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

# smolvm sandbox file

> Use smolvm sandbox file to upload files into a sandbox or download files back to your host over SSH or the SmolVM guest-agent channel.

`smolvm sandbox file` copies individual files between your host and a sandbox. Use it when you need to send a prompt, collect an artifact, or avoid sharing a whole folder.

## Synopsis

```bash theme={null}
smolvm sandbox file upload <sandbox> <local-path> <guest-path> [OPTIONS]
smolvm sandbox file download <sandbox> <guest-path> <local-path> [OPTIONS]
```

## Shared options

<ParamField path="--no-create-dirs" type="flag">
  Require parent directories to already exist instead of creating them.
</ParamField>

<ParamField path="--ssh-key" type="string">
  Path to an SSH private key when the command uses SSH.
</ParamField>

<ParamField path="--ssh-user" type="string" default="root">
  SSH user when the command uses SSH.
</ParamField>

<ParamField path="--comm-channel" type="string">
  Host-to-guest control channel. Use `ssh`, `vsock`, or omit it for auto-selection.
</ParamField>

<ParamField path="--json" type="flag">
  Print a JSON envelope instead of formatted text.
</ParamField>

## Upload a file

```bash theme={null}
smolvm sandbox file upload my-sandbox ./prompt.txt /workspace/prompt.txt
```

Force the guest-agent channel on a recent Linux sandbox:

```bash theme={null}
smolvm sandbox file upload my-sandbox ./report.csv /workspace/report.csv --comm-channel vsock
```

## Download a file

```bash theme={null}
smolvm sandbox file download my-sandbox /workspace/result.json ./result.json
```

## Use JSON output

```bash theme={null}
smolvm sandbox file upload my-sandbox ./input.txt /tmp/input.txt --json
```

```json theme={null}
{
  "ok": true,
  "command": "sandbox.file.upload",
  "exit_code": 0,
  "data": {
    "vm_id": "my-sandbox",
    "local_path": "input.txt",
    "guest_path": "/tmp/input.txt"
  },
  "error": null
}
```

## Related commands

* [Host mounts](/smolvm/features/host-mounts) - Share a whole folder
* [`smolvm sandbox env`](/smolvm/cli/env) - Set config values
* [Control channel](/smolvm/concepts/control-channel) - Learn how file transfer chooses SSH or vsock