rsync ignore existing

Guri Bee

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19-10-2024

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Mastering rsync: Ignore Existing Files with Precision

Rsync is a powerful tool for synchronizing files and directories between systems. But what happens when you want to transfer data while preserving existing files on the destination? This is where the --ignore-existing option comes in handy.

Understanding the Need for --ignore-existing

Let's imagine you're updating a web server. You've made changes to your website's files locally, but you don't want to overwrite files on the server that are already up-to-date. This is where --ignore-existing shines.

How --ignore-existing Works

The --ignore-existing option tells rsync to skip transferring files that already exist on the destination. It does this by comparing timestamps and file sizes. If the file on the destination is newer or the same size as the source file, it's skipped.

Simple Example: Updating Website Files

Let's say you have a website directory called "mywebsite" locally and a server at "mysite.com". You want to update the files but leave existing files untouched. You can use the following command:

rsync -avz --ignore-existing mywebsite/ [email protected]:/path/to/website

This command:

• -a: Archives the files (retains permissions, timestamps, etc.)
• -v: Enables verbose output for detailed information
• -z: Compresses data for faster transfers
• --ignore-existing: Ignores files that already exist on the server

Important Considerations:

• Incremental Transfers: --ignore-existing is particularly useful for incremental backups or synchronizing large data sets where you only want to transfer new or modified files.
• File Timestamps: Rsync relies on timestamps to determine if a file needs to be transferred. If timestamps are not reliable (e.g., files are moved without updating timestamps), you might want to consider using the --update option for more accurate results.
• Deleting Files: --ignore-existing does not delete files on the destination that are not present on the source. If you want to remove files on the destination that are not present on the source, you can use the --delete option.

Going Beyond the Basics: Advanced Use Cases

1. Selective File Transfers:

You can combine --ignore-existing with other rsync options to achieve more granular control. For example, to transfer only files that are newer on the source, you can use:

rsync -avz --ignore-existing --update mywebsite/ [email protected]:/path/to/website

2. Large File Transfers:

For large files, you can use the --partial option to resume transfers in case of interruptions.

rsync -avz --ignore-existing --partial mywebsite/ [email protected]:/path/to/website

3. File Exclusion:

To exclude specific files or directories during the transfer, you can use the --exclude option:

rsync -avz --ignore-existing --exclude "*.log" mywebsite/ [email protected]:/path/to/website

Conclusion

--ignore-existing is an essential option for efficiently syncing files while preserving existing files on the destination. By understanding its functionality and combining it with other rsync options, you can achieve highly granular control over your data transfer process.

This article has been created using information found in the following Github repositories:

• rsync man page
• Rsync documentation

Note: This article provides a general overview of the --ignore-existing option and is not intended as a comprehensive guide to rsync. Please consult the official documentation for detailed information and advanced use cases.