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实际开发过程中，我们经常会遇到这样的问题，当我们想把远程仓库的最新代码拉下来时，发现git会提示说我们本地做的修改会被覆盖，建议先commit代码或者stash（暂存）代码。你一定遇到过类似下面这样的提示：
$ git pull origin master
remote: Counting objects: 4, done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 4 (delta 1), reused 3 (delta 1), pack-reused 0
Unpacking objects: 100% (4/4), done.
From github.com:flysqrlboy/git-command-tutorials
* branch master -> FETCH_HEAD
7dd2e09..d7e1e19 master -> origin/master
Updating 7dd2e09..d7e1e19
error: Your local changes to the following files would be overwritten by merge:
b.txt
Please commit your changes or stash them before you merge.
Aborting
留意下面两句提示，我们可以有两个选择：commit或stash。
如果我们本地的代码修改得差不多了，可以选择commit到本地版本库。但如果我们的修改只是个半成品，我们不想把这样的代码留在提交历史里的话。git stash就能派上用场了。
git stash 暂存进度先来看下当前的工作区和暂存区状态：
$ git status
On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: a.txt
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: b.txt
git status 输出中告诉我们，a.txt 和 b.txt 都有修改，a.txt 已加入到暂存区（在Changes to be committed下面），b.txt 的修改则还在工作区中（在Changes not staged for commit下面）。正是因为远程代码库有人更改了b.txt ，才导致本地拉取代码时提示会被覆盖。这里，用git stash 命令保存当前工作进度。
$ git stashSaved working directory and index state WIP on master: 7dd2e09 add two files a.txt b.txt
运行git stash 之后，再查看工作区状态，会发现之前工作区和暂存区的修改都不见了。
$ git statusOn branch masternothing to commit, working tree clean
查看进度[color=#0990 !important]查看stash进度用命令git stash list
[color=#0990 !important]$ git stash liststash@{0}: WIP on master: 7dd2e09 add two files a.txt b.txt
[color=#0990 !important]可以看到刚刚暂存的进度有个标识 stash@{0}。如果想查看某个进度具体修改的文件可以用命令git stash show
[color=#0990 !important]$ git stash show stash@{0} a.txt | 1 + b.txt | 1 + 2 files changed, 2 insertions(+)
[color=#0990 !important]
恢复进度[color=#06666 !important]使用 git stash pop 从最近保存的进度进行恢复。
$ git stash pop
On branch 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: a.txt
modified: b.txt
no changes added to commit (use "git add" and/or "git commit -a")
Dropped refs/stash@{0} (ddc97ea74d33f3417f5ddab429a1dfeb3c08ca19)
通过git status查看工作区状态，可以看到之前的修改又回来了。
$ git status
On branch 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: a.txt
modified: b.txt
no changes added to commit (use "git add" and/or "git commit -a")
不过可能你也发现了一个小瑕疵，原来的a.txt 的修改已经添加到暂存区的，但现在用git stash pop 恢复进度后，a.txt 的修改却还在工作区，暂存区的修改被撤销了。这里其实可以在运行git stash pop命令时带上一个 –index 的选项来告诉git重新应用被暂存的变更。
git stash pop --index
On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: a.txt
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: b.txt
Dropped refs/stash@{0} (c62afccafe9aaec2b44abe85b4206728479b9902)
$ git status
On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: a.txt
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: b.txt
如何撤销工作区的修改？
如果觉得对b.txt这个文件的修改是没有必要的，该如何撤消修改，回到之前的状态（也就是回到没有修改前的状态）？git status 命令输出是有告诉我们怎么做的：
$ git status
On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: a.txt
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: b.txt
就在“Changes not staged for commit”下面第二个括号内，
(use “git checkout – < file >…” to discard changes in working directory)
git checkout – filename 可以丢弃某个文件在工作区的改动。我们试试看。
$ git checkout -- b.txt
$ git status
On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: a.txt
git status 已经没有b.txt 的信息，说明b.txt的修改已经撤出工作区，恢复到修改前的版本了。这里提醒一下：git checkout – filename 这个命令是有点危险的，因为它会丢弃掉之前做的改动，这是找不回来的。只有在确定某个文件是真的不需要改动才撤销。一般情况下，如果只是想回到没修改前的版本，但仍然想保留修改的内容，可以用git stash命令把改动暂存起来。
如何把暂存区的修改撤回到工作区
如果我们不小心把一些还不想提交的修改添加到了暂存区（例如不小心用了 git add . 命令把所有改动都add 到暂存区），我们怎么把某些文件撤回工作区呢？实际上git status命令也有告诉我们。
$ git status
On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: a.txt
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: b.txt
在 “Changes to be committed” 下面，
用 git reset HEAD filename 命令把暂存区的改动撤回到工作区，我们试试。
$ git reset HEAD a.txt
Unstaged changes after reset:
M a.txt
M b.txt
$ git status
On branch 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: a.txt
modified: b.txt
no changes added to commit (use "git add" and/or "git commit -a")
git status 输出可以看到，a.txt 的改动已经被撤出暂存区了。
如何把最近的一次commit撤回到暂存区如果我们对最近的一次commit感到不满意，想把它从本地版本库撤回到暂存区，该怎么做呢？让我们先做一次commit：
git status
On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: a.txt
modified: b.txt
$ git commit -m 'modify a.txt b.txt'
[master c80c16c] modify a.txt b.txt
2 files changed, 2 insertions(+)
$ git log --oneline
c80c16c (HEAD -> master) modify a.txt b.txt
7dd2e09 add two files a.txt b.txt
e6e0035 1.oneline 2.second line
提交已经成功，commitid 为 c80c16c 。现在要撤销这次提交，把改动撤回到暂存区。同样是使用命令 git reset，只不过这次要加上 –soft 选项。
$ git reset --soft HEAD^
$ git status
On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
modified: a.txt
modified: b.txt
git status 输出告诉我们，a.txt 和 b.txt的改动又回到暂存区了。再查看提交历史。
$ git log --oneline7dd2e09 (HEAD -> master) add two files a.txt b.txte6e0035 1.oneline 2.second line
commitid 为 c80c16c 的那次提交已经没有了。现在来解释下 git reset –soft HEAD^ 的含义。先说一下”HEAD^”,它代表最新的一次提交的前一次提交。“HEAD”在Git中就是一个引用，它总是指向（当前分支中）最新的那一次提交。所以上面的命令意思是把头部引用（HEAD）向前回退一次。而选项–soft 的作用就是把最新那次提交的所有改动撤回到暂存区。如何回退已经push到远程版本库的提交上面我们讨论的只是撤销本地做的提交，那如果提交已经push到远程代码库。要怎么回退呢？我们先把上面对a.txt ， b.txt的修改push到远程代码库。
$ git push origin master
Counting objects: 4, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (4/4), 373 bytes | 373.00 KiB/s, done.
Total 4 (delta 0), reused 0 (delta 0)
To github.com:flysqrlboy/git-command-tutorials.git
d7e1e19..f0e0628 master -> master
已push成功，看下提交历史
$ git log --oneline
f0e0628 (HEAD -> master, origin/master) modify a.txt b.txt
d7e1e19 Merge pull request #1 from imflysquirrel/master
0c550df modify b.txt by imflysquirrel
7dd2e09 add two files a.txt b.txt
commitid 为 f0e0628的这次提交已经push到远程。现在想回退远程的这次提交，可能你会想到，先在本地用git reset命令撤销f0e0628 ，再push到远程，这种方案可行吗？试试看：
$ git reset --soft HEAD^
$ git log --oneline
d7e1e19 (HEAD -> master) Merge pull request #1 from imflysquirrel/master
0c550df modify b.txt by imflysquirrel
7dd2e09 add two files a.txt b.txt
执行git reset后本地已经回退到上一次提交，这时我们使用git push推送到远程看看能否成功。 $ git push origin masterTo github.com:flysqrlboy/git-command-tutorials.git ! [rejected] master -> master (non-fast-forward)error: failed to push some refs to 'git@github.com:flysqrlboy/git-command-tutorials.git'hint: Updates were rejected because the tip of your current branch is behindhint: its remote counterpart. Integrate the remote changes (e.g.hint: 'git pull ...') before pushing again.hint: See the 'Note about fast-forwards' in 'git push --help' for details.
推送失败了，reject的原因是说本地当前分支落后于远程代码库，如下hint: Updates were rejected because the tip of your current branch is behind因为我们本地的HEAD引用当前指向的提交是 d7e1e19，而远程的HEAD指向的是f0e0628。d7e1e19落后于f0e0628。其实不应该用git reset来回退远程仓库的提交，取而代之的是用git revert。git revert 这个命令也会创建一次提交，只不过这个提交相当于被回退的那次提交的一个反向提交。比如在f0e0628 这次提交提交中，b.txt增加了一行“Hello World！”，git diff 如下diff --git a/b.txt b/b.txtindex 696ac20..0f47c73 100644--- a/b.txt+++ b/b.txt@@ -1 +1,2 @@ add by imflysquirrel+Hello World!那么反向提交的话就会删掉这行“Hello World!”, 下面用git revert 演示下。$ git revert HEAD[master 9086b68] Revert "modify a.txt b.txt" 2 files changed, 2 deletions(-)git revert HEAD 表示revert HEAD指向的那次提交，也就是最新的那一次提交f0e0628。用git log看下提交历史：git log --oneline9086b68 (HEAD -> master) Revert "modify a.txt b.txt"f0e0628 (origin/master) modify a.txt b.txtd7e1e19 Merge pull request #1 from imflysquirrel/master0c550df modify b.txt by imflysquirrel7dd2e09 add two files a.txt b.txt新增了一个提交9086b68 ，原来的f0e0628 是还存在的。看下这时的b.txt，$ cat b.txtadd by imflysquirrel“Hello World!” 那行已经被删除掉了。那么现在可以push了。$ git push origin masterCounting objects: 3, done.Delta compression using up to 8 threads.Compressing objects: 100% (2/2), done.Writing objects: 100% (3/3), 316 bytes | 316.00 KiB/s, done.Total 3 (delta 1), reused 0 (delta 0)remote: Resolving deltas: 100% (1/1), completed with 1 local object.To github.com:flysqrlboy/git-command-tutorials.git f0e0628..9086b68 master -> masterOk! 成功push 到远程。
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发表于 2019-12-28 17:50:16
