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撤销更改
相信你已经了解了 git 的基本概念, 也清楚了工作区, 暂存区和版本库的关系, 现在让我们用所学的知识继解决实际问题吧!
背景
正常看得见的目录是我们最为熟悉的工作区, 在工作中不可能总是 100% 的精力, 难免会犯错, 尤其是下午犯困, 晚上加班更是如此. 下面列举了常见的一些场景
场景一: 工作区出现意外更改且尚未添加到暂存区
北京时间现在是晚上 10 点钟, 你正在赶制一份工作报告, 尽管心中一万个不愿意, 还是不得不做.
开始模拟意外更改前, 先查看一下 test.txt 文件相关信息:
# 列出当前目录的文件
$ ls
file1.txt file2.txt file3.txt newFile.txt test.txt
# 查看 `test.txt` 文件内容
$ cat test.txt
git test
git init
git diff
understand how git control version
how git work
git tracks changes of files
# 查看 `test.txt` 文件状态
$ 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: test.txt
Untracked files:
(use “git add <file>…” to include in what will be committed)
.DS_Store
no changes added to commit (use “git add” and/or “git commit -a”)
# 查看 `test.txt` 文件差异
$ git diff
diff –git a/test.txt b/test.txt
index d31bdd2..56c76b7 100644
— a/test.txt
+++ b/test.txt
@@ -3,4 +3,4 @@ git init
git diff
understand how git control version
how git work
-git tracks changes
+git tracks changes of files
$
还记得在上一节中我们讲解 git 版本控制的到底是什么, 为了证明 git 管理的是更改而不是文件本身, 我们特意在第二次更改时没有添加到暂存区, 现在我们先把这个遗留问题解决掉.
# 工作区更改添加到暂存区
$ git add test.txt
# 暂存区内容提交到版本没哭
$ git commit -m “git tracks changes of files”
[master b7bda05] git tracks changes of files
1 file changed, 1 insertion(+), 1 deletion(-)
# 查看文件状态
$ git status
On branch master
Untracked files:
(use “git add <file>…” to include in what will be committed)
.DS_Store
nothing added to commit but untracked files present (use “git add” to track)
$
现在正在加班加点干活, 一不小心将心中的不满表露出来了, 于是有了下面的内容:
# 意外更改正是这么犯傻的一句话
$ echo “My stupid boss still prefers svn” >> test.txt
# 当前文件内容
$ cat test.txt
git test
git init
git diff
understand how git control version
how git work
git tracks changes of files
My stupid boss still prefers svn
$
虽然强打精神, 可还是很困, 于是打算喝杯咖啡提提神, 猛然发现 stupid boss 可能会让你丢掉这个月的奖金!
暗自庆幸, 咖啡果然是个好东西, 既然发现了问题, 那就事不宜迟赶紧修复, 因为不适宜的话正是 stupid boss , 所以你完全可以手动删除, 但是假如你说了一大堆不合适的话, 或者复制粘贴时弄错了, 这就不是删除一两行那么简单了!
既然手动解决比较麻烦, 那 git 有没有什么好方法来解决这类问题呢? 在寻求 git 帮助前, 首先再看一下当前文件状态(git status). 正所谓 ” 知己知彼方能百战百胜 ”, 还是看一眼吧!
# 查看文件状态
$ 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: test.txt
Untracked files:
(use “git add <file>…” to include in what will be committed)
.DS_Store
no changes added to commit (use “git add” and/or “git commit -a”)
$
git 不负众望, 果然给了我们希望,(use “git checkout — <file>…” to discard changes in working directory) 这句话的告诉我们可以丢弃工作区的更改!
脑海中在快速回忆一下工作区, 暂存区, 版本库三者之间的关系, 其实 git checkout — <file> 命令的意思是用暂存区的内容替换掉工作区内容, 因此也就是丢弃掉工作区的更改了.
事不宜迟, 运行 git checkout — <file> 命令试试看吧:
# 丢弃工作区的更改
$ git checkout — test.txt
# 查看文件内容: My stupid boss still prefers svn 终于不见了
$ cat test.txt
git test
git init
git diff
understand how git control version
how git work
git tracks changes of files
# 查看文件状态
$ git status
On branch master
Untracked files:
(use “git add <file>…” to include in what will be committed)
.DS_Store
nothing added to commit but untracked files present (use “git add” to track)
$
一顿操作猛如虎, 撤销掉意外更改, 回到上一次版本控制状态, 世界如此美好 …
注意: git checkout — <file> 中的 — 至关重要, 没有它就是切换分支了!
场景二: 工作区出现意外更改且已经添加到暂存区, 但尚未提交到版本库
时间一分一秒过去了, 转眼间已经 11 点了, 假设你不但写了一些胡话, 还添加到暂存区了(git add). 可想而知, 这次意外比场景一要糟糕.
# 模拟正常提交(不然岂不是从场景一到场景二你什么都没做, 那还能叫做赶制工作报告吗?!)
$ echo “someone prefers svn,but i don’t care it” >> test.txt
$ cat test.txt
git test
git init
git diff
understand how git control version
how git work
git tracks changes of files
someone prefers svn,but i don’t care it
$ git add test.txt
$ git commit -m “normal commit”
[master ab1cbd2] normal commit
1 file changed, 1 insertion(+)
# 意外更改的前夕
$ cat test.txt
git test
git init
git diff
understand how git control version
how git work
git tracks changes of files
someone prefers svn,but i don’t care it
# 意外更改内容: my teammate is stupid too.
$ echo “my teammate is stupid too.” >> test.txt
$ cat test.txt
git test
git init
git diff
understand how git control version
how git work
git tracks changes of files
someone prefers svn,but i don’t care it
my teammate is stupid too.
# 意外操作: 将意外更改内容提交到暂存区
$ git add test.txt
不过庆幸的是, 在提交到版本库 (git commit) 之前及时发现问题, 还是看一下现在的文件状态 (git status) 吧!
# 查看文件状态: 救命稻草 (use “git reset HEAD <file>…” to unstage)
$ git status
On branch master
Changes to be committed:
(use “git reset HEAD <file>…” to unstage)
modified: test.txt
Untracked files:
(use “git add <file>…” to include in what will be committed)
.DS_Store
$
git 同样告诉我们, 可以使用 git reset HEAD <file> 命令撤销暂存区更改.
其实 git reset HEAD <file> 命令是用版本库的内容替换掉暂存区的内容, 也就是说原来暂存区的内容已被丢弃了!
所以说这个命令并不会影响工作区内容, 不如我们现在再看一眼工作区内容, 方便执行 git reset HEAD <file> 命令后证实我们的结论.
# 查看文件内容: my teammate is stupid too.
$ cat test.txt
git test
git init
git diff
understand how git control version
how git work
git tracks changes of files
someone prefers svn,but i don’t care it
my teammate is stupid too.
$
迫不及待执行 git reset HEAD <file> 命令, 先睹为快!
# 救命稻草: 版本库内容替换掉暂存区内容
$ git reset HEAD test.txt
Unstaged changes after reset:
M test.txt
# 效果: 目标文件已修改但未添加到暂存区
$ 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: test.txt
Untracked files:
(use “git add <file>…” to include in what will be committed)
.DS_Store
no changes added to commit (use “git add” and/or “git commit -a”)
# 目标文件内容: 仍然保持不变
$ cat test.txt
git test
git init
git diff
understand how git control version
how git work
git tracks changes of files
someone prefers svn,but i don’t care it
my teammate is stupid too.
$
现在场景二已经退化成场景一了, 目标文件发生意外更改但还没添加到暂存区, 如何撤销工作区更改, 请参考场景一方法.
提示: git checkout — test.txt
场景三: 工作区出现意外更改不仅已添加到暂存区, 还已提交到版本库, 但尚未推送到远程仓库
时间不紧不慢地已经到凌晨了, 困意越来越浓, 洋洋洒洒写下几千字的工作报告, 总算是写完了, 添加到暂存区 (git add), 提交到版本库(git commit) 一气呵成, 等等, 好像有什么不对劲, 难免会犯糊涂, 这不又发生意外了!
# 衔接场景二
$ cat test.txt
git test
git init
git diff
understand how git control version
how git work
git tracks changes of files
someone prefers svn,but i don’t care it
# 正常提交一
$ echo “i love working,work makes me happy” >> test.txt
$ git add test.txt
$ git commit -m “encourage myself”
[master a44cf7a] encourage myself
1 file changed, 1 insertion(+)
# 正常提交二
$ echo “fix 110 bugs,so happy” >> test.txt
$ git add test.txt
$ git commit -m “fix bugs”
[master c66399d] fix bugs
1 file changed, 1 insertion(+)
sunpodeMacBook-Pro:demo sunpo$ git status
On branch master
Untracked files:
(use “git add <file>…” to include in what will be committed)
.DS_Store
nothing added to commit but untracked files present (use “git add” to track)
# 意外更改: hate to work overtime
$ echo “hate to work overtime” >> test.txt
$ git add test.txt
$ git commit -m “test.txt”
[master c965724] test.txt
1 file changed, 1 insertion(+)
$
天妒英才, 加班加点做事情, 本想赢得老板的赏识, 没想到最后一句话 ”hate to work overtime” 让所有的努力都付之一炬, 怎么办?
死马当活马医, 还是照例看看 git status 能提供什么建议吧!
$ git status
On branch master
Untracked files:
(use “git add <file>…” to include in what will be committed)
.DS_Store
nothing added to commit but untracked files present (use “git add” to track)
$
没有提供任何意见能帮助我们撤销意外更改, 先别慌, 容我深思三秒钟 …
既然意外更改已经提交到版本库, 那么应该用什么内容替换版本库内容呢? 有了, 既然最新版本库不可用, 那上一个版本库内容可用的啊, 完全可以用上一个版本库内容替换最新版本库内容, 真乃 ” 天生我材必有用 ”!
# 当前文件内容: 闯祸的 ”hate to work overtime”
$ cat test.txt
git test
git init
git diff
understand how git control version
how git work
git tracks changes of files
someone prefers svn,but i don’t care it
i love working,work makes me happy
fix 110 bugs,so happy
hate to work overtime
# 版本回退: 回到过去假装什么都没发生过
$ git reset –hard HEAD^
HEAD is now at c66399d fix bugs
sunpodeMacBook-Pro:demo sunpo$ git status
On branch master
Untracked files:
(use “git add <file>…” to include in what will be committed)
.DS_Store
nothing added to commit but untracked files present (use “git add” to track)
# 岁月静好, 一切似乎都没发生过
$ cat test.txt
git test
git init
git diff
understand how git control version
how git work
git tracks changes of files
someone prefers svn,but i don’t care it
i love working,work makes me happy
fix 110 bugs,so happy
# 当前文件状态
$ git status
On branch master
Untracked files:
(use “git add <file>…” to include in what will be committed)
.DS_Store
nothing added to commit but untracked files present (use “git add” to track)
$
详情请参考回到过去, 时空穿越之旅就是这么方便哈!
提示: git reset –hard HEAD^
场景四: 工作区出现意外更改不仅已添加到暂存区, 还提交到版本库, 还已推送到远程仓库
场景一到场景三都是本地仓库, 所有的文件更改只能本机访问, 小伙伴也好, 上级领导也罢都无法查看到你本地更改, 但是一旦你推送到远程仓库了, 那么其他人就能查看你的更改了!
正常的提交更改还好, 怕就怕这种 ”stupid boss” 被领导看到就不好了, 那应该怎么办? 暂时还是自求多福吧!
小结
丢弃工作区更改: git checkout — <file>
丢弃暂存区更改: git reset HEAD <file>
丢弃本地版本库更改: git reset –hard HEAD^
丢弃远程版本库更改: 自求多福
