本篇文章来源于《GitHub入门与实践》第4章 通过实际操作学习Git
1、基本操作
初始化成功后该目录下会生成.git目录(也称为附属于该仓库的工作树 )，储存管理当前目录内容所需的仓库数据
文件的编辑等操作在工作树中进行，然后记录到仓库中，以此管理文件的历史快照。如果想将文件恢复到原先的状态，可以从仓库中调取之前的快照，在工作树中打开1 2 3 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test $ git init Initialized empty Git repository in C:/Users/G3/Desktop/git test/.git/
工作树和仓库在被操作的过程中，状态会不断发生变化1 2 3 4 5 6 7 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git status On branch master No commits yet nothing to commit (create/copy files and use "git add" to track)
所谓提交（Commit），是指“记录工作树中所有文件的当前状态”
新建README.md文件后的status如下：1 2 3 4 5 6 7 8 9 10 11 12 13 14 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ touch README.md G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git status On branch master No commits yet Untracked files: (use "git add <file>..." to include in what will be committed) README.md nothing added to commit but untracked files present (use "git add" to track)
只是用Git仓库的工作树创建了文件，那么该文件并不会被记入Git仓库的版本管理对象当中。因此我们用git status命令查看README.md文件时，它会显示在Untracked files里。
要想让文件成为Git仓库的管理对象，就需要用gitadd命令将其加入暂存区（Stage或者Index）中。暂存区是提交之前的一个临时区域
1 2 3 4 5 6 7 8 9 10 11 12 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git add README.md G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git status On branch master No commits yet Changes to be committed: (use "git rm --cached <file>..." to unstage) new file: README.md
该命令将当前暂存区中的文件实际保存到仓库的历史记录中。通过这些记录，我们就可以在工作树中复原文件
-m参数后的称为提交信息，是对该提交的概述
1 2 3 4 5 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git commit -m "First commit" [master (root-commit) 066eaf7] First commit 1 file changed, 0 insertions(+), 0 deletions(-) create mode 100644 README.md
记录详细提交信息
不加-m参数，直接执行git commit命令，接着会打开对应的编辑器编辑提交信息，其格式如下：
第一行：用一行文字简述提交的更改内容
第二行：空行
第三行以后：记述更改的原因和详细内容终止提交 查看提交后状态
1 2 3 4 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git status On branch master nothing to commit, working tree clean
查看以往仓库中提交的日志。包括可以查看什么人在什么时候进行了提交或合并，以及操作前后有怎样的差别注：若日志较长无法完全显示，可回车往下显示一行，并且按”q”正常退出，若非正常退出则会造成继续输入命令时无法正常显示出来；若出现这样的情况可以输入reset命令重置git bash，也可关闭当前终端重新打开 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git log commit 02117edd38575da4a4de7a40be083cef2e7883b2 (HEAD -> master) Author: Thee24LYJ <1579290423@qq.com> Date: Mon Feb 21 14:32:23 2022 +0800 file context changed. I am trying to change this context of the README.md file changed by LYJ commit 066eaf72002d80f78d7031f22e38db8c87f03a9e Author: Thee24LYJ <1579290423@qq.com> Date: Mon Feb 21 14:25:49 2022 +0800 First commit
只显示提交信息第一行
使用命令git log --pretty=short即可只显示指定目录、文件日志 git log filename即可
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 $ git log README.md commit 02117edd38575da4a4de7a40be083cef2e7883b2 (HEAD -> master) Author: Thee24LYJ <1579290423@qq.com> Date: Mon Feb 21 14:32:23 2022 +0800 file context changed. I am trying to change this context of the README.md file changed by LYJ commit 066eaf72002d80f78d7031f22e38db8c87f03a9e Author: Thee24LYJ <1579290423@qq.com> Date: Mon Feb 21 14:25:49 2022 +0800 First commit
显示文件改动
使用命令git log -p即可在提交信息后显示文件的前后差别1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 $ git log -p commit 02117edd38575da4a4de7a40be083cef2e7883b2 (HEAD -> master) Author: Thee24LYJ <1579290423@qq.com> Date: Mon Feb 21 14:32:23 2022 +0800 file context changed. I am trying to change this context of the README.md file changed by LYJ diff --git a/README.md b/README.md index e69de29..71b6fb7 100644 --- a/README.md +++ b/README.md @@ -0,0 +1,5 @@ +# hello world + +This is a test, I am trying to learn git and do some excise(maybe). + +And this is a test file. \ No newline at end of file
git diff命令可以查看工作树、暂存区、最新提交之间的差别
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 $ git diff diff --git a/README.md b/README.md index 71b6fb7..5b82da4 100644 --- a/README.md +++ b/README.md @@ -2,4 +2,6 @@ This is a test, I am trying to learn git and do some excise(maybe). -And this is a test file. \ No newline at end of file +The line be deleted. This is a description. + +And this is a new line. \ No newline at end of file
由于我们尚未用git add命令向暂存区添加任何东西，所以程序只会显示工作树与最新提交状态之间的差别
+”号标出的是新添加的行，被删除的行则用“-”号标出
使用git add README.md将README.md文件加入暂存区
查看工作树和最新提交的差别
现在执行git diffgit diff HEAD
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git diff G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git diff HEAD diff --git a/README.md b/README.md index 71b6fb7..5b82da4 100644 --- a/README.md +++ b/README.md @@ -2,4 +2,6 @@ This is a test, I am trying to learn git and do some excise(maybe). -And this is a test file. \ No newline at end of file +The line be deleted. This is a description. + +And this is a new line. \ No newline at end of file
不妨养成这样一个好习惯：在执行git commit命令之前先执行git diff HEAD命令，查看本次提交与上次提交之间有什么差别，等确认完毕后再进行提交。这里的HEAD是指向当前分支中最新一次提交的指针
1 2 3 $ git commit -m "Add something new and delete something old" [master a071997] Add something new and delete something old 1 file changed, 3 insertions(+), 1 deletion(-)
查看提交日志：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 $ git log commit a07199771e6436b72a32b6fec45b90caf4ed8c1b (HEAD -> master) Author: Thee24LYJ <1579290423@qq.com> Date: Mon Feb 21 14:51:20 2022 +0800 Add something new and delete something old commit 02117edd38575da4a4de7a40be083cef2e7883b2 Author: Thee24LYJ <1579290423@qq.com> Date: Mon Feb 21 14:32:23 2022 +0800 file context changed. I am trying to change this context of the README.md file changed by LYJ commit 066eaf72002d80f78d7031f22e38db8c87f03a9e Author: Thee24LYJ <1579290423@qq.com> Date: Mon Feb 21 14:25:49 2022 +0800 First commit
2、分支操作
1 2 3 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git branch * master
标 * 表示当前所在分支
git checkout —创建(添加参数-b)、切换分支
使用如下命令进行切换：
1 2 3 4 5 6 7 8 9 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git checkout -b feature-A Switched to a new branch 'feature-A' G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (feature-A) G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (feature-A) $ git branch * feature-A master
此时修改代码、执行git add命令提交，代码会提交到feature-A分支，像这样不断对一个分支（例如feature-A）进行提交的操作，我们称为“培育分支”
注：这里在feature-A修改代码并提交后再切换到master分支，代码不会有相应的改动
切换回上一个分支
用“-”（连字符）代替分支名，就可以切换至上一个分支。当然，将“-”替换成master同样可以切换到master分支1 2 3 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (feature-A) $ git checkout - Switched to branch 'master'
特性分支
特性分支顾名思义，是集中实现单一特性（主题），除此之外不进行任何作业的分支。在日常开发中，往往会创建数个特性分支，同时在此之外再保留一个随时可以发布软件的稳定分支。稳定分支的角色通常由master分支担当
主干分支
主干分支是刚才我们讲解的特性分支的原点，同时也是合并的终点。通常人们会用master分支作为主干分支
使用命令git merge --no-ff feature-A，参数—no-ff是为了在历史记录中明确记录下本次分支合并
1 2 3 4 5 6 7 8 9 10 11 12 13 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git merge --no-ff feature-A hint: Waiting for your editor to close the file... [main 2022-02-22T06:12:20.690Z] update#setState idle [main 2022-02-22T06:12:21.135Z] ExtensionHostStarterWorker created [main 2022-02-22T06:12:23.323Z] Starting extension host with pid 13468 (fork() took 103 ms). [main 2022-02-22T06:12:23.324Z] ExtensionHostStarterWorker.start() took 106 ms. [main 2022-02-22T06:12:50.696Z] update#setState checking for updates [main 2022-02-22T06:12:50.792Z] update#setState idle [main 2022-02-22T06:13:03.000Z] Extension host with pid 13468 exited with code: 0, signal: null. Merge made by the 'recursive' strategy. README.md | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
用git log —graph命令进行查看的话，能很清楚地看到特性分支（feature-A）提交的内容已被合并。除此以外，特性分支的创建以及合并也都清楚明了
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 git log --graph * commit 4c6d8896e9e288b21a36aa840f0c536d8154d683 (HEAD -> master) |\ Merge: a071997 40d98e7 | | Author: Thee24LYJ <1579290423@qq.com> | | Date: Tue Feb 22 14:12:18 2022 +0800 | | | | Merge branch 'feature-A' into master | | | * commit 40d98e76c16be3748c4cc78d178049b579450e13 (feature-A) |/ Author: Thee24LYJ <1579290423@qq.com> | Date: Tue Feb 22 14:01:11 2022 +0800 | | add to feature-A | * commit a07199771e6436b72a32b6fec45b90caf4ed8c1b | Author: Thee24LYJ <1579290423@qq.com> | Date: Mon Feb 21 14:51:20 2022 +0800 | | Add something new and delete something old | * commit 02117edd38575da4a4de7a40be083cef2e7883b2 | Author: Thee24LYJ <1579290423@qq.com> | Date: Mon Feb 21 14:32:23 2022 +0800 | | file context changed. | | I am trying to change this context of the README.md file | changed by LYJ | * commit 066eaf72002d80f78d7031f22e38db8c87f03a9e Author: Thee24LYJ <1579290423@qq.com> Date: Mon Feb 21 14:25:49 2022 +0800 First commit
3、更改提交操作
这里为熟悉对历史版本的操作，先回溯历史版本，创建一个名为fix-B的特性分支
1 2 3 4 5 6 7 8 9 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git checkout -b fix-B Switched to a new branch 'fix-B' G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (fix-B) $ git branch feature-A * fix-B master
回溯到创建feature-A分支前
要让仓库的HEAD、暂存区、当前工作树回溯到指定状态，需要用到gitreset —hard命令。只要提供目标时间点的哈希值[插图]，就可以完全恢复至该时间点的状态
1 2 3 4 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git reset --hard a07199771e6436b72a32b6fec45b90caf4ed8c1b HEAD is now at a071997 Add something new and delete something old
已经成功回溯到特性分支（feature-A）创建之前的状态。由于所有文件都回溯到了指定哈希值对应的时间点上，README.md文件的内容也恢复到了当时的状态创建fix-B分支
1 2 3 4 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git checkout -b fix-B Switched to a new branch 'fix-B'
修改代码内容并提交1 2 3 4 5 6 7 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (fix-B) $ git add README.md G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (fix-B) $ git commit -m "fix-B change" [fix-B e690648] fix-B change 1 file changed, 9 insertions(+), 1 deletion(-)
推进至feature-A分支合并后的状态
首先恢复到feature-A分支合并后的状态。不妨称这一操作为“推进历史”
git log命令只能查看以当前状态为终点的历史日志。所以这里要使用gitreflog命令，查看当前仓库的操作日志。在日志中找出回溯历史之前的哈希值，通过git reset —hard命令恢复到回溯历史前的状态
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (fix-B) $ git reflog e690648 (HEAD -> fix-B) HEAD@{0}: commit: fix-B change a071997 (master) HEAD@{1}: checkout: moving from master to fix-B a071997 (master) HEAD@{2}: reset: moving to a07199771e6436b72a32b6fec45b90caf4ed8c1b 4c6d889 HEAD@{3}: checkout: moving from fix-B to master 4c6d889 HEAD@{4}: checkout: moving from master to fix-B 4c6d889 HEAD@{5}: merge feature-A: Merge made by the 'recursive' strategy. a071997 (master) HEAD@{6}: checkout: moving from feature-A to master 40d98e7 (feature-A) HEAD@{7}: checkout: moving from master to feature-A a071997 (master) HEAD@{8}: checkout: moving from master to master a071997 (master) HEAD@{9}: checkout: moving from feature-A to master 40d98e7 (feature-A) HEAD@{10}: checkout: moving from master to feature-A a071997 (master) HEAD@{11}: checkout: moving from feature-A to master 40d98e7 (feature-A) HEAD@{12}: commit: add to feature-A a071997 (master) HEAD@{13}: checkout: moving from master to feature-A a071997 (master) HEAD@{14}: checkout: moving from feature-A to master a071997 (master) HEAD@{15}: checkout: moving from master to feature-A a071997 (master) HEAD@{16}: commit: Add something new and delete something old 02117ed HEAD@{17}: commit: file context changed. 066eaf7 HEAD@{18}: commit (initial): First commit
在日志中，我们可以看到commit、checkout、reset、merge等Git命令的执行记录。只要不进行Git的GC（Garbage Collection，垃圾回收），就可以通过日志随意调取近期的历史状态，就像给时间机器指定一个时间点，在过去未来中自由穿梭一般。即便开发者错误执行了Git操作，基本也都可以利用git reflog命令恢复到原先的状态
恢复到回溯前的历史状态1 2 3 4 5 6 7 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (fix-B) $ git checkout master Switched to branch 'master' G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git reset --hard 4c6d889 HEAD is now at 4c6d889 Merge branch 'feature-A' into master
消除冲突
现在只要合并fix-B分支，就可以得到我们想要的状态
1 2 3 4 5 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git merge --no-ff fix-B Auto-merging README.md CONFLICT (content): Merge conflict in README.md Automatic merge failed; fix conflicts and then commit the result.
系统告诉我们README.md文件发生了冲突（Conflict）。系统在合并README.md文件时，feature-A分支更改的部分与本次想要合并的fix-B分支更改的部分发生了冲突。不解决冲突就无法完成合并，所以我们打开README.md文件解决这个冲突
提交解决后结果
1 2 3 4 5 6 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master|MERGING) $ git add README.md G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master|MERGING) $ git commit -m "Fix conflict by LYJ" [master 898df01] Fix conflict by LYJ
要修改上一条提交信息，可以使用git commit —amend命令。我们将上一条提交信息记为了”Fix conflict”，但它其实是fix-B分支的合并，解决合并时发生的冲突只是过程之一，这样标记实在不妥。于是，我们要修改这条提交信息
执行上述命令后再打开的编辑器中修改之前提交信息，之后保存文件并关闭编辑器
如果只是想修改上一次提交的代码内容，可以先修改代码文件，然后使用以下命令：
1 2 git add <file> git commit --amend
其中<file>为要修改的文件名。这样就可以修改上一次提交的代码内容了。需要注意的是，如果已经将修改推送到远程仓库，不建议修改历史提交记录，以免引起其他人的代码混乱。
执行git log —graph命令，可以看到提交日志中的相应内容也已经被修改
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 $ git log --graph * commit a783495d5c1328df81c759b2c2521cae175d4ae6 (HEAD -> master) |\ Merge: 4c6d889 e690648 | | Author: Thee24LYJ <1579290423@qq.com> | | Date: Tue Feb 22 14:41:40 2022 +0800 | | | | Merge branch 'fix-B' | | | * commit e6906488cc59494f376a0673f65d0da0dd260c97 (fix-B) | | Author: Thee24LYJ <1579290423@qq.com> | | Date: Tue Feb 22 14:32:16 2022 +0800 | | | | fix-B change | | * | commit 4c6d8896e9e288b21a36aa840f0c536d8154d683 |\ \ Merge: a071997 40d98e7 | |/ Author: Thee24LYJ <1579290423@qq.com> |/| Date: Tue Feb 22 14:12:18 2022 +0800 | | | | Merge branch 'feature-A' into master | | | * commit 40d98e76c16be3748c4cc78d178049b579450e13 (feature-A) |/ Author: Thee24LYJ <1579290423@qq.com> | Date: Tue Feb 22 14:01:11 2022 +0800 | | add to feature-A | * commit a07199771e6436b72a32b6fec45b90caf4ed8c1b | Author: Thee24LYJ <1579290423@qq.com> | Date: Mon Feb 21 14:51:20 2022 +0800 | | Add something new and delete something old | * commit 02117edd38575da4a4de7a40be083cef2e7883b2 | Author: Thee24LYJ <1579290423@qq.com> | Date: Mon Feb 21 14:32:23 2022 +0800 | | file context changed. | | I am trying to change this context of the README.md file | changed by LYJ | * commit 066eaf72002d80f78d7031f22e38db8c87f03a9e Author: Thee24LYJ <1579290423@qq.com> Date: Mon Feb 21 14:25:49 2022 +0800 First commit
git rebase -i 压缩历史
在合并特性分支之前，如果发现已提交的内容中有些许拼写错误等，不妨提交一个修改，然后将这个修改包含到前一个提交之中，压缩成一个历史记录
1 2 3 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (master) $ git checkout -b feature-C Switched to a new branch 'feature-C'
作为feature-C的功能实现，我们在README.md文件中添加一行文字，并且故意留下拼写错误，以便之后修正.
1 2 3 $ git commit -am "add feature-C" [feature-C a6c2906] add feature-C 1 file changed, 3 insertions(+)
1 2 3 4 5 6 7 8 9 10 11 12 $ git diff diff --git a/README.md b/README.md index e49ccca..8b79141 100644 --- a/README.md +++ b/README.md @@ -17,4 +17,4 @@ hello world...! --- -- faeture-C +- feature-C
然后提交
1 2 3 4 G3@DESKTOP-OM3KFRO MINGW64 ~/Desktop/git test (feature-C) $ git commit -am "Fix typo" [feature-C 508e161] Fix typo 1 file changed, 1 insertion(+), 1 deletion(-)
错字漏字等失误称作typo，所以我们将提交信息记为”Fix typo”。实际上，我们不希望在历史记录中看到这类提交，因为健全的历史记录并不需要它们
将”Fix typo”修正的内容与之前一次的提交合并，在历史记录中合并为一次完美的提交
用上述方式执行git rebase命令，可以选定当前分支中包含HEAD（最新提交）在内的两个最新历史记录为对象，并在编辑器中打开
1 2 3 4 5 pickup a6c2906 add feature-C pickup 508e161 Fix typo ---修改 pickup a6c2906 add feature-C fixup 508e161 Fix typo
1 2 3 4 5 6 7 8 9 10 $ git rebase -i HEAD~2 hint: Waiting for your editor to close the file... [main 2022-02-22T06:53:27.400Z] update#setState idle [main 2022-02-22T06:53:27.436Z] ExtensionHostStarterWorker created [main 2022-02-22T06:53:28.558Z] Starting extension host with pid 12816 (fork() took 51 ms). [main 2022-02-22T06:53:28.558Z] ExtensionHostStarterWorker.start() took 51 ms. [main 2022-02-22T06:53:57.413Z] update#setState checking for updates [main 2022-02-22T06:53:57.507Z] update#setState idle [main 2022-02-22T06:54:12.586Z] Extension host with pid 12816 exited with code: 0, signal: null. Successfully rebased and updated refs/heads/feature-C.
此时再查看日志会发现add feature-C的哈希值改变了，这样一来，Fix typo就从历史中被抹去，也就相当于Add feature-C中从来没有出现过拼写错误。这算是一种良性的历史改写
4.修改上一次提交的内容
执行上述命令后，会打开编辑器，并显示上一次提交时的提交信息。在编辑器中修改提交信息后保存并退出即可。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 $ git checkout master Switched to branch 'master' $ git merge --no-ff feature-C hint: Waiting for your editor to close the file... [main 2022-02-22T06:59:46.546Z] update#setState idle [main 2022-02-22T06:59:46.575Z] ExtensionHostStarterWorker created [main 2022-02-22T06:59:47.640Z] Starting extension host with pid 15528 (fork() took 54 ms). [main 2022-02-22T06:59:47.640Z] ExtensionHostStarterWorker.start() took 55 ms. [main 2022-02-22T07:00:00.585Z] Waiting for extension host with pid 15528 to exit. [main 2022-02-22T07:00:00.585Z] Extension host with pid 15528 exited with code: 0, signal: null. Merge made by the 'recursive' strategy. README.md | 3 +++ 1 file changed, 3 insertions(+)
4、推送至远程仓库
前面三个部分都是针对本地单一仓库的操作，现在开始接触网络上的远程仓库
1.git remote add —添加远程仓库
1 git remote add origin git@github.com:用户名/git-tutorial.git
2.git push —推送至远程仓库
1 2 git push -u origin master
像这样执行git push命令，当前分支的内容就会被推送给远程仓库origin的master分支。-u参数可以在推送的同时，将origin仓库的master分支设置为本地仓库当前分支的upstream（上游）。添加了这个参数，将来运行git pull命令从远程仓库获取内容时，本地仓库的这个分支就可以直接从origin的master分支获取内容，省去了另外添加参数的麻烦
执行该操作后，当前本地仓库master分支的内容将会被推送到GitHub的远程仓库中
1 git push -u origin feature-D
5、从远程仓库获取 1.git clone —获取远程仓库
1 git clone git@github.com:用户名/git-tutorial.git
执行git clone命令后我们会默认处于master分支下，同时系统会自动将origin设置成该远程仓库的标识符。也就是说，当前本地仓库的master分支与GitHub端远程仓库（origin）的master分支在内容上是完全相同的
用git branch -a命令查看当前分支的相关信息。添加 -a参数可以同时显示本地仓库和远程仓库的分支信息
1 git checkout -b feature-D origin/feature-D
-b参数的后面是本地仓库中新建分支的名称。为了便于理解，我们仍将其命名为feature-D，让它与远程仓库的对应分支保持同名。新建分支名称后面是获取来源的分支名称。例子中指定了origin/feature-D，就是说以名为origin的仓库（这里指GitHub端的仓库）的feature-D分支为来源，在本地仓库中创建feature-D分支
这里跟之前的一样
从远程仓库获取feature-D分支，在本地仓库中提交更改，再将feature-D分支推送回远程仓库，通过这一系列操作，就可以与其他开发者相互合作，共同培育feature-D分支，实现某些功能
2.git pull —获取最新的远程仓库 使用git pull命令，将本地的feature-D分支更新到最新状态。当前分支为feature-D分支
1 git pull origin feature-D
