add minimal git server blog

blogs/git/git-server.md

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+# create a git user
+
+on debian, `sudo adduser git`
+
+switch to git user with `sudo su -l git`
+
+create a `.ssh` dir in the git user's home dir and make it only accessible by the git user
+
+```
+mkdir ~/.ssh
+chmod 700 ~/.ssh
+```
+
+create an `authorized_keys` file in the `.ssh` folder, and make it accessible only by the git user
+
+```
+touch .ssh/authorized_keys
+chmod 600 `.ssh/authorized_keys`
+```
+
+create a private/public key pair locally to authenticate a user on a machine to connect to the remote server
+
+```
+ssh-keygen -t rsa
+```
+
+and finally copy it into the (remote) git user's `.ssh/authorized_keys`, for example using `ssh-copy-id` or giving the public key to the server administrator.
+
+# creating bare git repositories
+
+create directories within git's home dir (nested paths are allowed) with the `.git` extension, for example `my-projects/my-repo.git` or just `my-repo.git`.
+
+```
+git init --bare repo.git
+```
+
+there now exists an empty git repository on the server.
+
+the remote can now be added to a local repository
+
+```
+git remote add origin git@server:my-repo.git
+git push -u origin main
+```
+
+# connecting using the key
+
+add an entry to your local `.ssh/config`
+
+```
+Host myhost
+    HostName        example.com
+    User            git
+    IdentityFile    ~/.ssh/id_rsa
+```
+
+and connect with
+
+```
+ssh myhost
+```
+