Git更新操作的方法

修改现有功能

Tom 执行克隆操作并找到一个新文件 string.c。他想知道谁将此文件添加到存储库中以及出于什么目的，因此，他执行了git log命令。

[tom@CentOS ~]$ git clone [email protected]:project.git

上述命令将产生以下结果

Initialized empty Git repository in /home/tom/project/.git/
remote: Counting objects: 6, done.
remote: Compressing objects: 100% (4/4), done.
Receiving objects: 100% (6/6), 726 bytes, done.
remote: Total 6 (delta 0), reused 0 (delta 0)

克隆操作将在当前工作目录中创建一个新目录。他将目录更改为新创建的目录并执行git log命令。

[tom@CentOS ~]$ cd project/
[tom@CentOS project]$ git log

上述命令将产生以下结果

commit d1e19d316224cddc437e3ed34ec3c931ad803958
Author: Jerry Mouse <[email protected]>
Date: Wed Sep 11 08:05:26 2013 +0530
Changed return type of my_strlen to size_t
commit 19ae20683fc460db7d127cf201a1429523b0e319
Author: Tom Cat <[email protected]>
Date: Wed Sep 11 07:32:56 2013 +0530
Initial commit

观察日志后，他意识到文件string.c是Jerry添加的，用于实现基本的字符串操作。他对 Jerry 的代码很好奇。于是他在文本编辑器中打开 string.c 并立即发现了一个错误。在 my_strlen 函数中，Jerry 没有使用常量指针。因此，他决定修改 Jerry 的代码。修改后，代码如下

[tom@CentOS project]$ git diff

上述命令将产生以下结果

diff --git a/string.c b/string.c
index 7da2992..32489eb 100644
--- a/string.c
+++ b/string.c
@@ -1,8 +1,8 @@
#include <stdio.h>
-size_t my_strlen(char *s)
+size_t my_strlen(const char *s)
{
   - char *p = s;
   + const char *p = s;
   while (*p)
   ++p;
}

经过测试，他提交了他的更改。

[tom@CentOS project]$ git status -s
M string.c
?? string
[tom@CentOS project]$ git add string.c
[tom@CentOS project]$ git commit -m 'Changed char pointer to const char pointer'
[master cea2c00] Changed char pointer to const char pointer
1 files changed, 2 insertions(+), 2 deletions(-)
[tom@CentOS project]$ git log

上述命令将产生以下结果

commit cea2c000f53ba99508c5959e3e12fff493b
Author: Tom Cat <[email protected]>
Date: Wed Sep 11 08:32:07 2013 +0530
Changed char pointer to const char pointer
commit d1e19d316224cddc437e3ed34ec3c931ad803958
Author: Jerry Mouse <[email protected]>
Date: Wed Sep 11 08:05:26 2013 +0530
Changed return type of my_strlen to size_t
commit 19ae20683fc460db7d127cf201a1429523b0e319
Author: Tom Cat <[email protected]>
Date: Wed Sep 11 07:32:56 2013 +0530
Initial commit

Tom 使用 git push 命令推送他的更改。

[tom@CentOS project]$ git push origin master

上述命令将产生以下结果

Counting objects: 5, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 336 bytes, done.
Total 3 (delta 1), reused 0 (delta 0)
To [email protected]:project.git
d1e19d3..cea2c00 master −> master

添加新功能

同时，Jerry 决定实现字符串比较功能。于是他修改了string.c。修改后，文件如下所示

[jerry@CentOS project]$ git diff

上述命令将产生以下结果

index 7da2992..bc864ed 100644
--- a/string.c
+++ b/string.c
30Git Tutorials
@@ -9,9 +9,20 @@ size_t my_strlen(char *s)
return (p -s );
}
+char *my_strcpy(char *t, char *s)
+
{
   +
   char *p = t;
   +
   + while (*t++ = *s++)
   + ;
   +
   +
   return p;
   +
}
+
int main(void)
{
   int i; 
   +
   char p1[32];
   char *s[] = 
   {
      "Git tutorials",
      "Tutorials Point"
      @@ -20,5 +31,7 @@ int main(void)
      for (i = 0; i < 2; ++i)
      printf("string lenght of %s = %lu\n", s[i], my_strlen(s[i]));
      +
      printf("%s\n", my_strcpy(p1, "Hello, World !!!"));
      +
      return 0;
   }
}

在测试之后，他准备好推动他的改变。

[jerry@CentOS project]$ git status -s
M string.c
?? string
[jerry@CentOS project]$ git add string.c
[jerry@CentOS project]$ git commit -m "Added my_strcpy function"
[master e944e5a] Added my_strcpy function
1 files changed, 13 insertions(+), 0 deletions(-)

在推送操作之前，他通过查看日志消息来验证提交。

[jerry@CentOS project]$ git log

上述命令将产生以下结果

commit e944e5aab74b26e7447d3281b225309e4e59efcd
Author: Jerry Mouse <[email protected]>
Date: Wed Sep 11 08:41:42 2013 +0530
Added my_strcpy function
commit d1e19d316224cddc437e3ed34ec3c931ad803958
Author: Jerry Mouse <[email protected]>
Date: Wed Sep 11 08:05:26 2013 +0530
Changed return type of my_strlen to size_t
commit 19ae20683fc460db7d127cf201a1429523b0e319
Author: Tom Cat <[email protected]>
Date: Wed Sep 11 07:32:56 2013 +0530
Initial commit

Jerry 对这些变化很满意，他想推动他的变化。

[jerry@CentOS project]$ git push origin master

上述命令将产生以下结果

To [email protected]:project.git
! [rejected]
master −> master (non-fast-forward)
error: failed to push some refs to '[email protected]:project.git'
To prevent you from losing history, non-fast-forward updates were rejected
Merge the remote changes before pushing again. See the 'Note about
fast-forwards' section of 'git push --help' for details.

但是 Git 不允许 Jerry 推送他的更改。因为 Git 发现远程仓库和 Jerry 的本地仓库不同步。正因为如此，他可能会丢失项目的历史记录。为了避免这种混乱，Git 失败了这个操作。现在，Jerry 必须先更新本地存储库，然后才能推送自己的更改。

获取最新更改

Jerry 执行 git pull 命令以将他的本地存储库与远程存储库同步。

[jerry@CentOS project]$ git pull

上述命令将产生以下结果

remote: Counting objects: 5, done.
remote: Compressing objects: 100% (3/3), done.
remote: Total 3 (delta 1), reused 0 (delta 0)
Unpacking objects: 100% (3/3), done.
From git.server.com:project
d1e19d3..cea2c00 master −> origin/master
First, rewinding head to replay your work on top of it...
Applying: Added my_strcpy function

拉操作后，Jerry 检查日志消息并找到 Tom 提交 ID 为cea2c000f53ba99508c5959e3e12fff493ba6f69的提交的详细信息

[jerry@CentOS project]$ git log

上述命令将产生以下结果

commit e86f0621c2a3f68190bba633a9fe6c57c94f8e4f
Author: Jerry Mouse <[email protected]>
Date: Wed Sep 11 08:41:42 2013 +0530
Added my_strcpy function
commit cea2c000f53ba99508c5959e3e12fff493ba6f69
Author: Tom Cat <[email protected]>
Date: Wed Sep 11 08:32:07 2013 +0530
Changed char pointer to const char pointer
commit d1e19d316224cddc437e3ed34ec3c931ad803958
Author: Jerry Mouse <[email protected]>
Date: Wed Sep 11 08:05:26 2013 +0530
Changed return type of my_strlen to size_t
commit 19ae20683fc460db7d127cf201a1429523b0e319
Author: Tom Cat <[email protected]>
Date: Wed Sep 11 07:32:56 2013 +0530
Initial commit

现在，Jerry 的本地存储库与远程存储库完全同步。所以他可以安全地推送他的更改。

[jerry@CentOS project]$ git push origin master

上述命令将产生以下结果

Counting objects: 5, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 455 bytes, done.
Total 3 (delta 1), reused 0 (delta 0)
To [email protected]:project.git
cea2c00..e86f062 master −> master

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