git详解2:分支与合并

一.分支

1.分支的简介

  在进行提交操作时,Git 会保存一个提交对象(commit object),

2.分支的创建

  创建一个 testing 分支, 你需要使用 git branch 命令:

$ git branch testing

3.分支的切换

$ git checkout testing

  再提交一次:

$ vim test.rb
$ git commit -a -m 'made a change'

  首先,我们创建dev分支,然后切换到dev分支:

$ git checkout -b dev
Switched to a new branch 'dev'

  git checkout命令加上-b参数表示创建并切换,相当于以下两条命令:

$ git branch dev
$ git checkout dev
Switched to branch 'dev'

  用git branch命令查看当前分支:

$ git branch
* dev
  master

  git branch命令会列出所有分支,当前分支前面会标一个*号。

  对readme.txt做个修改,加上一行:

Creating a new branch is quick.

4.分支的删除

  使用带 -d选项的 git branch 命令来删除分支:

$ git branch -d hotfix
Deleted branch hotfix (3a0874c).

5.分支的合并

  检出到你想合并入的分支,然后运行 git merge 命令:

$ git checkout master
Switched to branch 'master'
$ git merge iss53
Merge made by the 'recursive' strategy.
index.html |    1 +
1 file changed, 1 insertion(+)

遇到冲突时的分支合并 

  有时候合并操作不会如此顺利。 如果你在两个不同的分支中,对同一个文件的同一个部分进行了不同的修改,Git 就没法干净的合并它们。 如果你对 #53 问题的修改和有关 hotfix 的修改都涉及到同一个文件的同一处,在合并它们的时候就会产生合并冲突:

$ git merge iss53
Auto-merging index.html
CONFLICT (content): Merge conflict in index.html
Automatic merge failed; fix conflicts and then commit the result.

  此时 Git 做了合并,但是没有自动地创建一个新的合并提交。 Git 会暂停下来,等待你去解决合并产生的冲突。 你可以在合并冲突后的任意时刻使用 git status 命令来查看那些因包含合并冲突而处于未合并(unmerged)状态的文件:

$ git status
On branch master
You have unmerged paths.
  (fix conflicts and run "git commit")

Unmerged paths:
  (use "git add <file>..." to mark resolution)

    both modified:      index.html

no changes added to commit (use "git add" and/or "git commit -a")

  任何因包含合并冲突而有待解决的文件,都会以未合并状态标识出来。 Git 会在有冲突的文件中加入标准的冲突解决标记,这样你可以打开这些包含冲突的文件然后手动解决冲突。 出现冲突的文件会包含一些特殊区段,看起来像下面这个样子:

<<<<<<< HEAD:index.html
<div id="footer">contact : email.support@github.com</div>
=======
<div id="footer">
 please contact us at support@github.com
</div>
>>>>>>> iss53:index.html

  这表示 HEAD 所指示的版本(也就是你的 master 分支所在的位置,因为你在运行 merge 命令的时候已经检出到了这个分支)在这个区段的上半部分(======= 的上半部分),而 iss53 分支所指示的版本在 ======= 的下半部分。 为了解决冲突,你必须选择使用由 ======= 分割的两部分中的一个,或者你也可以自行合并这些内容。 例如,你可以通过把这段内容换成下面的样子来解决冲突:

<div id="footer">
please contact us at email.support@github.com
</div>

  上述的冲突解决方案仅保留了其中一个分支的修改,并且 &lt;&lt;&lt;&lt;&lt;&lt;&lt; , ======= , 和 &gt;&gt;&gt;&gt;&gt;&gt;&gt; 这些行被完全删除了。 在你解决了所有文件里的冲突之后,对每个文件使用 git add 命令来将其标记为冲突已解决。 一旦暂存这些原本有冲突的文件,Git 就会将它们标记为冲突已解决。

6.分支管理

$ git branch
  iss53
* master
  testing

  master 分支前的 * 字符:它代表现在检出的那一个分支

Bug分支

  有了bug就需要修复,在Git中,由于分支是如此的强大,所以,每个bug都可以通过一个新的临时分支来修复,修复后,合并分支,然后将临时分支删除。

  Git还提供了一个stash功能,可以把当前工作现场“储藏”起来,等以后恢复现场后继续工作:

$ git stash
Saved working directory and index state WIP on dev: f52c633 add merge

  首先确定要在哪个分支上修复bug,假定需要在master分支上修复,就从master创建临时分支:

$ git checkout master
Switched to branch 'master'
Your branch is ahead of 'origin/master' by 6 commits.
  (use "git push" to publish your local commits)

$ git checkout -b issue-101
Switched to a new branch 'issue-101'

  现在修复bug,需要把“Git is free software ...”改为“Git is a free software ...”,然后提交:

$ git add readme.txt 
$ git commit -m "fix bug 101"
[issue-101 4c805e2] fix bug 101
 1 file changed, 1 insertion(+), 1 deletion(-)

  修复完成后,切换到master分支,并完成合并,最后删除issue-101分支:

$ git checkout master
Switched to branch 'master'
Your branch is ahead of 'origin/master' by 6 commits.
  (use "git push" to publish your local commits)

$ git merge --no-ff -m "merged bug fix 101" issue-101
Merge made by the 'recursive' strategy.
 readme.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

  现在,是时候接着回到dev分支

$ git checkout dev
Switched to branch 'dev'

$ git status
On branch dev
nothing to commit, working tree clean

  工作区是干净的,刚才的工作现场存到哪去了?用git stash list命令看看:

$ git stash list
stash@{0}: WIP on dev: f52c633 add merge

  工作现场还在,Git把stash内容存在某个地方了,但是需要恢复一下,有两个办法:

一是用git stash apply恢复,但是恢复后,stash内容并不删除,你需要用git stash drop来删除;

  另一种方式是用git stash pop,恢复的同时把stash内容也删了:

$ git stash pop
On branch dev
Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

    new file:   hello.py

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:   readme.txt

Dropped refs/stash@{0} (5d677e2ee266f39ea296182fb2354265b91b3b2a)

  再用git stash list查看,就看不到任何stash内容了:

$ git stash list

  你可以多次stash,恢复的时候,先用git stash list查看,然后恢复指定的stash,用命令:

$ git stash apply stash@{0}

7.dev 分支

  准备开发:

$ git checkout -b dev-vulcan
Switched to a new branch 'dev-vulcan'

  5分钟后,开发完毕:

$ git add vulcan.py

$ git status
On branch dev-vulcan
Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

    new file:   vulcan.py

$ git commit -m "add feature vulcan"
[feature-vulcan 287773e] add feature vulcan
 1 file changed, 2 insertions(+)
 create mode 100644 vulcan.py

  切回dev,准备合并:

$ git checkout dev

销毁

$ git branch -d  dev-vulcan
error: The branch 'dev-vulcan' is not fully merged.
If you are sure you want to delete it, run 'git branch -D dev-vulcan'.

  销毁失败。Git友情提醒,dev-vulcan分支还没有被合并,如果删除,将丢失掉修改,如果要强行删除,需要使用大写的-D参数。

$ git branch -D dev-vulcan
Deleted branch dev-vulcan (was 287773e).

 参考:https://blog.51cto.com/wangfeng7399/2352662

 

二.多人协作

  克隆仓库的命令格式是git clone [url]

$ git clone https://github.com/libgit2/libgit2

   自定义本地仓库的名字,你可以使用如下命令:

$ git clone https://github.com/libgit2/libgit2 mylibgit

  发生冲突时:先pull,在本地合并,然后才能push成功。合并后,分支变成了下面:

$ git log --graph --pretty=oneline --abbrev-commit
* d1be385 (HEAD -> master, origin/master) init hello
*   e5e69f1 Merge branch 'dev'
|\  
| *   57c53ab (origin/dev, dev) fix env conflict
| |\  
| | * 7a5e5dd add env
| * | 7bd91f1 add new env
| |/  
* |   12a631b merged bug fix 101
|\ \  
| * | 4c805e2 fix bug 101
|/ /  
* |   e1e9c68 merge with no-ff
|\ \  
| |/  
| * f52c633 add merge
|/  
*   cf810e4 conflict fixed

  Git有一种称为rebase的操作,有人把它翻译成“变基”

  在和远程分支同步后,我们对hello.py这个文件做了两次提交。用git log命令看看:

$ git log --graph --pretty=oneline --abbrev-commit
* 582d922 (HEAD -> master) add author
* 8875536 add comment
* d1be385 (origin/master) init hello
*   e5e69f1 Merge branch 'dev'
|\  
| *   57c53ab (origin/dev, dev) fix env conflict
| |\  
| | * 7a5e5dd add env
| * | 7bd91f1 add new env
...

  推送本地分支:

$ git push origin master
To github.com:michaelliao/learngit.git
 ! [rejected]        master -> master (fetch first)
error: failed to push some refs to 'git@github.com:michaelliao/learngit.git'
hint: Updates were rejected because the remote contains work that you do
hint: not have locally. This is usually caused by another repository pushing
hint: to the same ref. You may want to first integrate the remote changes
hint: (e.g., 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

这样就失败了,这说明有人先于我们推送了远程分支。按照经验,先pull一下:

$ git pull
remote: Counting objects: 3, done.
remote: Compressing objects: 100% (1/1), done.
remote: Total 3 (delta 1), reused 3 (delta 1), pack-reused 0
Unpacking objects: 100% (3/3), done.
From github.com:michaelliao/learngit
   d1be385..f005ed4  master     -> origin/master
 * [new tag]         v1.0       -> v1.0
Auto-merging hello.py
Merge made by the 'recursive' strategy.
 hello.py | 1 +
 1 file changed, 1 insertion(+)

  再用git status看看状态:

$ git status
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 tree clean

  用git log看看:

$ git log --graph --pretty=oneline --abbrev-commit
*   e0ea545 (HEAD -> master) Merge branch 'master' of github.com:michaelliao/learngit
|\  
| * f005ed4 (origin/master) set exit=1
* | 582d922 add author
* | 8875536 add comment
|/  
* d1be385 init hello
...

现在把本地分支push到远程,有没有问题?有,不好看

  输入命令git rebase试试:

$ git rebase
First, rewinding head to replay your work on top of it...
Applying: add comment
Using index info to reconstruct a base tree...
M    hello.py
Falling back to patching base and 3-way merge...
Auto-merging hello.py
Applying: add author
Using index info to reconstruct a base tree...
M    hello.py
Falling back to patching base and 3-way merge...
Auto-merging hello.py

  再用git log看看:

$ git log --graph --pretty=oneline --abbrev-commit
* 7e61ed4 (HEAD -> master) add author
* 3611cfe add comment
* f005ed4 (origin/master) set exit=1
* d1be385 init hello
...

  最后,通过push操作把本地分支推送到远程:

Mac:~/learngit michael$ git push origin master
Counting objects: 6, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (5/5), done.
Writing objects: 100% (6/6), 576 bytes | 576.00 KiB/s, done.
Total 6 (delta 2), reused 0 (delta 0)
remote: Resolving deltas: 100% (2/2), completed with 1 local object.
To github.com:michaelliao/learngit.git
   f005ed4..7e61ed4  master -> master

  再用git log看看效果:

$ git log --graph --pretty=oneline --abbrev-commit
* 7e61ed4 (HEAD -> master, origin/master) add author
* 3611cfe add comment
* f005ed4 set exit=1
* d1be385 init hello
...

远程分支

1.推送

$ git push origin serverfix
Counting objects: 24, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (15/15), done.
Writing objects: 100% (24/24), 1.91 KiB | 0 bytes/s, done.
Total 24 (delta 2), reused 0 (delta 0)
To https://github.com/schacon/simplegit
 * [new branch]      serverfix -> serverfix

抓取数据时

$ git fetch origin
remote: Counting objects: 7, done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 3 (delta 0), reused 3 (delta 0)
Unpacking objects: 100% (3/3), done.
From https://github.com/schacon/simplegit
 * [new branch]      serverfix    -> origin/serverfix

如果想要在自己的 serverfix分支上工作,可以将其建立在远程跟踪分支之上:

$ git checkout -b serverfix origin/serverfix
Branch serverfix set up to track remote branch serverfix from origin.
Switched to a new branch 'serverfix'

2.跟踪分支

$ git checkout --track origin/serverfix
Branch serverfix set up to track remote branch serverfix from origin.
Switched to a new branch 'serverfix'

  如果想要将本地分支与远程分支设置为不同名字,你可以轻松地增加一个不同名字的本地分支的上一个命令:

$ git checkout -b sf origin/serverfix
Branch sf set up to track remote branch serverfix from origin.
Switched to a new branch 'sf'

  设置已有的本地分支跟踪一个刚刚拉取下来的远程分支,或者想要修改正在跟踪的上游分支,你可以在任意时间使用 -u 或 --set-upstream-to 选项运行 git branch 来显式地设置。

$ git branch -u origin/serverfix
Branch serverfix set up to track remote branch serverfix from origin.

  如果想要查看设置的所有跟踪分支,可以使用 git branch 的 -vv 选项

$ git branch -vv
  iss53     7e424c3 [origin/iss53: ahead 2] forgot the brackets
  master    1ae2a45 [origin/master] deploying index fix
* serverfix f8674d9 [teamone/server-fix-good: ahead 3, behind 1] this should do it
  testing   5ea463a trying something new

3.删除远程分支

$ git push origin --delete serverfix
To https://github.com/schacon/simplegit
 - [deleted]         serverfix

参考:https://blog.51cto.com/wangfeng7399/2352667

 

三.忽略特殊文件

1.忽略特殊文件的原则:

  1. 忽略操作系统自动生成的文件,比如缩略图等;
  2. 忽略编译生成的中间文件、可执行文件等,也就是如果一个文件是通过另一个文件自动生成的,那自动生成的文件就没必要放进版本库,比如Java编译产生的.class文件;
  3. 忽略你自己的带有敏感信息的配置文件,比如存放口令的配置文件。

 有些时候,你想添加一个文件到Git,但发现添加不了,原因是这个文件被.gitignore忽略了:

$ git add App.class
The following paths are ignored by one of your .gitignore files:
App.class
Use -f if you really want to add them.

  确实想添加该文件,可以用-f强制添加到Git:

$ git add -f App.class

  可以用git check-ignore命令检查:

$ git check-ignore -v App.class
.gitignore:3:*.class    App.class

  .gitignore的第3行规则忽略了该文件,于是我们就可以知道应该修订哪个规则。

    忽略某些文件时,需要编写.gitignore

    .gitignore文件本身要放到版本库里,并且可以对.gitignore做版本管理!

 

四.标签的管理

1.列出标签

$ git tag
v0.1
v1.3

  如果只对 1.8.5 系列感兴趣,可以运行:

$ git tag -l 'v1.8.5*'
v1.8.5
v1.8.5-rc0
v1.8.5-rc1
v1.8.5-rc2
v1.8.5-rc3
v1.8.5.1
v1.8.5.2
v1.8.5.3
v1.8.5.4
v1.8.5.5

2.创建标签

  轻量标签(lightweight)与附注标签(annotated)

  2.1 附注标签       附注标签是存储在 Git 数据库中的一个完整对象

$ git tag -a v1.4 -m 'my version 1.4'
$ git tag
v0.1
v1.3
v1.4

  -m 选项指定了一条将会存储在标签中的信息

  通过使用 git show 命令可以看到标签信息与对应的提交信息:

$ git show v1.4
tag v1.4
Tagger: Ben Straub <ben@straub.cc>
Date:   Sat May 3 20:19:12 2014 -0700

my version 1.4

commit ca82a6dff817ec66f44342007202690a93763949
Author: Scott Chacon <schacon@gee-mail.com>
Date:   Mon Mar 17 21:52:11 2008 -0700

    changed the version number

  2.2  轻量标签       轻量标签本质上是将提交校验和存储到一个文件中 - 没有保存任何其他信息

$ git tag v1.4-lw
$ git tag
v0.1
v1.3
v1.4
v1.4-lw
v1.5

  如果在标签上运行 git show,你不会看到额外的标签信息。 命令只会显示出提交信息:

$ git show v1.4-lw
commit ca82a6dff817ec66f44342007202690a93763949
Author: Scott Chacon <schacon@gee-mail.com>
Date:   Mon Mar 17 21:52:11 2008 -0700

    changed the version number

3.后期打标签

$ git log --pretty=oneline
15027957951b64cf874c3557a0f3547bd83b3ff6 Merge branch 'experiment'
a6b4c97498bd301d84096da251c98a07c7723e65 beginning write support
0d52aaab4479697da7686c15f77a3d64d9165190 one more thing
6d52a271eda8725415634dd79daabbc4d9b6008e Merge branch 'experiment'
0b7434d86859cc7b8c3d5e1dddfed66ff742fcbc added a commit function
4682c3261057305bdd616e23b64b0857d832627b added a todo file
166ae0c4d3f420721acbb115cc33848dfcc2121a started write support
9fceb02d0ae598e95dc970b74767f19372d61af8 updated rakefile
964f16d36dfccde844893cac5b347e7b3d44abbc commit the todo
8a5cbc430f1a9c3d00faaeffd07798508422908a updated readme

  假设在 v1.2 时你忘记给项目打标签,也就是在 “updated rakefile” 提交。 你可以在之后补上标签。 要在那个提交上打标签,你需要在命令的末尾指定提交的校验和(或部分校验和):

$ git tag -a v1.2 9fceb02

4.共享标签

$ git push origin v1.5
Counting objects: 14, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (12/12), done.
Writing objects: 100% (14/14), 2.05 KiB | 0 bytes/s, done.
Total 14 (delta 3), reused 0 (delta 0)
To git@github.com:schacon/simplegit.git
 * [new tag]         v1.5 -> v1.5

  如果想要一次性推送很多标签,也可以使用带有 --tags 选项的 git push 命令

$ git push origin --tags
Counting objects: 1, done.
Writing objects: 100% (1/1), 160 bytes | 0 bytes/s, done.
Total 1 (delta 0), reused 0 (delta 0)
To git@github.com:schacon/simplegit.git
 * [new tag]         v1.4 -> v1.4
 * [new tag]         v1.4-lw -> v1.4-lw

5.删除标签

  要删除掉你本地仓库上的标签,可以使用命令 git tag -d &lt;tagname&gt;

  可以使用下面的命令删除掉一个轻量级标签:

$ git tag -d v1.4-lw
Deleted tag 'v1.4-lw' (was e7d5add)

  应该注意的是上述命令并不会从任何远程仓库中移除这个标签,你必须使用 git push &lt;remote&gt; :refs/tags/&lt;tagname&gt; 来更新你的远程仓库:

$ git push origin :refs/tags/v1.4-lw
To /git@github.com:schacon/simplegit.git
 - [deleted]         v1.4-lw

6. 检出标签

  如果你想查看某个标签所指向的文件版本,可以使用 git checkout 命令

posted @ 2020-07-16 11:26  会打架的程序员不是好客服  阅读(980)  评论(0编辑  收藏  举报