在本文章教程中，我们将演示如何查看 Git 存储库的文件和提交文件记录，并对存储库中的文件作修改和提交。
注意：在开始学习本教程之前，先克隆一个存储库，有关如何克隆存储库，请参考： Git克隆操作
在上一步中，我们已经修改了 main.py 文件中的代码，在代码中定义了两个变量并提交代码，但是要再次添加和修改main.py 文件中的代码，实现新功能：求两个变量相加值。修改提交的操作更改包含提交消息的最后一个提交; 它创建一个新的提交ID。
在修改操作之前，检查提交日志，如下命令所示：
$ git log
commit d757c8e92ad6053db294100c77075865f829b7ac
Author: your_name
Date: Fri Jul 7 23:04:16 2017 +0800
define two var a & b
commit be24e214620fa072efa877e1967571731c465884
Author: your_name
Date: Fri Jul 7 18:58:16 2017 +0800
？？mark
commit 5eccf92e28eae94ec5fce7c687f6f92bf32a6a8d
Author: your_name
Date: Fri Jul 7 18:52:06 2017 +0800
this is main.py file commit mark use -m option
commit 6e5f31067466795c522b01692871f202c26ff948
Author: your_name
Date: Fri Jul 7 18:42:43 2017 +0800
this is main.py file commit mark without use "-m" option
commit 290342c270bc90f861ccc3d83afa920169e3b07e
Author: Maxsu <769728683@qq.com>
Date: Fri Jul 7 16:55:12 2017 +0800
Initial commit
下面我们打开文件：main.py 加入以下两行：
c = a + b
print("The value of c is ", c)
更正操作提交新的更改，并查看提交日志。首先查看状态，如下命令：
$ git status
On branch master
Your branch is ahead of 'origin/master' by 4 commits.
(use "git push" to publish your local commits)
Changes not staged for commit:
(use "git add ..." to update what will be committed)
(use "git checkout -- ..." to discard changes in working directory)
modified: main.py
no changes added to commit (use "git add" and/or "git commit -a")
添加文件并查看状态，如下命令：
$ git add main.py
Administrator@MY-PC /D/worksp/sample (master)
$ git status
On branch master
Your branch is ahead of 'origin/master' by 4 commits.
(use "git push" to publish your local commits)
Changes to be committed:
(use "git reset HEAD ..." to unstage)
modified: main.py
提交更改的文件，如下所示：
$ git commit --amend -m "add the sum of a & b "
[master 51de0f0] add the sum of a & b
1 file changed, 5 insertions(+), 1 deletion(-)
现在，使用 git log命令显示将显示新的提交消息与新的提交ID(51de0f02eb48ed6b84a732512f230028d866b1ea)，最近一次提交的放前面：
$ git log
commit 51de0f02eb48ed6b84a732512f230028d866b1ea
Author: your_name
Date: Fri Jul 7 23:04:16 2017 +0800
add the sum of a & b
commit be24e214620fa072efa877e1967571731c465884
Author: your_name
Date: Fri Jul 7 18:58:16 2017 +0800
？？mark
commit 5eccf92e28eae94ec5fce7c687f6f92bf32a6a8d
Author: your_name
Date: Fri Jul 7 18:52:06 2017 +0800
this is main.py file commit mark use -m option
commit 6e5f31067466795c522b01692871f202c26ff948
Author: your_name
Date: Fri Jul 7 18:42:43 2017 +0800
this is main.py file commit mark without use "-m" option
commit 290342c270bc90f861ccc3d83afa920169e3b07e
Author: Maxsu <769728683@qq.com>
Date: Fri Jul 7 16:55:12 2017 +0800
Initial commit