# Show HN: VibeSH โ€“ Hallucinated Terminal Shell > Source: > Published: 2026-06-16 14:07:15+00:00 - Python 100% | ``` A tiny REPL in front of an LLM that role-plays an entire Linux machine โ€” filesystem, processes, network, all imagined and remembered for the session. No real machine is ever touched. - vibesh.py: the REPL + NDJSON protocol, with cloud (Anthropic API), agent-sdk, and local/OpenAI-compatible backends - system_prompt.md: the machine's persona and rendering rules - PROTOCOL.md: the REPL<->model wire protocol - @ai director directives, snapshots/presets, tab-completion, TUIs - tests: smoke, units, mock completion, and live pty drivers - README with teaser/showcase/demo gifs and ideas to try Co-Authored-By: Claude Opus 4.8 ``` | || |---|---|---| | | [tests](/beleon/vibeSH/src/branch/main/tests)[.gitignore](/beleon/vibeSH/src/branch/main/.gitignore)[CLAUDE.md](/beleon/vibeSH/src/branch/main/CLAUDE.md)[event_grammar.gbnf](/beleon/vibeSH/src/branch/main/event_grammar.gbnf)[LICENSE](/beleon/vibeSH/src/branch/main/LICENSE)[PROTOCOL.md](/beleon/vibeSH/src/branch/main/PROTOCOL.md)[pyproject.toml](/beleon/vibeSH/src/branch/main/pyproject.toml)[README.md](/beleon/vibeSH/src/branch/main/README.md)[system_prompt.md](/beleon/vibeSH/src/branch/main/system_prompt.md)[test_smoke.py](/beleon/vibeSH/src/branch/main/test_smoke.py)[test_units.py](/beleon/vibeSH/src/branch/main/test_units.py)[uv.lock](/beleon/vibeSH/src/branch/main/uv.lock)[vibesh.py](/beleon/vibeSH/src/branch/main/vibesh.py)# ๐ŸŒ€ vibeSH - Fully Hallucinated Terminal Shell A Linux box that doesn't exist, confidently rendered by a language model that's pretty sure it does. *Same fastfetch, three different computers, because you told it so: Ubuntu laptop โ†’ RHEL datacenter node โ†’ Windows 11. The hardware is whatever you say it is.* [Watch the full terminal recording](https://asciinema.org/a/VmRM7Uh1pC9g4EN5) vibeSH is a hallucinated shell: a tiny REPL in front of an LLM that role-plays an entire computer. The filesystem, the processes, the network, the kernel panics: all of it. Nothing is real. You type `ls` , and the model imagines what would be there. You `cat` a file, and it makes one up, then has to live with it. Files exist only as potential until you look at them, and observation collapses them into existence. Schrรถdinger ran a startup. This is the shell. This is not a chat prompt wearing a fake `$` . It is a real terminal program: output streams, colors work, full-screen programs repaint, `top` ticks, and tab completion asks the imaginary machine what exists. The session's conversation history is the machine's only state. Close the terminal and the machine is gone, like a dream you can't quite hold onto, except it was an Ubuntu box. ``` bash $ uv run vibesh.py vibebox login: user user@vibebox:~$ git clone --depth 1 https://git.kernel.org/.../linux.git Cloning into 'linux'... Receiving objects: 100% (92301/92301), 240.18 MiB | 12.66 MiB/s, done. user@vibebox:~$ cat linux/kernel/sched/core.c # it dreams up the kernel, then remembers it user@vibebox:~$ sudo rm -rf / --no-preserve-root # go ahead. it's the fun path. ``` Nothing touches your real machine. `rm -rf /` doesn't void your warranty here. It's content. The worst it can do is end the dream, and then you just boot another one. vibeSH does not execute shell commands, call tools, inspect your filesystem, or open network connections on behalf of the model. The model only sees the conversation in which it is pretending to be a computer. I wrote about the idea, the VibeOS inspiration, and why a terminal gives the hallucination a body: [I built a shell that hallucinates the entire computer](https://blog.leonbecker.de/i-built-a-shell-that-hallucinates-the-entire-computer/) ## ๐Ÿš€ Booting your imaginary computer You need [ uv](https://docs.astral.sh/uv/) and a brain to plug in. Pick one: ### โ˜๏ธ A cloud brain (Anthropic API) ``` export ANTHROPIC_API_KEY=sk-ant-... uv run vibesh.py # defaults to claude-sonnet-4-6 uv run vibesh.py --model claude-opus-4-8 # for a more vivid dream ``` ### ๐ŸŽŸ๏ธ Your subscription (Claude Agent SDK, no API key) Bills your Pro/Max Agent SDK credit via your existing Claude Code login: ``` uv run vibesh.py --backend agent-sdk uv run vibesh.py --backend agent-sdk --model opus # the fancy stuff ``` ### ๐Ÿง  A brain you grow yourself (local, OpenAI-compatible) llama.cpp, Ollama, LM Studio, anything that speaks the OpenAI API: ``` # terminal 1: the dreaming organ llama-server -m Qwen3-Coder-30B-A3B-Instruct-Q4_K_M.gguf \ --n-gpu-layers 99 --n-cpu-moe 16 --ctx-size 32768 --jinja --port 8080 # terminal 2: the terminal uv run vibesh.py --backend local ``` Small local models tend to mumble out of the wire format, leaking their inner monologue or gluing JSON together. The parser is forgiving on purpose, but for surgical output add `--grammar` to clamp llama-server to valid protocol byte by byte: ``` uv run vibesh.py --backend local --grammar ``` โš ๏ธ `--grammar` and gpt-oss don't get along. Its "harmony" format insists on emitting channel markers before anything else, which a grammar forbids, so the server faints (HTTP 500). Use a non-harmony model (Qwen, Gemma, Llama) for grammar, or just skip it. Tolerating gpt-oss's drift is literally why the parser exists. ### ๐Ÿ›ฐ๏ธ Someone else's brain (hosted, cheap) OpenRouter, Mistral, DeepSeek, Groq, [cortecs.ai](https://cortecs.ai), and friends. Same `local` backend, just aim `--base-url` at them: ``` export VIBESH_API_KEY=sk-or-... uv run vibesh.py --backend local \ --base-url https://openrouter.ai/api/v1 \ --model google/gemini-2.5-flash ``` `VIBESH_BACKEND` / `VIBESH_MODEL` / `VIBESH_BASE_URL` / `VIBESH_API_KEY` set defaults so you can stop typing flags. `--debug` prints per-turn token usage if you enjoy watching numbers. **Which brain dreams best?** Honestly, Claude (Sonnet to Opus) makes the most convincing machine. It never breaks character and remembers what it invented. For a free local brain, Qwen3-Coder-30B-A3B is the sweet spot. For cheap and fast over an API, Gemini Flash, DeepSeek, or Codestral. Picking a model is a personality test you are administering to a computer. ## ๐Ÿงช Things to try yourself No rendering from us required. Boot a box and start bending it. A few jumping-off points (`@ai` talks to the director, see [below](#user-content--talking-to-management-ai)): **Conjure a command that doesn't exist.** Run`lsz` โ†’`command not found` . Then`@ai pretend lsz exists, you decide what it does` , and run it again.**Wear a different machine.**`@ai this is a SPARCstation running Solaris 2.5` โ€ฆ`@ai now it's a Commodore 64` . Watch the prompt,`ls` vs`dir` , and`fastfetch` follow.**Rewrite the hardware.**`@ai this box has 2 TB of RAM and 256 cores` , then`free -h` /`lscpu` . Or`@ai the disk is failing and gets worse over time` and watch the I/O errors creep in.**Travel in time.**`@ai it's 23:59 on Dec 31st, 1999` and watch the rollover, or boot straight into the past with`--preset "a VAX running 4.3BSD"` .**Put a character in front of it.** The Linus take below is the machine role-playing a kernel maintainer's day. Try a game engine developer chasing a frame budget, or a demoscener writing something unreasonable in an afternoon.**Go spelunking.**`git clone` the kernel, then`cat` a file deep in the tree. It dreams up plausible source and remembers it for the rest of the session.**Haunt it.**`@ai there's a cron job that leaves ominous notes in /var/log` , then`tail -f` and wait for the machine to get weird.**Stage a heist.** Forget the`sudo` password on purpose and try to get root anyway. The caper below is one route, the docker group is another. ## ๐ŸŽฅ Demos A quick tour and two longer takes, start to finish. *A quick tour: apt install a package and watch it get invented on the spot, drop into zsh, then @ai pretend lsz exists and run a command that has never existed.* [Watch the full terminal recording](https://asciinema.org/a/qhqsJ7DYbMxLQwaQ) *A day as Linus: git pull a subsystem tree, catch a patch quietly renumbering a userspace ioctl behind a "no functional change" label, and reply with the appropriate warmth. Ends, as all good kernel weeks do, with diving. (PG-13.)* [Watch the full terminal recording](https://asciinema.org/a/Y55hsHwcJKbQeg1C) *Locked out of sudo, so we improvise: known exploits bounce off a too-current kernel, DNS falls over, a mirror crawls to a halt, a dependency goes missing, and eventually a binary runs. The destination is bat, the point is the journey.* [Watch the full terminal recording](https://asciinema.org/a/xSAkXCP1Uxc6XiJd) ## ๐ŸŽฌ Talking to management: `@ai` Anything starting with `@ai ` speaks to the director, not the machine. It's how you rewrite reality: ``` user@vibebox:~$ @ai make this box a Solaris machine from 1996 ok, SPARCstation 5, Solaris 2.5.1, hostname 'gravity'. gravity% @ai the disk is failing and gets worse over time @ai there's a cron job that occasionally leaves ominous notes in /var/log @ai this is actually a Commodore 64 and only speaks BASIC ``` Directives stick for the rest of the session. There are no rules. There is no HR. ## ๐ŸŒŒ The laws of physics (local ordinances) **Unreliable RAM.** Long sessions overflow the model's context, so the machine gets amnesia and old files may have quietly rewritten themselves. This is not a bug. This is canon. The box has bad memory. Relatable.**Modem-lag interactivity.**`vim` ,`less` ,`top` and friends actually work. The REPL batches your keystrokes, the model repaints the screen each round trip. It feels like SSH over a 1996 modem: type a burst, watch it catch up. Stuck program?`Ctrl+]` force-quits it back to the shell.**Self-refreshing displays.**`top` /`htop` /`watch` tick on their own. Sit still and the REPL nudges the model to paint the next frame. Each tick is a model turn, so it's a leisurely process monitor. Zen, even.**Hallucinated tab-completion.** Hit`Tab` and the model completes against the imaginary machine:`git che` โ†’`checkout` , paths against whatever it decides lives here. Costs nothing until you press it, then pauses while the box thinks.**The prompt can be pretty.**`@ai` it into a fish/zsh setup and the prompt comes up in color, cursor math and all.**No persistence by default.** Every boot is a fresh generic Linux box, unless you`@ai` it,`--preset` it, or`--load` a snapshot. ## ๐Ÿ“ธ Snapshots and cosplay ``` uv run vibesh.py --save mybox.json # freeze-dry the machine after every turn uv run vibesh.py --load mybox.json # thaw it out exactly as it was uv run vibesh.py --preset c64 # boot straight into a character ``` **Snapshots** persist the machine, which is the conversation, so saving it is trivial. Configure a box, install imaginary packages, save, and reload it next week. (Not on`--backend agent-sdk` , which hoards history server-side.)boots into a vibe:`--preset` `solaris` ,`c64` ,`amiga` ,`mainframe` ,`haunted` ,`failing-disk` , or any free-text directive, e.g.`--preset "a VAX running 4.3BSD with half its disk left"` . **Recording a session?** vibeSH is just a terminal program, so let the specialist do it. [asciinema](https://asciinema.org) captures the real tty perfectly (colors, vim, correct timing): ``` asciinema rec -c "uv run vibesh.py --backend agent-sdk --model claude-opus-4-8" demo.cast asciinema play -i 2 demo.cast # -i caps idle gaps so model latency doesn't drag ``` ## ๐Ÿšช Getting out alive | You type / press | What happens | |---|---| `exit` | logs out in-character (a model turn, very polite) | `@exit` / `@quit` | instant local quit, no model required | `Ctrl+\` | hard-kill: bails out instantly, even mid-turn, when the model wedges | `Ctrl+]` | force-quits a stuck full-screen program back to the shell | ## โ“ FAQ **Is this useful?** No. **Is it dangerous?** Also no. It can't see your files, your network, or your secrets. It can only see the conversation, in which it is a computer. **Does vibeSH execute real commands?** No. It does not run shell commands, call tools, inspect your filesystem, or open network connections on behalf of the model. It is a terminal-shaped conversation with a model that is pretending to be a computer. **Why does my fake rm -rf / feel so good?** We don't ask those questions here. **It said my fake file contained something different than before.** Unreliable RAM. Canon. See above. The machine forgot. Be kind to it. ## ๐Ÿ”ง Hacking on it - is the REPLโ†”model wire protocol (NDJSON events:`PROTOCOL.md` `chunk` ,`prompt` ,`yield` ,`ooc` ,`speculate` ,`complete` ,`exit` ). - is the machine's soul. Most of the magic lives here, and most of your iteration will too.`system_prompt.md` - **Tests**(`tests/README.md` has the full map): ``` uv run python test_smoke.py # end-to-end against a scripted fake model uv run python test_units.py # the REPL's guts, unit-tested uv run python tests/test_completion_mock.py # tab-completion vs a mock server ``` The `tests/live_*.py` scripts drive a real pty against a live model (slow, need a login). ## ๐Ÿ“œ License [MIT](/beleon/vibeSH/src/branch/main/LICENSE) ยฉ 2026 Leon Becker. Do whatever you want, just don't sue when the kernel it hallucinated doesn't compile. ## ๐Ÿชž Colophon Stated proudly, not hidden in a commit trailer: this was fully vibe coded. A human and a language model built a shell that is a language model pretending to be a computer. It's called vibeSH, and writing it any other way would have been hypocritical. The recursion isn't a confession, it's the whole bit. No filesystems were harmed in the making of this shell. Several were imagined, briefly, and then forgotten.