> ## Documentation Index
> Fetch the complete documentation index at: https://docs.yambr.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Code execution

> bash_tool runs anything in the sandbox — Python, Node, Java, Bun, ffmpeg, ImageMagick, git.

The `bash_tool` primitive runs arbitrary shell commands inside the chat's sandbox. Combined with the pre-installed stack, the model can do anything a developer can do.

## Languages

| Runtime | Version                                                     |
| ------- | ----------------------------------------------------------- |
| Python  | 3.12.3 (107 packages, incl. pandas/numpy/opencv/playwright) |
| Node.js | 22 (21 packages, incl. TypeScript/pdf-lib/mermaid-cli)      |
| Bun     | latest                                                      |
| Java    | OpenJDK 21                                                  |

## Behavior

* **Streaming output.** The tool streams stdout/stderr back to the model with 15-second heartbeats — no silent hangs.
* **Truncation-aware.** Output caps at 30K chars (first 15K + last 15K), so a runaway grep doesn't blow the context window.
* **Semantic exit codes.** `grep` returning `1` is treated as "no match," not an error.
* **Timeout.** Commands die after `COMMAND_TIMEOUT` seconds (default `120`). Override per call.

## Typical patterns

**Data wrangling**

```python theme={null}
python3 -c "
import pandas as pd
df = pd.read_csv('/mnt/user-data/uploads/sales.csv')
print(df.groupby('region')['revenue'].sum())
"
```

**Media**

```bash theme={null}
ffmpeg -i /mnt/user-data/uploads/clip.mov -vf scale=720:-1 /mnt/user-data/outputs/clip.mp4
```

**Git**

```bash theme={null}
git clone https://github.com/org/repo /tmp/repo && cd /tmp/repo && npm test
```

**Server**

```bash theme={null}
cd /home/assistant && python3 -m http.server 3000
```

The sandbox has its own network namespace — long-running servers stay up until the container is GC'd.

## When to prefer a skill

If a task fits a skill (docx, xlsx, pptx, pdf, playwright-cli, …), the skill has curated scripts that are faster, safer, and produce more polished output than hand-rolled bash. The model picks automatically based on the `<available_skills>` block in its system prompt.

## Related

* [Skills reference](/skills/reference)
* [Sub-agents](/features/sub-agents) — for multi-step, autonomous tasks