[git] 细说commit (git add/commit/diff/rm/reset 以及 index 的概念)

http://kasicass.blog.163.com/blog/static/39561920133294219374/

创建测试仓库

$ git init

$ echo "line one" >> foo.txt

$ git add foo.txt

$ git commit -m "first commit"

 

说说 add/reset/diff

我们修改一下 foo.txt，看看效果。

$ echo "line two" >> foo.txt

$ git diff

diff --git a/foo.txt b/foo.txt

index 2d00bd5..e5c5c55 100644

--- a/foo.txt

+++ b/foo.txt

@@ -1 +1,2 @@

 line one

+line two

此时，git diff 可以看到修改内容，但不能 git commit 提交之。

修改的内容，默认会处于 unstage 状态（修改了，但commit不提交），git status 可以看到状态。

$ git status

# On branch master

# Changes not staged for commit:

#   (use "git add <file>..." to update what will be committed)

#   (use "git checkout -- <file>..." to discard changes in working directory)

#

# modified:   foo.txt

#

no changes added to commit (use "git add" and/or "git commit -a")

如果想提交，需要显式 git add 一下。修改的文件状态会变为 staged。

然后 git diff 就看不到修改内容了，而 git diff --cached 才能看到。

当然，也可以用 git commit -a foo.txt 直接提交，而不需要显式 git add foo.txt。

$ git add foo.txt

$ git diff

$ git diff --cached

diff --git a/foo.txt b/foo.txt

index 2d00bd5..e5c5c55 100644

--- a/foo.txt

+++ b/foo.txt

@@ -1 +1,2 @@

 line one

+line two

$ git status

# On branch master

# Changes to be committed:

#   (use "git reset HEAD <file>..." to unstage)

#

# modified:   foo.txt

#

这个优点，同时修改了两处代码，只想提交某一处修改，则显式 git add 想提交的文件即可。

已经 git add 的文件，可以通过  git reset <file> 来 un-add。

$ git reset foo.txt

Unstaged changes after reset:

M foo.txt

$ git diff --cached

$ git diff

diff --git a/foo.txt b/foo.txt

index 2d00bd5..e5c5c55 100644

--- a/foo.txt

+++ b/foo.txt

@@ -1 +1,2 @@

 line one

+line two

如果要将 foo.txt 恢复到修改前的状态，可以 git checkout。

$ git checkout foo.txt

$ git diff

$ git status

# On branch master

nothing to commit (working directory clean)

 

rm、mv 和 log --follow

先给仓库再加入个文件 bar.txt

$ echo "barbar" >> bar.txt

$ git add bar.txt

$ git status

# On branch master
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# new file: bar.txt
#

此时，bar.txt 并没有通过 git commit 提交到仓库，如果想 unadd foo.txt，需要：

$ git rm --cached bar.txt

rm 'bar.txt'

$ git status

# On branch master

# Untracked files:

#   (use "git add <file>..." to include in what will be committed)

#

# bar.txt

nothing added to commit but untracked files present (use "git add" to track)

顺便说一下，对于未 git add 的文件，处于 untracked 状态。git commit 不会提交 untracked 的文件。

对于已经 git add && commit 的文件，直接通过 git rm && commit 将起删除即可。

$ git add bar.txt

$ git commit -m "add bar.txt"

[master 0fa635d] add bar.txt

 1 file changed, 1 insertion(+)

 create mode 100644 bar.txt

$ git rm bar.txt

rm 'bar.txt'

$ git commit -m "remove bar.txt"

[master fcdfd15] remove bar.txt

 1 file changed, 1 deletion(-)

 delete mode 100644 bar.txt

$ ls

foo.txt

我们还可以通过 git mv 来重命名文件。而 git log 的 --follow 参数，可以查看到文件 mv 之前的修改记录。

$ git mv foo.txt rename.txt

$ git commit -m "rename it"

[master 788b36d] rename it

 1 file changed, 0 insertions(+), 0 deletions(-)

 rename foo.txt => rename.txt (100%)

$ git log rename.txt

commit 788b36d799e4f8cea226b29efe13e62ecadea7b8

Author: kasicass <[e-mail]>

Date:   Thu Apr 4 10:29:47 2013 +0800

 

    rename it

$ git log --follow rename.txt 

commit 788b36d799e4f8cea226b29efe13e62ecadea7b8

Author: kasicass <[e-mail]>

Date:   Thu Apr 4 10:29:47 2013 +0800

 

    rename it

 

commit 3cc14639388770d01eb8db5fbe57f917584508bf

Author: kasicass <[e-mail]>

Date:   Thu Apr 4 10:10:42 2013 +0800

 

    first commit

 

深入理解 index

git 中 index 的概念，就是“当前要提交的内容（tracks what you want to commit）”。

我们先来修改一下 rename.txt 并 git add 之。

$ echo "line two" >> rename.txt 

$ git add rename.txt 

$ git diff --cached

diff --git a/rename.txt b/rename.txt

index 2d00bd5..e5c5c55 100644

--- a/rename.txt

+++ b/rename.txt

@@ -1 +1,2 @@

 line one

+line two

我们再修改一下 rename.txt 的内容。

你会发现 git diff 和 git diff --cached 的结果是不一样的。

$ echo "line three" >> rename.txt 

$ git diff

diff --git a/rename.txt b/rename.txt

index e5c5c55..0c2aa38 100644

--- a/rename.txt

+++ b/rename.txt

@@ -1,2 +1,3 @@

 line one

 line two

+line three

$ git diff --cached

diff --git a/rename.txt b/rename.txt

index 2d00bd5..e5c5c55 100644

--- a/rename.txt

+++ b/rename.txt

@@ -1 +1,2 @@

 line one

+line two

对的，git diff --cached 是查看即将提交到仓库的变化，而 git diff 是查看当前与 --cached 的变化。

要想提交最新修改，还得再 git add rename.txt 一次。

$ git add rename.txt 

$ git diff

$ git diff --cached

diff --git a/rename.txt b/rename.txt

index 2d00bd5..0c2aa38 100644

--- a/rename.txt

+++ b/rename.txt

@@ -1 +1,3 @@

 line one

+line two

+line three

所以，可以理解为 current diff ==> index cache ==> repo。

当前的修改，通过 git add 提交到 index cache，再通过 git commit 正式提交到 repo。

 

ps.

如果 git commit 没有 -m 参数，git 会启用 GIT_EDITOR 来编辑 message。

$ export GIT_EDITOR=vim