Git – 更新操作

修改现有的功能

汤姆执行了克隆操作，发现了一个新的文件string.c，他想知道是谁把这个文件添加到仓库的，有什么目的，所以，他执行了 git log 命令。

[tom@CentOS ~]$ git clone gituser@git.server.com: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内创建一个新目录。他将目录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 <jerry@tutorialspoint.com>
Date: Wed Sep 11 08:05:26 2013 +0530

Changed return type of my_strlen to size_t


commit 19ae20683fc460db7d127cf201a1429523b0e319
Author: Tom Cat <tom@tutorialspoint.com>
Date: Wed Sep 11 07:32:56 2013 +0530

Initial commit

在观察了日志之后，他意识到文件string.c是由Jerry添加的，用于实现基本的字符串操作。他对Jerry的代码感到好奇。于是，他在文本编辑器中打开string.c，立即发现了一个错误。在my_strlen函数中，Jerry没有使用一个常数指针。所以，他决定修改Jerry的代码。修改之后，代码看起来如下

[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;
}

测试之后，他提交了他的变化。

[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 <tom@tutorialspoint.com>
Date: Wed Sep 11 08:32:07 2013 +0530

Changed char pointer to const char pointer


commit d1e19d316224cddc437e3ed34ec3c931ad803958
Author: Jerry Mouse <jerry@tutorialspoint.com>
Date: Wed Sep 11 08:05:26 2013 +0530

Changed return type of my_strlen to size_t


commit 19ae20683fc460db7d127cf201a1429523b0e319
Author: Tom Cat <tom@tutorialspoint.com>
Date: Wed Sep 11 07:32:56 2013 +0530
Initial commit

汤姆使用git push命令来推送他的改动。

[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 gituser@git.server.com: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。所以他修改了string.c，修改后的文件看起来如下

[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;
   }
}

经过测试，他已经准备好推动他的变革。

[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，他通过查看日志信息来验证提交。

[jerry@CentOS project]$ git log

上述命令将产生以下结果 –

commit e944e5aab74b26e7447d3281b225309e4e59efcd
Author: Jerry Mouse <jerry@tutorialspoint.com>
Date: Wed Sep 11 08:41:42 2013 +0530

Added my_strcpy function


commit d1e19d316224cddc437e3ed34ec3c931ad803958
Author: Jerry Mouse <jerry@tutorialspoint.com>
Date: Wed Sep 11 08:05:26 2013 +0530

Changed return type of my_strlen to size_t


commit 19ae20683fc460db7d127cf201a1429523b0e319
Author: Tom Cat <tom@tutorialspoint.com>
Date: Wed Sep 11 07:32:56 2013 +0530

Initial commit

杰里对这些变化很满意，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 gituser@git.server.com:project.git
! [rejected]
master −> master (non-fast-forward)
error: failed to push some refs to 'gituser@git.server.com: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Git不允许Jerry推送他的修改。因为Git发现远程仓库和Jerry的本地仓库并不同步。正因为如此，他可能会失去项目的历史。为了避免这种混乱的局面，Git 使这次操作失败。现在，Jerry 必须先更新本地仓库，然后才可以推送自己的修改。

获取最新变化

Jerry 执行了 git pull 命令，将他的本地仓库与远程仓库同步。

[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

拉取操作后，Jerry检查了日志信息，发现Tom的提交细节，提交ID为 cea2c000f53ba99508c5959e3e12fff493ba6f69

[jerry@CentOS project]$ git log

上述命令将产生以下结果 –

commit e86f0621c2a3f68190bba633a9fe6c57c94f8e4f
Author: Jerry Mouse <jerry@tutorialspoint.com>
Date: Wed Sep 11 08:41:42 2013 +0530

Added my_strcpy function


commit cea2c000f53ba99508c5959e3e12fff493ba6f69
Author: Tom Cat <tom@tutorialspoint.com>
Date: Wed Sep 11 08:32:07 2013 +0530

Changed char pointer to const char pointer


commit d1e19d316224cddc437e3ed34ec3c931ad803958
Author: Jerry Mouse <jerry@tutorialspoint.com>
Date: Wed Sep 11 08:05:26 2013 +0530

Changed return type of my_strlen to size_t


commit 19ae20683fc460db7d127cf201a1429523b0e319
Author: Tom Cat <tom@tutorialspoint.com>
Date: Wed Sep 11 07:32:56 2013 +0530
Initial commit

现在，Jerry的本地版本库已经与远程版本库完全同步了。所以他可以安全地推送他的修改。

[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 gituser@git.server.com:project.git
cea2c00..e86f062 master −> master