本篇文章已授权微信公众号 guolin_blog （郭霖）独家发布
0. 序言
之前不太重视Git的命令行操作，直到去了前些天一直炒的非常火的某某某某公司，呆了几天帮忙解BUG，发现项目不用AndroidStudio的图形化界面操作版本控制，一时间傻眼......想到应该也有小伙伴和我一样，所以就有了这篇文章，希望通过阅读这篇文章大家都能学会Git命令行操作。
讲述方式非面面俱到。喜欢后者的，可以买本书细细品。讲解目录如下：
- 简介
- Git的完整性
- Git的文件状态和工作区域
- 用户身份
- 编辑器
- 创建本地仓库
- 常用本地操作
- 版本回退
- 撤销修改
- 删除相关操作
- 远程仓库
- 分支
- 解决冲突
- 变基
1. 简介
Git 是分布式版本控制系统，客户端保留完整的代码仓库，就算搭载远程仓库的服务器出了故障，客户端的数据也可以用来恢复服务器数据。
Git 操作几乎都在本地完成，速度快，效率高，且不受网络限制。
2. Git的完整性
Git以校验和的方式检测数据的完整性。采用的校验和机制叫做SHA-1散列。SHA-1散列由40个十六进制字符（0-9和a-f）所组成的字符串，这些字符串是根据文件内容和Git的目录结构计算所得。在Git中commit id 就是校验和，如下：
$git log
commit 555af4a0aadb6c64a73acfd94c8fe89af5604083
Author: Fu Kaiqiang <fukaiqiang@xxx.com>
Date: Mon Sep 17 10:45:24 2018 +0800
first commit
3. Git的文件状态和工作区域
- 工作区域：
① 工作目录：平时写代码的区域。
② 暂存区：代码add以后commit之前所在的地方。
③ 本地仓库：代码commit以后所在的地方。 - 文件状态：
① 已修改：工作目录修改以后，代码没有add到暂存区，也没有commit到本地仓库。
② 已暂存：工作目录修改以后，代码已经add到暂存区，没有commit到本地仓库。
③ 已提交：工作目录修改以后，代码已经commit到本地仓库。
3. 用户身份
- 配置个人信息
$ git config --global user.name "Your Name"
$ git config --global user.email "email@example.com"
说明：--global 表示你这台机器上所有的Git仓库都会使用这个配置
- 查看个人信息
$git config --list
user.email=fukaiqiang@xxx.com
user.name=Fu Kaiqiang
alias.st=status
alias.co=checkout
alias.dt=difftool -t meld -y
color.ui=auto
core.repositoryformatversion=0
core.filemode=true
core.bare=false
core.logallrefupdates=true
remote.origin.url=git@github.com:OnlyYouMyLove/TestGit.git
remote.origin.fetch=+refs/heads/*:refs/remotes/origin/*
branch.master.remote=origin
branch.master.merge=refs/heads/master
4. 编辑器
- 不同操作系统推荐使用不同编辑器，Linux推荐使用Vim，Window可使用NotePad++
以vim为例:
vim TestGit.md
说明：vim 可以创建并打开TestGit.md文件。不是重点，不详述，感兴趣，可找小度或小谷。
5. 创建本地仓库
- 初始化本地仓库
- $ git init
说明：初始化仓库，生成 .git 文件即可
- 克隆远程仓库到本地
$git clone git@github.com:OnlyYouMyLove/TestGit.git
Cloning into 'TestGit'...
remote: Counting objects: 6, done.
remote: Compressing objects: 100% (4/4), done.
remote: Total 6 (delta 0), reused 6 (delta 0), pack-reused 0
Receiving objects: 100% (6/6), 4.76 KiB | 0 bytes/s, done.
Checking connectivity... done.
说明：
① 初始化仓库和克隆远程仓库是创建本地仓库两种方式，根据场景不同，选择不同的创建方式。
② 本地仓库初始化以后，还需要和远程仓库进行关联，远程仓库部分讲。
6. 常用本地操作
- 添加文件到暂存区
$ git add readme.txt
- 把暂存区的文件提交到本地仓库
$ git commit -m "wrote a readme file"
说明： -m后添加此次提交的说明
- 跳过暂存区执行提交
$git commit -a -m "skip stage to commit"
On branch master
Your branch is ahead of 'origin/master' by 3 commits.
(use "git push" to publish your local commits)
nothing to commit, working directory clean
说明：-a 参数可以自动暂存文件，然后执行提交。
- 查看本地仓库提交历史
$git log
commit 462a66ec484df873bc5638fbd53523408ecfed43
Merge: 34a6e3f 44d733a
Author: Fu Kaiqiang <fukaiqiang@xxx.com>
Date: Fri Sep 14 10:28:10 2018 +0800
Merge remote-tracking branch 'origin/master'
commit 34a6e3f6dba34d4870da3f9a25ab653a33ae2a49
Author: Fu Kaiqiang <fukaiqiang@xxx.com>
Date: Fri Sep 14 10:21:42 2018 +0800
Today is Friday!
- 简洁的方式查看本地仓库提交历史
$git log --pretty=oneline
462a66ec484df873bc5638fbd53523408ecfed43 Merge remote-tracking branch 'origin/master'
34a6e3f6dba34d4870da3f9a25ab653a33ae2a49 Today is Friday!
- 查看文件状态
$git status
On branch master
Your branch is up-to-date with 'origin/master'.
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: TestGit.md
Untracked files:
(use "git add <file>..." to include in what will be committed)
.TestGit.md.swo
.TestGit.md.swp
说明：
① Changes to be committed：已暂存、可提交文件
② Untracked files：未暂存文件
- 查看未暂存文件变更细节
$git diff
diff --git a/TestGit.md b/TestGit.md
index 1de64fb..89aaf06 100644
--- a/TestGit.md
+++ b/TestGit.md
@@ -1,2 +1,3 @@
Hello World
Hello Chuizi
+Hello Branch
- 查看已暂存文件变更细节
$git diff --staged
diff --git a/TestGit.md b/TestGit.md
index bc8bff8..2d675a0 100644
--- a/TestGit.md
+++ b/TestGit.md
@@ -2,3 +2,4 @@ Hello World
Hello Chuizi
Hello HUAWEI
Hello XIAOMI
+Hello MEIZU
说明：文件一旦暂存，通过git diff命令就不能查询差异，必须添加--staged参数，或--cached参数。
7. 版本回退
- 回退到上一个版本
文件内容：
1 Hello World
2 Test Git
3 Hello ChuiZi
4 Hello JianGuo
5 hahahahah
6 fdafafafafaf
7 fajfkajfakdjfk
8 eight line
9 nine line
10 tenth line
$git log
commit c836aafa9e33890aebd9b53c816e3180ccd4ddb7
Author: Fu Kaiqiang <fukaiqiang@smartisan.com>
Date: Fri Sep 14 17:01:59 2018 +0800
add tenth line
commit b1a66343568506fdb9960ebd3d896fd798ac61a4
Author: Fu Kaiqiang <fukaiqiang@smartisan.com>
Date: Fri Sep 14 17:01:09 2018 +0800
add ninth line
$git reset --hard HEAD^
HEAD is now at b1a6634 add ninth line
说明：以上这句命令行代码是核心代码
$git log
commit b1a66343568506fdb9960ebd3d896fd798ac61a4
Author: Fu Kaiqiang <fukaiqiang@smartisan.com>
Date: Fri Sep 14 17:01:09 2018 +0800
add ninth line
文件内容：
1 Hello World
2 Test Git
3 Hello ChuiZi
4 Hello JianGuo
5 hahahahah
6 fdafafafafaf
7 fajfkajfakdjfk
8 eight line
9 nine line
- 查询每次版本提交记录
$git reflog
c836aaf HEAD@{0}: reset: moving to c836a
b1a6634 HEAD@{1}: reset: moving to HEAD^
c836aaf HEAD@{2}: commit: add tenth line
b1a6634 HEAD@{3}: commit: add ninth line
说明：内容包括 ① commit id ② 执行的命令 ③ 描述
- 回退到指定版本
$git reset --hard c836a
HEAD is now at c836aaf add tenth line
说明：
① 找到commit id，就可以回退到指定版本。
② commit id 不用填全部，填写部分，git 自动查找。
- 查看工作区和版本库里面最新版本的区别
修改TestGit.md内容为：
Hello World
$git add TestGit.md
再修改TestGit.md内容为：
Hello World
Hello Chuizi
$git commit -m "Two line"
[master 7dd7cf8] Two line
1 file changed, 1 insertion(+), 11 deletions(-)
$git status
On branch master
Your branch is ahead of 'origin/master' by 1 commit.
(use "git push" to publish your local commits)
Changes not staged for commit:
(use "git add <file>..." to update what will be committed)
(use "git checkout -- <file>..." to discard changes in working directory)
modified: TestGit.md
no changes added to commit (use "git add" and/or "git commit -a")
说明：这时发现还有未添加到暂存区的内容。
$git diff HEAD -- TestGit.md
diff --git a/TestGit.md b/TestGit.md
index 35eab83..1de64fb 100644
--- a/TestGit.md
+++ b/TestGit.md
@@ -1,2 +1,2 @@
Hello World
-
+Hello Chuizi
说明：
① 发现第二次修改没有提交到暂存区，导致 git commit 提交的只是第一次的修改。
② git diff 命令是核心代码。
③ 这个时候再执行一遍add和commit操作即可。
8. 撤销修改
- 撤销未添加到暂存区的修改
fukqdembp:TestGit fukq$ git status
On branch master
Your branch is up to date with 'origin/master'.
Changes not staged for commit:
(use "git add <file>..." to update what will be committed)
(use "git checkout -- <file>..." to discard changes in working directory)
modified: TestGit.md
no changes added to commit (use "git add" and/or "git commit -a")
说明：discard changes - 放弃修改:的提示为 "git checkout -- <file>..."
fukqdembp:TestGit fukq$ git checkout -- TestGit.md
fukqdembp:TestGit fukq$ git status
On branch master
Your branch is up to date with 'origin/master'.
nothing to commit, working tree clean
- 撤销已添加到暂存区的修改：
fukqdembp:TestGit fukq$ git add TestGit.md
fukqdembp:TestGit fukq$ git status
On branch master
Your branch is up to date with 'origin/master'.
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: TestGit.md
说明：to unstage - 不暂存的提示为 "git reset HEAD <file>..."
fukqdembp:TestGit fukq$ git reset HEAD TestGit.md
Unstaged changes after reset:
M TestGit.md
fukqdembp:TestGit fukq$ git status
On branch master
Your branch is up to date with 'origin/master'.
Changes not staged for commit:
(use "git add <file>..." to update what will be committed)
(use "git checkout -- <file>..." to discard changes in working directory)
modified: TestGit.md
no changes added to commit (use "git add" and/or "git commit -a")
fukqdembp:TestGit fukq$
9. 删除相关操作
- 删除文件后的Git同步操作
fukqdembp:TestGit fukq$ ls
LICENSE README.md TestGit.md TestGit.txt
fukqdembp:TestGit fukq$ rm TestGit.txt
fukqdembp:TestGit fukq$ git status
On branch master
Your branch is ahead of 'origin/master' by 1 commit.
(use "git push" to publish your local commits)
Changes not staged for commit:
(use "git add/rm <file>..." to update what will be committed)
(use "git checkout -- <file>..." to discard changes in working directory)
deleted: TestGit.txt
no changes added to commit (use "git add" and/or "git commit -a")
fukqdembp:TestGit fukq$ git rm TestGit.txt
rm 'TestGit.txt'
fukqdembp:TestGit fukq$ git commit TestGit.txt -m "删除TestGit.txt文件"
[master 7075b5f] 删除TestGit.txt文件
1 file changed, 1 deletion(-)
delete mode 100644 TestGit.txt
fukqdembp:TestGit fukq$ git status
On branch master
Your branch is ahead of 'origin/master' by 2 commits.
(use "git push" to publish your local commits)
nothing to commit, working tree clean
fukqdembp:TestGit fukq$ ls
LICENSE README.md TestGit.md
说明：
① rm TestGit.txt
② git rm TestGit.txt
③ git commit TestGit.txt -m "删除TestGit.txt文件"
- 删除文件后的恢复文件操作
fukqdembp:TestGit fukq$ rm TestGit.txt
fukqdembp:TestGit fukq$ git status
On branch master
Your branch is ahead of 'origin/master' by 3 commits.
(use "git push" to publish your local commits)
Changes not staged for commit:
(use "git add/rm <file>..." to update what will be committed)
(use "git checkout -- <file>..." to discard changes in working directory)
deleted: TestGit.txt
no changes added to commit (use "git add" and/or "git commit -a")
fukqdembp:TestGit fukq$ git checkout -- TestGit.txt
fukqdembp:TestGit fukq$ ls
LICENSE README.md TestGit.md TestGit.txt
说明：$ git checkout --TestGit.txt 既可以对未添加到暂存区的修改操作进行恢复，也可以对已删除的文件进行恢复。
10. 远程仓库
- 关联远程仓库
$git remote add origin git@github.com:OnlyYouMyLove/TestGit.git
说明：
① 组成 -- git remote add + 自定义仓库命名 + 仓库ssh地址
② git init 初始化仓库以后需要进行 git remote操作，实现本地和远程仓库的绑定，这才能算是完整创建本地仓库。
- 第一次推送本地仓库内容到远程仓库
$git push -u origin master
说明：
① -u 参数的添加可以让本地仓库和远程仓库进行绑定
② 如果报以下错,意思是缺少权限--本地生成ssh,添加到github的ssh列表即可：
$git push -u origin master
Warning: Permanently added the RSA host key for IP address 'xxx.xx.xxx.xxx' to the list of known hosts.
Permission denied (publickey).
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.
③ 如果报以下错,输入yes即可：
The authenticity of host 'github.com (xx.xx.xx.xx)' can't be established.
RSA key fingerprint is xx.xx.xx.xx.xx.
Are you sure you want to continue connecting (yes/no)?
Warning: Permanently added 'github.com' (RSA) to the list of known hosts.
说明：警告只会出现一次。
④ 查看ssh key (linux系统下，其他系统大同小异）:
$cat ~/.ssh/id_rsa.pub
- 非第一次推送本地仓库内容到远程仓库
$git push origin master
- 从远程仓库拉取数据到本地
$git fetch origin
说明：
① git clone 自动命名远程仓库服务器名字为origin，并拉取全部数据，然后在本地创建指向服务器上master分支的指针，并命名为origin/master,它就叫远程分支，接着git会创建本地master分支。
② fetch 这条命令会从服务器取得所有本地尚未包含的数据，然后更新远程分支。注意：只是更新远程分支，本地master分支并未改变，需要合并才行。
③ origin 与 master分支名称一样，只是默认名称，没有什么特殊含义，都可以自定义。
$git merge origin/master
Updating ce50a7f..253d867
Fast-forward
TestGit.md | 1 +
1 file changed, 1 insertion(+)
说明：只要经过fetch和merge才能把远程仓库的数据同步给本地仓库。
- 从远程仓库拉取数据并直接合并到本地
$git pull origin master
From github.com:OnlyYouMyLove/TestGit
* branch master -> FETCH_HEAD
Updating ce50a7f..5ec3b49
Fast-forward
.test.swp | Bin 0 -> 4096 bytes
TestGit.md | 3 +++
2 files changed, 3 insertions(+)
create mode 100644 .test.swp
说明：pull 命令直接拉取数据到远程分支并且合并数据到master分支。
11. 分支
- 创建并切换分支
$git checkout -b dev
Switched to a new branch 'dev'
说明：-b 参数 意思是 创建并切换分支，相当于下面两条命令
$ git branch dev 创建分支
$ git checkout dev 切换分支
Switched to branch 'dev'
- 查看当前分支
$git branch
* master
$git checkout -b dev
Switched to a new branch 'dev'
$git status
On branch dev
nothing to commit, working directory clean
$git branch
* dev
master
说明：核心命令--git branch，并用 * 指向当前所在分支
- 合并分支
$git branch
* dev
master
$vim TestGit.md
$git checkout master
M TestGit.md
Switched to branch 'master'
Your branch is up-to-date with 'origin/master'.
$git branch
dev
* master
$git merge dev
Already up-to-date.
说明：操作步骤如下
① 在dev分支上编辑TestGit
② 切换到master分支
③ 合并dev到当前分支master
- 删除分支
$git branch -d dev
Deleted branch dev (was 555af4a).
12. 解决冲突
- 场景分析和解决办法
一个文件，两个分支，每个分支都对文件中的相同一句话做了不同的修改。当一个分支修改完提交后，另外一个分支修改提交，然后合并另外一个分支的时候就会产生冲突，而解决的方法就是继续修改文件，把两个分支都操作的那句话进行最终编辑，然后提交即可。
创建并切换到dev分支
$git checkout -b dev
M TestGit.md
Switched to a new branch 'dev'
编辑TestGit.md文件
$vim TestGit.md
编辑以后：
Hello World
Hello Chuizi
Hello XIAOMI
暂存
$git add TestGit.md
提交
$git commit TestGit.md -m "dev commit file"
[dev 6a31928] dev commit file
1 file changed, 1 insertion(+)
切换到master分支
$git checkout master
Switched to branch 'master'
Your branch is up-to-date with 'origin/master'.
编辑TestGit.md文件
$vim TestGit.md
编辑以后：
Hello World
Hello Chuizi
Hello HUAWEI
暂存
$git add TestGit.md
提交
$git commit TestGit.md -m "master commit file"
[master b62ed88] master commit file
1 file changed, 1 insertion(+)
合并
$git merge dev
Auto-merging TestGit.md
CONFLICT (content): Merge conflict in TestGit.md
Automatic merge failed; fix conflicts and then commit the result.
编辑TestGit.md文件
$vim TestGit.md
Hello World
Hello Chuizi
<<<<<<< HEAD
Hello HUAWEI
=======
Hello XIAOMI
>>>>>>> dev
说明：=======上面是HEAD（master)版本 >>>>>>>上面是dev版本
解决冲突--进行编辑：
Hello World
Hello Chuizi
Hello HUAWEI
Hello XIAOMI
暂存
$git add TestGit.md
提交
$git commit TestGit.md
fatal: cannot do a partial commit during a merge.
说明：出现冲突以后，修改文件解决冲突后，不能提交部分文件
上面的commit修改为提交所有文件即可
$git commit -m "merge files"
[master 39791ca] merge files
- 查看分支的合并图：
$git log --graph --pretty=oneline --abbrev-commit
* 39791ca merge files
|\
| * 6a31928 dev commit file
* | b62ed88 master commit file
|/
* 555af4a first commit
从合并图可以看出来是dev和master的合并：
① 555af4a first commit ：首次的提交
② 6a31928 dev commit file b62ed88 master commit file ：dev先提交master后提交
③ 39791ca merge files ：解决冲突后合并提交
13. 变基
$git log --graph --pretty=oneline --abbrev-commit
* 39791ca merge files
|\
| * 6a31928 dev commit file
* | b62ed88 master commit file
|/
* 555af4a first commit
- 上面是分支冲突后的合并图log，你会发现非常混乱，两个commit一个merge，并不在一条直线上。而这仅仅是一次冲突的合并。合并越多，历史log越乱！一个项目的合并次数可能达到成百上千，如果历史合并log非常混乱，会对阅读造成非常大的障碍，影响工作效率，那能否左边的图是一条直线而非菱形呢？答案是肯定的，当本地出现冲突的时候使用变基--rebase来替代合并--merge。
- 那为什么merge后会产生菱形历史？这就要从其实质说起 : dev 分支、master 分支、两者的共同祖先一起合并生成新的快照，我们称这种提交叫做“合并提交"，而合并提交并非只有一个父提交，这里有两个dev和master。所以合并历史图出现了菱形。
复现冲突场景：dev和master分别修改了同一个文件的相同地方，并且执行了暂存和提交，然后我们这里执行rebase操作：
$git checkout dev
Switched to branch 'dev'
$git rebase master
First, rewinding head to replay your work on top of it...
Applying: dev commit
Using index info to reconstruct a base tree...
M TestGit.md
Falling back to patching base and 3-way merge...
Auto-merging TestGit.md
CONFLICT (content): Merge conflict in TestGit.md
error: Failed to merge in the changes.
Patch failed at 0001 dev commit
The copy of the patch that failed is found in: .git/rebase-apply/patch
When you have resolved this problem, run "git rebase --continue".
If you prefer to skip this patch, run "git rebase --skip" instead.
To check out the original branch and stop rebasing, run "git rebase --abort".
说明：rebase失败，让先解决冲突，然后用 "git rebase --continue"
$vim TestGit.md
$git add TestGit.md
$git rebase --continue
Applying: dev commit
$git checkout master
Switched to branch 'master'
Your branch is ahead of 'origin/master' by 1 commit.
(use "git push" to publish your local commits)
$git merge dev
Updating 6321248..ce50a7f
Fast-forward
TestGit.md | 1 +
1 file changed, 1 insertion(+)
$git log --graph --pretty=oneline --abbrev-commit
* ce50a7f dev commit
* 6321248 master commit
* 555af4a first commit
- 为什么变基可以实现一条线的历史提交效果呢？那我们也看看其原理：首先找到两个要整合的分支（你当前所在的分支和要整合到的分支）的共同祖先，然后取得当前所在分支的每次提交引入的更改（diff），并把这些更改保存为临时文件，这之后将当前分支重置为要整合到的分支，最后在该分支上依次引入之前保存的每个更改。说白了就是记录dev的更改并保存，然后把保存的更改依次引入master分支，这样相当于所有的更改都在master上。merge和rebase的结果相同，但是提交历史完全不同。
- 你说还不明白，还是没有看出区别！但是你仔细想想其实区别很大：变基实际上是抛弃了dev的已有的提交，随后创建了新的对应提交，内容相似，但是却是不同的提交。
14. 后续
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