grep over ssh in emacs

M-x grep command is very useful in a number of situation, because, for example, it give you direct access to all matched file ...

But there is not so intuitive how to use grep when opening file via ssh, this is the trick:

First generate a key pair and upload public part to the remote server:
(suppose remote host/user is B/b)

ssh-keygen -t rsa
#...
ssh b@B mkdir -p .ssh
cat ~/.ssh/id_rsa.pub | ssh b@B 'cat >> .ssh/authorized_keys'
ssh-add

be sure to use ssh-agent in order to use ssh-add

So you will not be asked for a password every time you ssh

Every time you want to grep in emacs:

M-x grep
Run grep (like this): ssh -t b@B 'grep -nH -e include path_to_files/*'

where path_to_file is the path relative to home in remote host

NOTE: do grep command when visiting remote home in emacs (otherwise it will not find matched files)

that's all