接着上面的git版本管理系列(一)，繼續完成git的接下來的操作
我們繼續修改readme.txt文件
first add.
second add something.
使用git status 查看當前倉庫的狀態
nelsen-mac:learngit mac$ 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: readme.md //告訴我們，這個文件被修改了
no changes added to commit (use "git add" and/or "git commit -a")
還可以使用git diff這個命令查看修改的不同之處
nelsen-mac:learngit mac$ git diff
diff --git a/readme.md b/readme.md
index d107973..9a55b32 100644
--- a/readme.md
+++ b/readme.md
@@ -1 +1,2 @@
first add.
+second add something.
然後再次添加我們的文件到本地暫存區
nelsen-mac:learngit mac$ git add readme.md
nelsen-mac:learngit mac$ git status
On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: readme.md
下一步，就可以放心地提交了
nelsen-mac:learngit mac$ git commit -m'second add.'
[master c52921e] second add.
1 file changed, 1 insertion(+)
再使用 git status 查看當前倉庫的狀態，下面的提示說明當前的倉庫沒有新的需要提交的修改，工作目錄是乾淨（working tree clean）的
nelsen-mac:learngit mac$ git status
On branch master
nothing to commit, working tree clean