add a memo about git

memo/git-remote.md

@@ -0,0 +1,108 @@
+## Gitea with custom SSH port
+
+Since in most cases Gitea will be deployed within containers, it cannot use the same port (`22`) as the host machine to handle git operations via SSH. In my case the port `222` is used instead. Meanwhiles, this can cause some extra steps to set the correct remote URL for local repositories, since the port is different from the default one.
+
+There are few approaches to handle this:
+
+1. Edit `~/.ssh/config`
+
+like:
+
+```
+Host gitea
+    HostName git.example.tld
+    User git
+    Port 222
+    IdentityFile /path/to/private/key
+```
+
+then:
+
+```sh
+git remote add origin gitea:username/repo.git
+```
+
+2. Use full URL with port
+
+> [!WARNING]
+>
+> The `scp`-like syntax `user@host:repo.git` does not support port specification. `ssh://` URL scheme must be used instead.
+
+```sh
+git remote add origin ssh://git@example.tld:222/username/repo.git
+```
+
+3. Use `GIT_SSH_COMMAND` environment variable
+
+```sh
+GIT_SSH_COMMAND='ssh -p 222'
+```
+
+4. and more...
+   - aliases
+   - scripts
+   - etc.
+
+## Local Repo with Multiple Remotes
+
+> [!TIP]
+>
+> Check current remotes with:
+>
+> ```sh
+> git remote -v
+> ```
+>
+> and remove a remote with:
+>
+> ```sh
+> git remote remove <name>
+> ```
+
+Local repositories can have multiple remotes configured. This is useful when pushing to the primary repository and also to a backup repository.
+
+And there are multiple ways to add multiple remotes:
+
+1. Use different names for remotes
+
+```sh
+git remote add origin ssh://git@example.tld/username/repo.git
+
+git remote add backup ssh://git@backup.tld/username/repo.git
+```
+
+then push to both remotes:
+
+```sh
+git push origin main
+git push backup main
+```
+
+Without referring to remotes explicitly, git will use `origin` by default. To fetch from all remotes, use `git fetch --all` or directly `git pull --all`.
+
+> [!NOTE]
+>
+> The command `git push --all` is for pushing all local branches, not for pushing to all configured remote URLs.
+
+2. Use `git remote set-url --add`
+
+```sh
+git remote set-url --add origin ssh://git@example.tld/username/repo.git
+git remote set-url --add origin ssh://git@backup.tld/username/repo.git
+```
+
+then push to both remotes:
+
+```sh
+git push origin
+```
+
+A single `git push origin` will push to all URLs configured for the `origin` remote.
+
+> [!IMPORTANT]
+>
+> By default, `git fetch` and `git pull` will only interact with the first (fetch) URL configured for a remote.
+>
+> The `git fetch --all` command fetches from all configured **remotes** (e.g., `origin`, `backup`), not from all URLs within a single remote.
+>
+> Similarly, `git pull --all` will first run `git fetch --all` and then merge the current local branch with its upstream branch. The merge action only applies to the current branch.