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

# shell

> Contract, placement, related fields and source examples for this Nika YAML field.

[Language reference](/reference/language/overview) / `shell`

## Meaning and placement

### exec

One shell line, run via /bin/sh -c — the EXPLICIT dangerous door (pipes · redirects · globs). The blocklist applies here; interpolating untrusted values here is on the author. Exactly one of command|shell.

| Property        | Declaration                    |
| --------------- | ------------------------------ |
| Requirement     | Optional in this object        |
| Schema location | `/$defs/exec/properties/shell` |
| type            | "string"                       |
| minLength       | 1                              |

**In the same object:** [capture](/reference/language/words/capture) · [command](/reference/language/words/command) · [cwd](/reference/language/words/cwd) · [decode](/reference/language/words/decode) · [env](/reference/language/words/env) · [stdin](/reference/language/words/stdin)

[Schema source (use the pointer above)](https://github.com/supernovae-st/nika-spec/blob/c5ebbb7b862b68bc6cf7235efba61173b844afc6/schemas/workflow.schema.json)

## Examples

No matching source-template occurrence is recorded in this projection. [Write a workflow](/guides/templates) or consult the schema declaration above.

## Contract and implementation

This page projects the named specification revision. Check [released engine status](/reference/status) and [the validation workflow](/guides/agent-authoring) before running a file. An optional field is not evidence that every engine supports every value.

Canonical identity: `language:word:shell`. Spec revision: [`c5ebbb7b862b`](https://github.com/supernovae-st/nika-spec/tree/c5ebbb7b862b68bc6cf7235efba61173b844afc6).

[How documentation stays connected](/reference/knowledge-system).