--set-upstream 的作用， 基本上是 改变一个分支的 merge 头。 其他的不变。
D:\code\git\mw\me\umc-portal>git pull main2 dev
From http://192.169.2.234/umc/umc-portal
* branch dev -> FETCH_HEAD
Auto-merging utils/src/main/java/com/lk/umc/portal/util/file/UploadFileUtil.java
CONFLICT (content): Merge conflict in utils/src/main/java/com/lk/umc/portal/util/file/UploadFileUtil.java
Automatic merge failed; fix conflicts and then commit the result.
D:\code\git\mw\me\umc-portal>git pull main2 dev
error: You have not concluded your merge (MERGE_HEAD exists).
hint: Please, commit your changes before merging.
fatal: Exiting because of unfinished merge.
D:\code\git\mw\me\umc-portal>git pull main2 dev
From http://192.169.2.234/umc/umc-portal
* branch dev -> FETCH_HEAD
Already up to date.
D:\code\git\mw\me\umc-portal>git pull
Already up to date.
D:\code\git\mw\me\umc-portal>git pull main2
remote: Enumerating objects: 877, done.
remote: Counting objects: 100% (877/877), done.
remote: Compressing objects: 100% (288/288), done.
remote: Total 877 (delta 264), reused 767 (delta 232)
Receiving objects: 100% (877/877), 314.45 KiB | 2.07 MiB/s, done.
Resolving deltas: 100% (264/264), completed with 72 local objects.
From http://192.169.2.234/umc/umc-portal
0b0ec1e7..4ba2af93 dev -> main2/dev
97643ee7..db0057cd dev-aim2.0 -> main2/dev-aim2.0
* [new branch] revert-c42d09a5 -> main2/revert-c42d09a5
c42d09a5..16bb46d5 umc_portal_gw -> main2/umc_portal_gw
68c7df09..c1b7af18 管理服务-代码扫描漏洞修复 -> main2/管理服务-代码扫描漏洞修复
You asked to pull from the remote 'main2', but did not specify
a branch. Because this is not the default configured remote
for your current branch, you must specify a branch on the command line.
D:\code\git\mw\me\umc-portal>git remote -vv
main2 http://192.169.2.234/umc/umc-portal.git (fetch)
main2 http://192.169.2.234/umc/umc-portal.git (push)
origin http://192.169.2.234/lk/umc-portal.git (fetch)
origin http://192.169.2.234/lk/umc-portal.git (push)
remote 和 upstream 的区别
D:\code\git\mw\me\umc-portal>git pull main2
remote: Enumerating objects: 15, done.
remote: Counting objects: 100% (15/15), done.
remote: Compressing objects: 100% (9/9), done.
remote: Total 15 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (15/15), 17.30 KiB | 33.00 KiB/s, done.
From http://192.169.2.234/umc/umc-portal
d742db5c..cb57963c dev-aim2.0 -> main2/dev-aim2.0
You asked to pull from the remote 'main2', but did not specify
a branch. Because this is not the default configured remote
for your current branch, you must specify a branch on the command line.
D:\code\git\mw\me\umc-portal>git pull
There is no tracking information for the current branch.
Please specify which branch you want to merge with.
See git-pull(1) for details.
git pull <remote> <branch>
If you wish to set tracking information for this branch you can do so with:
git branch --set-upstream-to=<remote>/<branch> devlk
++++++++++
一。使用场景: 本地新建一个分支后，必须要做远程分支关联。如果没有关联，git会在下面的操作中提示你显示的添加关联。关联目的是如果在本地分支下操作： git pull, git push ，不需要指定在命令行指定远程的分支．
下面的方式 是行不通的！！
D:\code\git\mw\me\umc-portal>git pull main2 devlk
fatal: couldn't find remote ref devlk
D:\code\git\mw\me\umc-portal>git pull main2:dev devlk
ssh: Could not resolve hostname main2: Name or service not known
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.
看来只有 通过 --set-upstream-to=
upstream 其实是一个仓库名字，但是它是一个概念， 而 origin 这样的是 具体名字。当然， 我们也可以使用它作为名字，因为他不是关键字， 语法是：
git pull upstream master
D:\code\git\mw\me\umc-portal>git remote add upstream https://github.com/devopscube/vagrant-examples.git
error: remote upstream already exists.
D:\code\git\mw\me\umc-portal>git remote -vv
...
upstream https://github.com/devopscube/vagrant-examples.git (fetch)
upstream https://github.com/devopscube/vagrant-examples.git (push)
+++ 创建一个新的 远程分支
D:\code\git\mw\me\umc-portal>git push -u origin
fatal: The current branch devlk has no upstream branch.
To push the current branch and set the remote as upstream, use
git push --set-upstream origin devlk
D:\code\git\mw\me\umc-portal>git push -u origin devlk
Enumerating objects: 348, done.
Counting objects: 100% (281/281), done.
Delta compression using up to 16 threads
Compressing objects: 100% (62/62), done.
Writing objects: 100% (175/175), 68.62 KiB | 9.80 MiB/s, done.
Total 175 (delta 72), reused 138 (delta 45), pack-reused 0
remote: Resolving deltas: 100% (72/72), completed with 24 local objects.
remote:
remote: To create a merge request for devlk, visit:
remote: http://192.169.2.234/luokai/umc-portal/merge_requests/new?merge_request%5Bsource_branch%5D=devlk
remote:
To http://192.169.2.234/luokai/umc-portal.git
* [new branch] devlk -> devlk
Branch 'devlk' set up to track remote branch 'devlk' from 'origin'.
----
D:\code\git\mw\me\umc-portal>git pull --set-upstream origin dev3:dev2
From http://192.169.2.234/luokai/umc-portal
! [rejected] dev3 -> dev2 (non-fast-forward)
D:\code\git\mw\me\umc-portal>git pull --set-upstream origin dev4:dev2
fatal: couldn't find remote ref dev4
D:\code\git\mw\me\umc-portal>git pull --set-upstream origin HEAD:dev2
From http://192.169.2.234/luokai/umc-portal
! [rejected] -> dev2 (non-fast-forward)
为什么被拒绝？ 大概是因为 HEAD:dev2 不能被识别。。 可能是不需要指定 本地分支 HEAD , 只能当前分支上pull，
D:\code\git\mw\me\umc-portal>git pull --set-upstream origin dev2
From http://192.169.2.234/luokai/umc-portal
* branch dev2 -> FETCH_HEAD
Updating 912dabdd..d2cc7b50
Fast-forward
system/src/main/resources/readme.txt | 7 +++++++
1 file changed, 7 insertions(+)
create mode 100644 system/src/main/resources/readme.txt
D:\code\git\mw\me\umc-portal>git pull origin dev2
From http://192.169.2.234/luokai/umc-portal
* branch dev2 -> FETCH_HEAD
Already up to date.
D:\code\git\mw\me\umc-portal>git pull origin dev3
From http://192.169.2.234/luokai/umc-portal
* branch dev3 -> FETCH_HEAD
Already up to date.
---- 终于成功：
D:\code\git\mw\me\umc-portal>git pull --set-upstream origin dev3
From http://192.169.2.234/luokai/umc-portal
* branch dev3 -> FETCH_HEAD
Already up to date.
------ 观察 config文件：
[branch "dev2"]
remote = origin
merge = refs/heads/dev
[branch "dev4"]
remote = origin
merge = refs/heads/dev3
可见， git pull --set-upstream 的作用， 基本上是 改变一个分支的 merge 头。 其他的不变。
3个使用方式：
1 git branch --set-upstream xx
1 git pull --set-upstream xx
1 git push --set-upstream upstreamName localBranchName , 在远程 upstreamName 仓库创建一个名为localBranchName的分支
-u 就是 --set-upstream
