修改现有功能

Tom执行克隆操作并找到一个新文件string.c。他想知道是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 gituser@git.server.com:project.git

上面的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

上面的命令将产生以下结果-

commit d1e19d316224cddc437e3ed34ec3c931ad803958Author: Jerry Mouse <jerry@tutorialspoint.com>Date: Wed Sep 11 08:05:26 2013 +0530Changed return type of my_strlen to size_tcommit 19ae20683fc460db7d127cf201a1429523b0e319Author: Tom Cat <tom@tutorialspoint.com>Date: Wed Sep 11 07:32:56 2013 +0530Initial commit

观察日志后，他意识到Jerry添加了文件string.c来实现基本的字符串操作。他对杰里的代码感到好奇。因此，他在文本编辑器中打开string.c并立即发现一个错误。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，代码如下所示-

[tom@CentOS project]$ git diff

上面的命令将产生以下结果-

diff --git a/string.c b/string.cindex 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;}

经过测试后，他提交了更改。

[tom@CentOS project]$ git status -sM 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 pointer1 files changed, 2 insertions(+), 2 deletions(-)[tom@CentOS project]$ git log

上面的命令将产生以下结果-

commit cea2c000f53ba99508c5959e3e12fff493bAuthor: Tom Cat <tom@tutorialspoint.com>Date: Wed Sep 11 08:32:07 2013 +0530Changed char pointer to const char pointercommit d1e19d316224cddc437e3ed34ec3c931ad803958Author: Jerry Mouse <jerry@tutorialspoint.com>Date: Wed Sep 11 08:05:26 2013 +0530Changed return type of my_strlen to size_tcommit 19ae20683fc460db7d127cf201a1429523b0e319Author: Tom Cat <tom@tutorialspoint.com>Date: Wed Sep 11 07:32:56 2013 +0530Initial commit

汤姆使用git push命令来推送更改。

[tom@CentOS project]$ git push origin master

上面的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.gitd1e19d3..cea2c00 master −> master

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

[jerry@CentOS project]$ git diff

上面的命令将产生以下结果-

index 7da2992..bc864ed 100644--- a/string.c+++ b/string.c30Git 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;   }}

经过测试后，他准备推动自己的改变。

[jerry@CentOS project]$ git status -sM 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 function1 files changed, 13 insertions(+), 0 deletions(-)

在执行推送操作之前，他通过查看日志消息来验证提交。

[jerry@CentOS project]$ git log

上面的命令将产生以下结果-

commit e944e5aab74b26e7447d3281b225309e4e59efcdAuthor: Jerry Mouse <jerry@tutorialspoint.com>Date: Wed Sep 11 08:41:42 2013 +0530Added my_strcpy functioncommit d1e19d316224cddc437e3ed34ec3c931ad803958Author: Jerry Mouse <jerry@tutorialspoint.com>Date: Wed Sep 11 08:05:26 2013 +0530Changed return type of my_strlen to size_tcommit 19ae20683fc460db7d127cf201a1429523b0e319Author: Tom Cat <tom@tutorialspoint.com>Date: Wed Sep 11 07:32:56 2013 +0530Initial commit

杰瑞（Jerry）对这些变化感到满意，他想推动自己的变化。

[jerry@CentOS project]$ git push origin master

上面的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 rejectedMerge the remote changes before pushing again. See the 'Note aboutfast-forwards' section of 'git push --help' for details.

但是Git不允许Jerry推动他的改变。因为Git确定远程存储库和Jerry的本地存储库不同步。因此，他可能会丢失该项目的历史。为了避免这种混乱，Git使此操作失败。现在，Jerry必须先更新本地存储库，然后才能更新自己的更改。

获取最新更改

Jerry执行git pull命令以将其本地存储库与远程存储库同步。

[jerry@CentOS project]$ git pull

上面的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:projectd1e19d3..cea2c00 master −> origin/masterFirst, rewinding head to replay your work on top of it...Applying: Added my_strcpy function

拉动操作后，Jerry检查日志消息并找到具有提交ID cea2c000f53ba99508c5959e3e12fff493ba6f69的Tom提交的详细信息

[jerry@CentOS project]$ git log

上面的命令将产生以下结果-

commit e86f0621c2a3f68190bba633a9fe6c57c94f8e4fAuthor: Jerry Mouse <jerry@tutorialspoint.com>Date: Wed Sep 11 08:41:42 2013 +0530Added my_strcpy functioncommit cea2c000f53ba99508c5959e3e12fff493ba6f69Author: Tom Cat <tom@tutorialspoint.com>Date: Wed Sep 11 08:32:07 2013 +0530Changed char pointer to const char pointercommit d1e19d316224cddc437e3ed34ec3c931ad803958Author: Jerry Mouse <jerry@tutorialspoint.com>Date: Wed Sep 11 08:05:26 2013 +0530Changed return type of my_strlen to size_tcommit 19ae20683fc460db7d127cf201a1429523b0e319Author: Tom Cat <tom@tutorialspoint.com>Date: Wed Sep 11 07:32:56 2013 +0530Initial commit

现在，Jerry的本地存储库已与远程存储库完全同步。这样他就可以安全地推动自己的更改。

[jerry@CentOS project]$ git push origin master

上面的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.gitcea2c00..e86f062 master −> master