copying

remote2remote_rsync.md

Cheat Sheet: Copying Folders Between Remote Servers

This guide uses rsync and SSH Agent Forwarding to securely and efficiently copy folders between two servers.

Method 1: Push from Source Server 📤

Use this when you can SSH into the source server.

1. On Your Local PC (Prep Agent): Load the key for the destination server.

   eval $(ssh-agent -s)
   ssh-add ~/.ssh/key_for_dest_server

2. On Your Local PC (Connect to Source): Use -A to forward your agent.

   ssh -A user@source-server

3. On the Source Server (Push with rsync):

   • To copy the folder itself:

     rsync -avz /path/to/folder user@dest-server:/path/to/destination/

   • To copy only the folder's contents:

     rsync -avz /path/to/folder/ user@dest-server:/path/to/destination/

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Method 2: Pull to Destination Server 📥

Use this when you can only SSH into the destination server.

1. On Your Local PC (Prep Agent): Load the key for the source server.

   eval $(ssh-agent -s)
   ssh-add ~/.ssh/key_for_source_server

2. On Your Local PC (Connect to Destination): Use -A to forward your agent.

   ssh -A user@dest-server

3. On the Destination Server (Pull with rsync):

   • To copy the folder itself:

     rsync -avz user@source-server:/path/to/folder /path/on/this/server/

   • To copy only the folder's contents:

     rsync -avz user@source-server:/path/to/folder/ /path/on/this/server/

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💡 Key Reminders

• SSH Agent Forwarding (ssh -A): This is the magic that lets a remote server securely use your local SSH keys. If you get a Permission denied error, the first thing to check on your local PC is ssh-add -l to see if the correct key is loaded.
• The rsync Trailing Slash: This is critical.
  • /folder ➡️ copies the folder itself.
  • /folder/ ➡️ copies only the contents inside the folder.
• rsync -avz flags:
  • a: archive mode (preserves everything).
  • v: verbose (shows progress).
  • z: compress (speeds up transfer).