update git

IT/git/Git.md

@@ -23,8 +23,22 @@ this will ask if you want to add each modification with this option:
 ## delete a file from complete history
 
 be carefull can't push repo last time use
+need to be in a repo with no modification
 
-`git filter-branch --tree-filter 'rm -f passwords.txt' HEAD`
+```
+git filter-branch --index-filter "git rm -rf --cached --ignore-unmatch $file" HEAD 
+rm -rf .git/refs/original/ && git reflog expire --all &&  git gc --aggressive --prune
+```
+
+## create a repo from other repo subfoler
+
+- clone the first repo
+- go in this directory
+- launch
+```
+git filter-branch --prune-empty --subdirectory-filter "subdirectory/path" master
+```
+- push in your new git repo
 
 ## changing email adress