Rsync (Remote Sync) is a most commonly used command for copying and synchronizing files and directories remotely as well as locally in Linux/Unix systems. With the help of rsync command, you can copy and synchronize your data remotely and locally across directories, across disks and networks, perform data backups and mirroring between two Linux machines. However, errors such as “protocol version mismatch — is your shell clean?” or “protocol initialization failed” are quite common with rsync. These errors occur when the remote shell is not acting cleanly –i.e., there is additional garbage or message that is added to the command output.
There are several solutions that one can apply to fix this issue:
1. Check Your Shell Configuration: Whenever you login to your server, .bashrc or .bash\_profile are the two files that are being read and executed by your shell. When something is outputted here, you will encounter errors in rsync. One solution is to remove any trace of echo or print commands that might output additional messages when you log in this shell.
NOTE: Before making any modifications to your system, it’s recommended to backup all important data and configuration info. Always review the official documentation before making changes to a production environment.
1. Check SSH settings: Another possible solution is to try SSH and observe if it creates a lot of output lines. SSH could be generating output that interrupts rsync. You can fix this either by proving -q to rsync.
1. Specific Rsync Command Use: While using the rsync command, you should use it in a specific way to avoid these errors. Some users have found success with the following command: `rsync -avz -e “ssh -q” /Source_directory/ user@remote_host:/Destination_directory` This command avoids verbose SSH output which can cause a protocol initialization failure.
1. Debugging: In some cases, you might want to debug the issue further. To do this, you can add -vvv to your rsync command which will increase the verbosity of rsync and print detailed information about what rsync is doing which can help identify the exact issue.
1. Upgrade rsync version: If nothing works, you might want to upgrade the version of rsync on your machine and on the machine you are trying to rsync from. Different versions of rsync sometimes interact incorrectly due to changes in the protocol which can cause a protocol initialization failure.
1. Less secure but quick option: Another alternative is to use the rsync daemon directly to serve files. Although this method does not encrypt network traffic so it’s not advisable unless it’s specified within the configuration.
All of these solutions have been compiled from various sources including StackOverflow, TecMint, and man pages of the rsync command from a Linux terminal.
{% include note.html content=“Always review the official documentation before making changes to a production environment. And make sure to backup all important data and configuration info before making any modifications to your system.” %}
