Git 简明教程
Git - Update Operation
Modify Existing Function
Tom 执行克隆操作并找到了一个新文件 string.c。他想了解是谁将此文件添加到仓库的以及出于什么目的，因此他执行了 git log 命令。
[tom@CentOS ~]$ git clone gituser@git.server.com:project.git以上命令将生成以下结果 −
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以上命令将生成以下结果 −
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在观察日志后，他意识到文件 string.c 是由 Jerry 添加的，以实现基本字符串操作。他对 Jerry 的代码感到好奇。因此，他在文本编辑器中打开了 string.c，并立即发现了错误。在 my_strlen 函数中，Jerry 没有使用常量指针。所以，他决定修改 Jerry 的代码。修改后，代码如下 −
[tom@CentOS project]$ git diff以上命令将生成以下结果 −
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;
}在测试后，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以上命令将生成以下结果 −
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 commitTom 使用 git push 命令去推送他的更改。
[tom@CentOS project]$ git push origin master以上命令将生成以下结果 −
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 −> masterAdd New Function
与此同时，Jerry 决定实现 string compare 功能。因此，他修改了 string.c。修改后，该文件如下所示 −
[jerry@CentOS project]$ git diff以上命令将生成以下结果 −
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，他准备推送自己的变更。
[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验证提交。
[jerry@CentOS project]$ git log以上命令将生成以下结果 −
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 commitJerry 对更改感到满意，他想推送他的更改。
[jerry@CentOS project]$ git push origin master以上命令将生成以下结果 −
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.但是，Git 不允许 Jerry 推送他的更改。因为 Git 识别出远程仓库和 Jerry 的本地仓库不同步。因此，他可能会丢失项目的历史记录。为了避免出现混乱，Git 失败了此操作。现在，Jerry 必须首先更新本地仓库，然后才能推送自己的更改。
Fetch Latest Changes
Jerry 执行 git pull 命令将他的本地仓库与远程仓库同步。
[jerry@CentOS project]$ git pull以上命令将生成以下结果 −
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在 pull 操作之后，Jerry 检查日志消息并查找 Tom 的提交的详细信息，提交 ID 为 cea2c000f53ba99508c5959e3e12fff493ba6f69
[jerry@CentOS project]$ git log以上命令将生成以下结果 −
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 的本地仓库已与远程仓库完全同步。因此，他可以安全地推送自己的更改。
[jerry@CentOS project]$ git push origin master以上命令将生成以下结果 −
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