# grit blame

> Show who last modified each line of a file.

## Synopsis

```text
grit blame [--rev <commit>] [-L START,END] <file>
```

## Description

Walks history for one file and prints each line with the commit that last modified it, the author, when that commit was made, and the line number in the blamed revision.

## Options

| Option | Description |
| --- | --- |
| `--rev <commit>` | Blame the file as it existed at this revision (branch, tag, oid, `HEAD~N`, …). Defaults to `HEAD`. |
| `-L START,END` | Limit output to an inclusive 1-based line range in the final file. |
| `--lines` | Same as `-L` (long form). |

## Examples

Blame a file at `HEAD`:

```console
$ grit blame src/lib.rs
a1b2c3d (ada 2 days ago    1) use std::io;
f4e5d6c (bob 1 week ago    2) fn main() {
```

Blame an older revision and a slice of lines:

```console
$ grit blame --rev=v1.0 -L 10,25 README.md
```

Scripting with JSON:

```console
$ grit blame --json story.txt
```

## JSON output

Pass `--json` for stable, scripting-friendly output:

| Field | Type | Meaning |
| ----- | ---- | ------- |
| `file` | string | Repository-relative path that was blamed. |
| `rev` | string | Full commit oid of the start revision. |
| `lines` | array | One record per line (after any `-L` filter), in final-line order. |
| `lines[].commit` | string | Full commit oid for the line. |
| `lines[].original_line` | number | 1-based line number in the originating commit. |
| `lines[].final_line` | number | 1-based line number in the blamed revision. |
| `lines[].content` | string | Line text. |
| `commits` | object | Map of commit oid → metadata for every line. |
| `commits.<oid>.author` | string | Author identity line. |
| `commits.<oid>.author_time` | number | Author time (Unix seconds). |
| `commits.<oid>.summary` | string | First line of the commit message. |

Example:

```json
{
  "file": "story.txt",
  "rev": "92501f188ae0815af09a0cef6e121eddda4113cf",
  "lines": [
    {
      "commit": "919c45f33de5e5c0bd05f8ffb089f697f4644976",
      "original_line": 1,
      "final_line": 1,
      "content": "alpha ONE"
    }
  ],
  "commits": {
    "919c45f33de5e5c0bd05f8ffb089f697f4644976": {
      "author": "Blame Test <blame@example.com> 1700000000 +0000",
      "author_time": 1700000000,
      "summary": "init"
    }
  }
}
```

## Markdown output

Pass `--markdown` for a table suited to agents: columns are final line, short commit, author, date, original line, and content.

## See also

[grit log](https://grit-scm.com/docs/log/index.md), [grit show](https://grit-scm.com/docs/show/index.md)