Git 回到未来
Wed, 25 May 2016 13:02:46 +0000
git rebase
修改 commit 的顺序、内容，修改历史。
$ git rebase -i HEAD~5
pick 3d60303 Update content ponctuation$
pick 17aa86b Add copywriter style and update about.$
pick 27729ba Update style guide$
pick 3f90bbf Update css and about$
pick 86a43d2 add draft$
$
# Rebase b2811ee..86a43d2 onto b2811ee (5 command(s))$
#$
# Commands:$
# p, pick = use commit$
# r, reword = use commit, but edit the commit message$
# e, edit = use commit, but stop for amending$
# s, squash = use commit, but meld into previous commit$
# f, fixup = like "squash", but discard this commit's log message$
# x, exec = run command (the rest of the line) using shell$
# d, drop = remove commit$
#$
# These lines can be re-ordered; they are executed from top to bottom.$
#$
# If you remove a line here THAT COMMIT WILL BE LOST.$
#$
22 # However, if you remove everything, the rebase will be aborted.$
#$
# Note that empty commits are commented out$
$ git rebase -i <commit> 这个命令就是列出到指定 commit 的所有 commit，然后我们可以对这些 commit 进行操作，比如说删掉某几个 commit、合并某几个、调换某几个 commit 的顺序。
原本我们的 git flow 是：
$ git log --oneline --graph --decorate --all
* ed4c919 add draft
* f105e3d Merge pull request #11 from lincolnge/release
|\
| * 3f90bbf Update css and about
|/
* 27729ba Update style guide
* 17aa86b Add copywriter style and update about.
* 3d60303 Update content ponctuation
执行 $ git rebase -i HEAD~5，没有进行任何操作，就退出，执行 $ git log --oneline --graph --decorate --all 可以看到，现在我们的 git flow 是：
* f423ed9 (HEAD -> test) add draft
| * 79bdd26 (origin/master, origin/HEAD, master) add post git back to the future
| * ed4c919 add draft
| * f105e3d Merge pull request #11 from lincolnge/release
| |\
| |/
|/|
* | 3f90bbf Update css and about
|/
* 27729ba Update style guide
* 17aa86b Add copywriter style and update about.
* 3d60303 Update content ponctuation
我们可以认为 git rebase 操作把我们的 commit 给捋平了。就是当前 branch 的分支变成这样了。（$ git log --oneline --graph --decorate，去掉远程的 git flow，可以看得更清晰一些。）
* f423ed9 (HEAD -> test) add draft
* 3f90bbf Update css and about
* 27729ba Update style guide
* 17aa86b Add copywriter style and update about.
* 3d60303 Update content ponctuation
原本那个 merge 操作产生的 commit 被删掉了。
这里可以插一段，解决冲突。当我们发完 PR 的时候，产生冲突了，这个时候要在本地解决这个冲突，我们可以使用 git rebase 或 git merge 去解决冲突，区别就是 git merge 会多产生一个 commit，然后使用 git rebase 会更改你这个 PR 里 所有 commit 的 hash 值。然后当你发现你解决冲突的时所做的操作有问题时，git merge 更容易进行回溯的操作，直接 git reset 即可。
# Commands:$
# p, pick = use commit$
# r, reword = use commit, but edit the commit message$
# e, edit = use commit, but stop for amending$
# s, squash = use commit, but meld into previous commit$
# f, fixup = like "squash", but discard this commit's log message$
# x, exec = run command (the rest of the line) using shell$
# d, drop = remove commit$
看看我们的 rebase -i 里面的有的操作。默认都是 pick。
pick 3d60303 Update content ponctuation$
pick 17aa86b Add copywriter style and update about.$
pick 27729ba Update style guide$
pick 3f90bbf Update css and about$
pick 86a43d2 add draft$
比如把第二个 pick 改成 r，
pick 3d60303 Update content ponctuation$
r 17aa86b Add copywriter style and update about.$
pick 27729ba Update style guide$
pick 3f90bbf Update css and about$
pick 86a43d2 add draft$
保存并退出，发现我们到了 Add copywriter style and update about. 这个状态的时间点。我们可以对这个 commit 的 comment 进行操作，更改这个 commit comment。
NORMAL ▶▶ .git/rebase-merge/git-rebase-todo[+] ◀ gitrebase ◀ utf-8[unix] ◀ 8% ¶ 2: 2 ◀
".git/rebase-merge/git-rebase-todo" 24L, 842C [w]
Rebasing (2/5)
Add copywriter style and update about, change cimmit comment.$
$
# Please enter the commit message for your changes. Lines starting$
# with '#' will be ignored, and an empty message aborts the commit.$
#$
# Author: lincolnge <326684793@qq.com>$
# Date: Sat May 21 22:06:21 2016 +0800$
#$
# interactive rebase in progress; onto b2811ee$
# Last commands done (2 commands done):$
# pick 3d60303 Update content ponctuation$
# r e18bd53 Add copywriter style and update about, change cimmit comment.$
# Next commands to do (3 remaining commands):$
# pick e256546 Update style guide$
# pick 69c9c89 Update css and about$
# You are currently editing a commit while rebasing branch 'test' on 'b2811ee'.$
#$
# Changes to be committed:$
#»——————new file: _posts/2016-05-21-copywriting-style-guid.md$
#»——————modified: about.md$
#$
对 commit comment 修改并保存，保存完后，发现我们又重新回到了现在。重新执行 $ git log --oneline --graph --decorate，我们会看到我们的 commit comment 变了：
* 5c952ba (HEAD -> test) add draft
* 0a8c12c Update css and about
* 2dc468e Update style guide
* 8f265f0 Add copywriter style and update about, change cimmit comment.
* 3d60303 Update content ponctuation
这就是我们对过去进行了矫正，然后影响了我们的未来。
# r, reword = use commit, but edit the commit message$
# e, edit = use commit, but stop for amending$
# s, squash = use commit, but meld into previous commit$
# f, fixup = like "squash", but discard this commit's log message$
# x, exec = run command (the rest of the line) using shell$
# d, drop = remove commit$
看一下我们剩下的还有什么命令，edit、squash、fixup、exec、drop。顾名思义，edit 就是回到我们过去的那个时间点，然后对当时的 commit 进行修改，你可以直接在那个 commit 时间下添加新的 commit 或者你做你想做的任何一件事，结束后就执行 git rebase --continue 回到未来。
在 edit 状态下，我们同样可以执行 git rebase --edit-todo 看未来的 commit 或者对未来的 commit 执行类似 edit、squash、fixup、exec、drop 操作。
- squash 就是把指定的 commit 与它之前的 commit 合并，比如说你写了很多 fix bug、fix bug 的 commit，可以用这个 squash 统一变成一个 commit。
- fixup 与 squash 类似，但是它放弃了自己的部分权利，就是修改 commit comment 的信息。直接就合到它之前的 commit 了。
- drop 放弃这个 commit
- exec 也是一个很有趣的命令，它能让你到某个过去，然后执行指定的命令。
如下：
pick 3d60303 Update content ponctuation$
exec npm run test
pick 17aa86b Add copywriter style and update about.$
exec npm run test
pick 27729ba Update style guide$
exec npm run test
pick 3f90bbf Update css and about$
exec npm run test
pick 86a43d2 add draft$
友情提示，我们在解决冲突的时候有个命令叫 $ git rebase --skip，可以认为是去掉冲突的代码，也就是和遵从 git rebase
git cherry-pick
这个命令相对于 git rebase 来说，简单得多了，它就是把某个 commit 提取出来，放置到当前 branch 的 HEAD 上。
$ git cherry-pick 27729ba 17aa86b 3d60303 b2811ee f891ff0 7d3e6ae 7256dc9 30cb9d5 d9c90e4
[test 1de481e] Update style guide
Author: lincolnge <326684793@qq.com>
Date: Sat May 21 22:07:37 2016 +0800
1 file changed, 4 insertions(+)
[test a5b1c9b] Add copywriter style and update about.
Author: lincolnge <326684793@qq.com>
Date: Sat May 21 22:06:21 2016 +0800
2 files changed, 23 insertions(+), 2 deletions(-)
create mode 100644 _posts/2016-05-21-copywriting-style-guid.md
error: could not apply 3d60303... Update content ponctuation
hint: after resolving the conflicts, mark the corrected paths
hint: with 'git add <paths>' or 'git rm <paths>'
hint: and commit the result with 'git commit'
遇到冲突（conflict），
hint: after resolving the conflicts, mark the corrected paths
hint: with 'git add <paths>' or 'git rm <paths>'
hint: and commit the result with 'git commit'
这三句就是冲突的意思了。解决一下冲突，然后执行 $ git cherry-pick --continue，不像 git rebase，git cherry-pick 没有 –skip 方法。和 rebase 一样可以执行 git cherry-pick --abort 终止命令。
拓展与 git rebase & git merge 的联合使用。
我们可以测试一下当我们 cherry-pick 某个分支的某个 commit 之后，重新去合对应的分支，是否会产生冲突。
$ git co -b test2
$ git log --oneline --graph --decorate
* ed4c919 (HEAD -> test, master) add draft
* f105e3d Merge pull request #11 from lincolnge/release
|\
| * 3f90bbf Update css and about
|/
* 27729ba Update style guide
* 17aa86b Add copywriter style and update about.
* 3d60303 Update content ponctuation
看到我们的树状结构是这样的。
$ git reset --hard HEAD~3
HEAD is now at 17aa86b Add copywriter style and update about.
$ git log --oneline --graph --decorate
* 17aa86b (HEAD -> test) Add copywriter style and update about.
* 3d60303 Update content ponctuation
* b2811ee Update post content
* f891ff0 Update post title
* 7d3e6ae Update post title
$ git cherry-pick ed4c919
[test eeadbc2] add draft
Author: wanggengzhou <326684793@qq.com>
Date: Sat Oct 3 15:01:24 2015 0800
3 files changed, 978 insertions()
create mode 100644 _posts/2015-06-09-web.md
create mode 100644 _posts/reading/2015-06-24-the-art-of-speak.md
create mode 100644 _posts/reading/2015-08-23-tan-xiu-yang.md
$ git log --oneline --graph --decorate
* eeadbc2 (HEAD -> test) add draft
| * ed4c919 (master) add draft
| * f105e3d Merge pull request #11 from lincolnge/release
| |\
| | * 3f90bbf Update css and about
| |/
| * 27729ba Update style guide
|/
* 17aa86b Add copywriter style and update about.
* 3d60303 Update content ponctuation
看到我们这个时候的状态，我们可以选择 git merge 或 git rebase master 分支。
$ git co -b test2
checkout 一个新的分支，test 用来执行 git rebase，test2 用来执行 git merge。
$ git merge master
* 395d3bd (HEAD -> test2) Merge branch 'master' into test2
|\
| * ed4c919 (master) add draft
| * f105e3d Merge pull request #11 from lincolnge/release
| |\
| | * 3f90bbf Update css and about
| |/
| * 27729ba Update style guide
* | eeadbc2 (test) add draft
|/
* 17aa86b Add copywriter style and update about.
$ git rebase master
* ed4c919 (HEAD -> test, master) add draft
* f105e3d Merge pull request #11 from lincolnge/release
|\
| * 3f90bbf Update css and about
|/
* 27729ba Update style guide
* 17aa86b Add copywriter style and update about.
* 3d60303 Update content ponctuation
* b2811ee Update post content
我们可以发现执行完 rebase 得到的结果，与 master 的结果是一样的。结论：rebase 是个神奇的命令。使用 cherry-pick 不会产生的冲突。
git filter-branch
git filter-branch 这个命令非常强大，可以批量改写历史，当前 branch 中所有的 commit 的历史或者所有分支，可以选择适用的范围。
批量删除指定的 filename 文件：
$ git filter-branch --tree-filter 'rm -f filename' -- --all
例如：
$ git filter-branch --tree-filter 'rm -f test' -- --all
Cannot rewrite branches: You have unstaged changes.
当然不能有修改，可以先执行 $ git stash 命令。
$ git filter-branch --tree-filter 'rm -f test' -- --all
Cannot create a new backup.
A previous backup already exists in refs/original/
Force overwriting the backup with -f
出现这一句说明之前曾经执行过 git filter-branch，然后在 refs/original/ 有一个备份，这个时候只要删掉那个备份即可，删除备份命令为 git update-ref -d refs/original/refs/heads/master，或执行 $ git filter-branch -f --tree-filter -f 'rm -f test' -- --all。
为了避免因操作错误造 repo 损坏，git 会在 filter-branch 操作实际改写历史时，自动将原 refs 备份到 refs/original/ 下。
$ git filter-branch -f --tree-filter 'rm -f test' -- --all
Rewrite 283f0899973f574fd879f565b69da2705dc3ede7 (406/412) (24 seconds passed, remaining 0 predicted)
WARNING: Ref 'refs/heads/master' is unchanged
WARNING: Ref 'refs/heads/release' is unchanged
Ref 'refs/heads/test' was rewritten
Ref 'refs/heads/test2' was rewritten
Ref 'refs/heads/test3' was rewritten
Ref 'refs/heads/test4' was rewritten
Ref 'refs/heads/test5' was rewritten
Ref 'refs/heads/test6' was rewritten
WARNING: Ref 'refs/remotes/origin/master' is unchanged
WARNING: Ref 'refs/remotes/origin/master' is unchanged
WARNING: Ref 'refs/remotes/origin/release' is unchanged
WARNING: Ref 'refs/stash' is unchanged
看看改了什么 $ git status：
$ git st
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 directory clean
看看 .git/refs/original/ 里有啥：
$ l .git/refs/original/refs/heads/
total 24K
drwxr-xr-x 8 wanggengzhou staff 272 May 30 00:12 ./
drwxr-xr-x 3 wanggengzhou staff 102 May 30 00:09 ../
-rw-r--r-- 1 wanggengzhou staff 41 May 30 00:11 test
-rw-r--r-- 1 wanggengzhou staff 41 May 30 00:11 test2
-rw-r--r-- 1 wanggengzhou staff 41 May 30 00:11 test3
-rw-r--r-- 1 wanggengzhou staff 41 May 30 00:11 test4
-rw-r--r-- 1 wanggengzhou staff 41 May 30 00:12 test5
-rw-r--r-- 1 wanggengzhou staff 41 May 30 00:12 test6
$ cat .git/refs/original/refs/heads/test
a1029f5cce896f6d65dfbc5edfcf3487459aad3b
refs/original/ 里保存的就是 hash 值。其他命令介绍。
更改历史提交中某一提交者的姓名及邮件地址。
$ git filter-branch --commit-filter '
if [ "$GIT_AUTHOR_NAME" = "WangGengZhou" ]; then
GIT_AUTHOR_NAME="lincolnge"
GIT_AUTHOR_EMAIL="326684793@qq.com"
fi
git commit-tree "$@";
' HEAD
Reference:
- Git Documentation. https://git-scm.com/docs/git-rebase
- Git Documentation. https://git-scm.com/docs/git-cherry-pick
- Git Documentation. https://git-scm.com/docs/git-filter-branch
- GotGit. http://www.worldhello.net/gotgit/06-migrate/050-git-to-git.html
- loveky的一亩三分地. http://loveky2012.blogspot.com/2012/08/git-command-git-filter-branch.html
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