# Log & Diff

## 기록확인(log)

**log**는 **역사**라 생각하면 된다. `commit`했던 버전들의 기록을 확인 할 수 있다.

```
$ git log
commit c6ce442fa11b976aa717eeacd4dc05a501bfdda5
Author: dahye Jeong <wjdekgp1750@naver.com>
Date:   Thu Mar 23 17:28:55 2017 +0900

    first commit

    첫 커밋임!!
```

commit 뒤의 문자(c6ce442fa11b976aa717eeacd4dc05a501bfdda5)는 이 버전에 대한 식별자(hashcode)이다.

```
$ git log -p
commit c6ce442fa11b976aa717eeacd4dc05a501bfdda5
Author: dahye Jeong <wjdekgp1750@naver.com>
Date:   Thu Mar 23 17:28:55 2017 +0900

    first commit

    첫 커밋임!!

diff --git a/test1.html b/test1.html
new file mode 100644
index 0000000..58d93db
--- /dev/null
+++ b/test1.html
@@ -0,0 +1 @@
+<p>test</p>
```

어떠한 코드가 바꼈는지 알 수 있다.

## 비교(diff)

### Unstage(uncommit)된 수정사항 확인

```
$ git diff
```

### commit(stage)된 수정사항 확인

```
$ git diff --cached
```

```
$ git diff --staged
```

### 브랜치간 비교

```
$ git diff [브랜치1] [브랜치2]
```

```
git diff master practice
diff --git a/aa.txt b/aa.txt
index ec18514..4374318 100644
--- a/aa.txt
+++ b/aa.txt
@@ -1,5 +1,3 @@
 first commit

-log,diff비교해보자!!
-
-master브랜치야
\ No newline at end of file
+log,diff비교해보자!!
\ No newline at end of file
```

### commit간 비교

```
$ git diff <commit hash> <commit hash>
```

```
$  git diff 59f62dfcb5742b3712f4e2a20c7e2b41e995fef9 cbba34b0b53696b22e8bf24894755431eaf2f525
diff --git a/aa.txt b/aa.txt
index ec18514..4374318 100644
--- a/aa.txt
+++ b/aa.txt
@@ -1,5 +1,3 @@
 first commit

-log,diff비교해보자!!
-
-master브랜치야
\ No newline at end of file
+log,diff비교해보자!!
```

### 마지막 commit 과 그 전 commit 비교

```
$ git diff HEAD HEAD^
```

달라진 부분을 알려준다.


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