超级有用的git reset --hard和git revert命令

很多时候，git新手容易误操作，比如，在levelIISZ-1.4.dev分支下，运行了git pull idc cpp-1.0的结果，这样做麻烦很大，经常导致maven项目格式不正确，这个时候，可以用git reset --hard 去撤销这次修改

但是这样做也有问题，可能之前本地的，没有提交的修改，都消失了。可以尝试git revert命令

reset是指将当前head的内容重置，不会留任何痕迹。

Sets the current head to the specified commit and optionally resets the index and working tree to match.

git reset --hard HEAD~3

会将最新的3次提交全部重置，就像没有提交过一样。

根据--soft --mixed --hard，会对working tree和index和HEAD进行重置。

revert是撤销某次提交，但是这次撤销也会作为一次提交进行保存(这样就不会丢失原来修改过，但是没有提交的内容？)。

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非常好的一篇文章
http://alpha-blog.wanglianghome.org/2010/07/30/git-partial-rollback/
如何使用git回退部分修改

人总有犯错误的时候，如果发现不小心把私货提交到公共代码库，改如何挽回呢？

例如如下代码库：

$ mkdir git-partial-revert

$ cd git-partial-revert

$ echo "hello a" >a.txt

$ echo "hello b" >b.txt

$ git init

Initialized empty Git repository in /home/liang/project/git/git-partial-revert/.git/

$ git add *.txt

$ git commit -m "initial version"

[master (root-commit) b5e1a24] initial version

2 files changed, 2 insertions(+), 0 deletions(-)

create mode 100644 a.txt

create mode 100644 b.txt

$ git log

commit b5e1a24fc65202977b903435750dd9fb5e0d04d0

Author: Liang Wang <a@b.c>

Date: Fri Jul 30 13:20:38 2010 +0800

initial version

以下是一次错误的修改。

$ echo "hello a from b" >>a.txt

$ echo "hello b from a" >>b.txt

$ git commit -a -m "hello a from b"

[master df3144e] hello a from b

2 files changed, 2 insertions(+), 0 deletions(-)

$ git push origin master

$ git log

commit df3144e3168f6ec189ed0b2b57908d8d4e862fe5

Author: Liang Wang <a@b.c>

Date: Fri Jul 30 13:22:51 2010 +0800

hello a from b

commit b5e1a24fc65202977b903435750dd9fb5e0d04d0

Author: Liang Wang <a@b.c>

Date: Fri Jul 30 13:20:38 2010 +0800

initial version

错误在于只应该提交对于a.txt的修改，b.txt的修改是私货，应该留在本地，以后提交。

第一种方法：纯手工修改。取决于要修改的内容多少，这可能是最简单也可能是最笨的方法。

如果错误发生在最新的commit里面，可以使用git reset修改。如下：

$ git reset b5e1a24f -- b.txt

Unstaged changes after reset:

M b.txt

$ cat b.txt

hello b

hello b from a

$ git log

commit df3144e3168f6ec189ed0b2b57908d8d4e862fe5

Author: Liang Wang <lwang1@marvell.com>

Date: Fri Jul 30 13:22:51 2010 +0800

hello a from b

commit b5e1a24fc65202977b903435750dd9fb5e0d04d0

Author: Liang Wang <a@b.c>

Date: Fri Jul 30 13:20:38 2010 +0800

initial version

$ git diff

diff --git a/b.txt b/b.txt

index b1bdbca..ab47375 100644

--- a/b.txt

+++ b/b.txt

@@ -1 +1,2 @@

hello b

+hello b from a

$ git status

# On branch master

# Changes to be committed:

# (use "git reset HEAD <file>..." to unstage)

#

# modified: b.txt

#

# Changed but not updated:

# (use "git add <file>..." to update what will be committed)

# (use "git checkout -- <file>..." to discard changes in working directory)

#

# modified: b.txt

#

$ git diff --cached

diff --git a/b.txt b/b.txt

index ab47375..b1bdbca 100644

--- a/b.txt

+++ b/b.txt

@@ -1,2 +1 @@

hello b

-hello b from a

$ git commit -m "revert change in b"

[master d49f9f2] revert change in b

1 files changed, 0 insertions(+), 1 deletions(-)

$ git push origin master

$ git status

# On branch master

# Changed but not updated:

# (use "git add <file>..." to update what will be committed)

# (use "git checkout -- <file>..." to discard changes in working directory)

#

# modified: b.txt

#

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

$ git diff

diff --git a/b.txt b/b.txt

index b1bdbca..ab47375 100644

--- a/b.txt

+++ b/b.txt

@@ -1 +1,2 @@

hello b

+hello b from a

$ git log --stat

commit d49f9f2531ed9106ea53006bd698bbcdd54698e9

Author: Liang Wang <a@b.c>

Date: Fri Jul 30 13:34:43 2010 +0800

revert change in b

b.txt | 1 -

1 files changed, 0 insertions(+), 1 deletions(-)

commit df3144e3168f6ec189ed0b2b57908d8d4e862fe5

Author: Liang Wang <a@b.c>

Date: Fri Jul 30 13:22:51 2010 +0800

hello a from b

a.txt | 1 +

b.txt | 1 +

2 files changed, 2 insertions(+), 0 deletions(-)

commit b5e1a24fc65202977b903435750dd9fb5e0d04d0

Author: Liang Wang <a@b.c>

Date: Fri Jul 30 13:20:38 2010 +0800

initial version

a.txt | 1 +

b.txt | 1 +

2 files changed, 2 insertions(+), 0 deletions(-)

这时b的修改就从公共代码库上拿掉了，但是还保留在本地。

或者也可以使用git revert。下面操作的缺点是没有保留对于b.txt的修改。如何保留修改留给读者作为习题 :-)

$ git revert -n df3144e31

Finished one revert.

$ git status

# On branch master

# Changes to be committed:

# (use "git reset HEAD <file>..." to unstage)

#

# modified: a.txt

# modified: b.txt

#

$ git diff --cached

diff --git a/a.txt b/a.txt

index 2c5e468..74614c9 100644

--- a/a.txt

+++ b/a.txt

@@ -1,2 +1 @@

hello a

-hello a from b

diff --git a/b.txt b/b.txt

index ab47375..b1bdbca 100644

--- a/b.txt

+++ b/b.txt

@@ -1,2 +1 @@

hello b

-hello b from a

$ git reset HEAD a.txt

Unstaged changes after reset:

M a.txt

$ cat a.txt

hello a

$ git checkout -- a.txt

$ cat a.txt

hello a

hello a from b

$ cat b.txt

hello b

$ git commit -m "revert change in b"

[master 5f6a2e1] revert change in b

1 files changed, 0 insertions(+), 1 deletions(-)

$ git log --stat

commit 5f6a2e16bfd59281d0150e3644aa1485dd6c0078

Author: Liang Wang <a@b.c>

Date: Fri Jul 30 14:17:44 2010 +0800

revert change in b

b.txt | 1 -

1 files changed, 0 insertions(+), 1 deletions(-)

commit df3144e3168f6ec189ed0b2b57908d8d4e862fe5

Author: Liang Wang <a@b.c>

Date: Fri Jul 30 13:22:51 2010 +0800

hello a from b

a.txt | 1 +

b.txt | 1 +

2 files changed, 2 insertions(+), 0 deletions(-)

commit b5e1a24fc65202977b903435750dd9fb5e0d04d0

Author: Liang Wang <a@b.c>

Date: Fri Jul 30 13:20:38 2010 +0800

initial version

a.txt | 1 +

b.txt | 1 +

2 files changed, 2 insertions(+), 0 deletions(-)

如果错误的修改已经不是最新的commit，则只能使用git revert。

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我们teamleader的总结，很不错的！！！
http://guibin.iteye.com/blog/101436