a local model, and fx can use any server that speaks the OpenAI Chat Completions API. Read your provider's data terms before sharing sensitive output.

Compare more options in our Coding category.