# Git 명령어에 따른 .git 내부 구조 변화(1부)

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## <span style="white-space: pre-wrap;">1. </span>`<span class="editor-theme-code">git merge</span>`<span style="white-space: pre-wrap;"> 시 내부 변화</span>

### 1.1 예시 명령어

```bash
git checkout main
git merge feature
```

### <span style="white-space: pre-wrap;">1.2 </span>`<span class="editor-theme-code">.git</span>`<span style="white-space: pre-wrap;"> 내부 변화</span>

<table id="bkmrk-%EA%B5%AC%EC%84%B1-%EC%9A%94%EC%86%8C%EB%B3%80%ED%99%94-%EB%82%B4%EC%9A%A9.git%2Fobjec"><colgroup><col></col><col></col></colgroup><tbody><tr><th>구성 요소

</th><th>변화 내용

</th></tr><tr><td>`<span class="editor-theme-code">.git/objects/</span>`

</td><td><span style="white-space: pre-wrap;">병합 결과로 새로운 </span>****merge commit****<span style="white-space: pre-wrap;"> 객체 생성</span>

</td></tr><tr><td>`<span class="editor-theme-code">.git/refs/heads/main</span>`

</td><td>브랜치 포인터가 merge 커밋으로 이동

</td></tr><tr><td>`<span class="editor-theme-code">.git/HEAD</span>`

</td><td><span style="white-space: pre-wrap;">여전히 </span>`<span class="editor-theme-code">ref: refs/heads/main</span>`<span style="white-space: pre-wrap;"> 유지</span>

</td></tr><tr><td>`<span class="editor-theme-code">.git/MERGE_HEAD</span>`

</td><td>병합 대상 커밋(`<span class="editor-theme-code">feature</span>`) 해시 저장 (병합 중일 때 생성됨)

</td></tr><tr><td>`<span class="editor-theme-code">.git/logs/HEAD</span>`

</td><td>HEAD의 이동 이력 반영됨 (reflog)

</td></tr></tbody></table>

### 1.3 도식 예시

```
A---B---C ← main
     \    
      D---E ← feature

▶ git merge feature

결과:

A---B---C-------M (merge commit) ← main, HEAD
     \         /
      D---E
```

---

## <span style="white-space: pre-wrap;">2. </span>`<span class="editor-theme-code">git rebase</span>`<span style="white-space: pre-wrap;"> 시 내부 변화</span>

### 2.1 예시 명령어

```bash
git checkout feature
git rebase main
```

### <span style="white-space: pre-wrap;">2.2 </span>`<span class="editor-theme-code">.git</span>`<span style="white-space: pre-wrap;"> 내부 변화</span>

<table id="bkmrk-%EA%B5%AC%EC%84%B1-%EC%9A%94%EC%86%8C%EB%B3%80%ED%99%94-%EB%82%B4%EC%9A%A9.git%2Fobjec-1"><colgroup><col></col><col></col></colgroup><tbody><tr><th>구성 요소

</th><th>변화 내용

</th></tr><tr><td>`<span class="editor-theme-code">.git/objects/</span>`

</td><td>`<span class="editor-theme-code">feature</span>`<span style="white-space: pre-wrap;">의 커밋들을 기반 변경 후 새 커밋으로 </span>****재작성****

</td></tr><tr><td>`<span class="editor-theme-code">.git/refs/heads/feature</span>`

</td><td>브랜치가 새 커밋들로 덮어씀

</td></tr><tr><td>`<span class="editor-theme-code">.git/REBASE_HEAD</span>`

</td><td>리베이스 기준 커밋을 기록

</td></tr><tr><td>`<span class="editor-theme-code">.git/HEAD</span>`

</td><td><span style="white-space: pre-wrap;">여전히 </span>`<span class="editor-theme-code">ref: refs/heads/feature</span>`

</td></tr><tr><td>`<span class="editor-theme-code">.git/logs/HEAD</span>`

</td><td>HEAD의 커밋 재작성 이력 반영됨

</td></tr></tbody></table>

### 2.3 도식 예시

```
main:    A---B---C
feature:           D---E

▶ git rebase main

결과:
main:    A---B---C
feature:           D'---E' ← HEAD
```

> <span style="white-space: pre-wrap;">원래 커밋 D, E는 삭제되지 않고 </span>`<span class="editor-theme-code">.git/objects</span>`에 보존됨

---

## <span style="white-space: pre-wrap;">3. </span>`<span class="editor-theme-code">git reset</span>`<span style="white-space: pre-wrap;"> 시 내부 변화</span>

### 3.1 예시 명령어

```bash
git reset --hard HEAD~1
```

### <span style="white-space: pre-wrap;">3.2 </span>`<span class="editor-theme-code">.git</span>`<span style="white-space: pre-wrap;"> 내부 변화</span>

<table id="bkmrk-%EA%B5%AC%EC%84%B1-%EC%9A%94%EC%86%8C%EB%B3%80%ED%99%94-%EB%82%B4%EC%9A%A9.git%2Frefs%2F"><colgroup><col></col><col></col></colgroup><tbody><tr><th>구성 요소

</th><th>변화 내용

</th></tr><tr><td>`<span class="editor-theme-code">.git/refs/heads/main</span>`

</td><td>브랜치 포인터가 이전 커밋으로 이동

</td></tr><tr><td>`<span class="editor-theme-code">.git/HEAD</span>`

</td><td><span style="white-space: pre-wrap;">여전히 </span>`<span class="editor-theme-code">ref: refs/heads/main</span>`

</td></tr><tr style="height: 10px;"><td>`<span class="editor-theme-code">.git/index</span>`

</td><td>되돌린 커밋 시점으로 스테이징 영역 초기화

</td></tr><tr><td>작업 디렉토리

</td><td>`<span class="editor-theme-code">--hard</span>`인 경우 파일도 초기화

</td></tr><tr><td>`<span class="editor-theme-code">.git/ORIG_HEAD</span>`

</td><td>이전 HEAD 커밋 해시를 저장

</td></tr><tr><td>`<span class="editor-theme-code">.git/logs/HEAD</span>`

</td><td>이동 전후 이력 기록됨

</td></tr></tbody></table>

### 3.3 도식 예시

```
A---B---C ← main, HEAD
        ↑
     ORIG_HEAD

▶ git reset --hard B

결과:

A---B ← main, HEAD
```

---

## 4. 특수 HEAD 파일 요약

<table id="bkmrk-%ED%8C%8C%EC%9D%BC-%EC%9D%B4%EB%A6%84%EC%83%9D%EC%84%B1-%EC%8B%9C%EC%A0%90%EC%84%A4%EB%AA%85.git%2Fmer"><colgroup><col></col><col></col><col></col></colgroup><tbody><tr><th>파일 이름

</th><th>생성 시점

</th><th>설명

</th></tr><tr><td>`<span class="editor-theme-code">.git/MERGE_HEAD</span>`

</td><td>`<span class="editor-theme-code">git merge</span>`<span style="white-space: pre-wrap;"> 수행 중</span>

</td><td>병합 대상 커밋 해시 저장

</td></tr><tr><td>`<span class="editor-theme-code">.git/REBASE_HEAD</span>`

</td><td>`<span class="editor-theme-code">git rebase</span>`<span style="white-space: pre-wrap;"> 수행 중</span>

</td><td>기준 커밋 해시 저장

</td></tr><tr><td>`<span class="editor-theme-code">.git/ORIG_HEAD</span>`

</td><td>`<span class="editor-theme-code">git reset</span>`<span style="white-space: pre-wrap;">, </span>`<span class="editor-theme-code">merge</span>`<span style="white-space: pre-wrap;"> 등</span>

</td><td>리셋 전 커밋 백업

</td></tr><tr><td>`<span class="editor-theme-code">.git/FETCH_HEAD</span>`

</td><td>`<span class="editor-theme-code">git fetch</span>`<span style="white-space: pre-wrap;"> 이후</span>

</td><td>원격에서 받아온 커밋들 정보

</td></tr><tr><td>`<span class="editor-theme-code">.git/CHERRY_PICK_HEAD</span>`

</td><td>`<span class="editor-theme-code">git cherry-pick</span>`<span style="white-space: pre-wrap;"> 중 충돌 시</span>

</td><td>적용 대상 커밋 기록

</td></tr></tbody></table>

---

## 5. 요약 비교표

<table id="bkmrk-%EB%AA%85%EB%A0%B9%EC%96%B4%EC%BB%A4%EB%B0%8B-%EC%9D%B4%EB%8F%99%EB%B8%8C%EB%9E%9C%EC%B9%98-%EC%9D%B4%EB%8F%99head-%EB%B3%80"><colgroup><col></col><col></col><col></col><col></col><col></col><col></col></colgroup><tbody><tr><th>명령어

</th><th>커밋 이동

</th><th>브랜치 이동

</th><th>HEAD 변경

</th><th>디렉토리 영향

</th><th>특수 파일 생성

</th></tr><tr><td>`<span class="editor-theme-code">merge</span>`

</td><td>⭕

</td><td>⭕

</td><td>⭕

</td><td>충돌 시 변동 있음

</td><td>`<span class="editor-theme-code">MERGE_HEAD</span>`

</td></tr><tr><td>`<span class="editor-theme-code">rebase</span>`

</td><td>⭕ (rewrite)

</td><td>⭕

</td><td>⭕

</td><td>충돌 시 변동 있음

</td><td>`<span class="editor-theme-code">REBASE_HEAD</span>`

</td></tr><tr><td>`<span class="editor-theme-code">reset --hard</span>`

</td><td>⭕ (이전 커밋으로)

</td><td>⭕

</td><td>⭕

</td><td>✔️ 완전 초기화

</td><td>`<span class="editor-theme-code">ORIG_HEAD</span>`

</td></tr></tbody></table>

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