有时git会建议git rm——cached来取消文件，有时git会重置HEAD文件。什么时候用哪个?
D:\code\gt2>git init
Initialized empty Git repository in D:/code/gt2/.git/
D:\code\gt2>touch a
D:\code\gt2>git status
# On branch master
#
# Initial commit
#
# Untracked files:
# (use "git add <file>..." to include in what will be committed)
#
# a
nothing added to commit but untracked files present (use "git add" to track)
D:\code\gt2>git add a
D:\code\gt2>git status
# On branch master
#
# Initial commit
#
# Changes to be committed:
# (use "git rm --cached <file>..." to unstage)
#
# new file: a
#
D:\code\gt2>git commit -m a
[master (root-commit) c271e05] a
0 files changed, 0 insertions(+), 0 deletions(-)
create mode 100644 a
D:\code\gt2>touch b
D:\code\gt2>git status
# On branch master
# Untracked files:
# (use "git add <file>..." to include in what will be committed)
#
# b
nothing added to commit but untracked files present (use "git add" to track)
D:\code\gt2>git add b
D:\code\gt2>git status
# On branch master
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# new file: b
#
我很惊讶没有人提到git reflog (http://git-scm.com/docs/git-reflog):
# git reflog
<find the place before your staged anything>
# git reset HEAD@{1}
reflog是一个git历史记录，它不仅跟踪对repo的更改，还跟踪用户的操作(例如。拉，签出到不同的分支等)，并允许撤销这些操作。因此，与其取消被错误地暂存的文件，还不如恢复到没有暂存文件的位置。
这类似于git reset HEAD <file>，但在某些情况下可能更细粒度。
抱歉，我并没有真正回答你的问题，只是指出了另一种方法来取消我经常使用的文件(我非常喜欢Ryan Stewart和waldyrious的答案);)我希望这能有所帮助。
这个线程有点老了，但我仍然想添加一个小演示，因为它仍然不是一个直观的问题:
me$ git status
# On branch master
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# new file: to-be-added
# modified: to-be-modified
# deleted: to-be-removed
#
me$ git reset -q HEAD to-be-added
# ok
me$ git reset -q HEAD to-be-modified
# ok
me$ git reset -q HEAD to-be-removed
# ok
# or alternatively:
me$ git reset -q HEAD to-be-added to-be-removed to-be-modified
# ok
me$ git status
# On branch master
# Changes not staged for commit:
# (use "git add/rm <file>..." to update what will be committed)
# (use "git checkout -- <file>..." to discard changes in working directory)
#
# modified: to-be-modified
# deleted: to-be-removed
#
# Untracked files:
# (use "git add <file>..." to include in what will be committed)
#
# to-be-added
no changes added to commit (use "git add" and/or "git commit -a")
git reset HEAD(不带-q)给出关于修改文件的警告，其退出码为1，这将被视为脚本中的错误。
Edit: git签出要修改要删除的HEAD也适用于取消暂存，但会将更改完全从工作空间中删除
更新git 2.23.0:命令会不时发生变化。现在，git状态显示:
(use "git restore --staged <file>..." to unstage)
．.． 哪种对这三种变化都有效
