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

# Shell

> Semantic diffing for shell scripts

## Shell extractor

The Shell extractor (tree-sitter-bash) maps CST nodes to canonical concepts for `sh`, `bash`, and `zsh`. Function names come from the `name` field on the function's word; variable assignments and commands label the same way, so no fallback rules are needed.

### Detected concepts

| tree-sitter node type | Canonical concept |
| - | - |
| `function_definition` | Function |
| `command` | CallExpression |
| `command_name` | identifier |
| `variable_assignment` | Variable |
| `simple_expansion` | Variable |
| `declaration_command` | Variable |
| `if_statement` | IfBlock |
| `for_statement` | ForLoop |
| `while_statement` | WhileLoop |
| `case_statement` | SwitchBlock |
| `string` | string\_literal |
| `number` | number\_literal |

### Example

Renaming a function:

```bash theme={null}
# old.sh
total() { echo hi; }
```

```bash theme={null}
# new.sh
sum() { echo hi; }
```

Running `differens old.sh new.sh`:

```
~ renamed function `total` to `sum`
```

### Known limitations

* Heredoc bodies are strings; edits inside them report as value changes.
* Command substitutions and pipelines are structure: a pipeline reordering reports as a reorder of call expressions.