git命令 add -a和add .和add -u 的区别

总结：

• git add -a 所有的更改操作--新建，更改，删除；
• git add . 只包括 新建 ，修改操作；无删除；
• git add -u 只包括修改，删除操作，无新建；

示例：

git init
echo Change me > change-me
echo Delete me > delete-me
git add change-me delete-me
git commit -m initial

echo OK >> change-me
rm delete-me
echo Add me > add-me

git status
# Changed but not updated:
#   modified:   change-me
#   deleted:    delete-me
# Untracked files:
#   add-me

git add .
git status

# Changes to be committed:
#   new file:   add-me
#   modified:   change-me
# Changed but not updated:
#   deleted:    delete-me

git reset

git add -u
git status

# Changes to be committed:
#   modified:   change-me
#   deleted:    delete-me
# Untracked files:
#   add-me

git reset

git add -A
git status

# Changes to be committed:
#   new file:   add-me
#   modified:   change-me
#   deleted:    delete-me

Summary:

• git add -Astages All
• git add .stages new and modified, without deleted
• git add -ustages modified and deleted, without new

参考：http://stackoverflow.com/questions/572549/difference-of-git-add-a-and-git-add