Git

root from absolute path

git rev-parse --show-toplevel

• HOW view diff version of one file in two branch

the mybranch is new than master: git diff old..new should be write master..mybranch will be add + after any new line created by mybranch

(master) \$ cat file.txt 
a
c

(mybranch) \$ cat file.txt 
a
b
c

git diff master..mybranch -- /file1

 a
+b
 c

• view diff bitween to dirs

\$ diff -rq ./dir1 ./dir2

• git back/reset/restor/revet

\$ git reset --hard 6bc2e3a

• diff new file only:

git diff --name-only  --diff-filter=A 65833e30..c3098905

• submodule

git clone --recurse-submodules -j8 git://github.com/foo/bar.git
git submodule update --init --recursive