For decades, rsync has been a trusted tool for users looking to copy and back up files seamlessly across drives and computers, both locally and over the Internet. However, due to licensing complications, Apple has decided to replace the traditional rsync command-line tool in its macOS operating system with an alternative known as openrsync. This article delves into the details surrounding this significant change and what it means for users.

The rsync utility, initially developed by Andrew Tridgell and Paul Mackerras and released in 1996, has become synonymous with efficient file transfer. It works by comparing files during the copying process and only transferring those that have been altered since the last backup. This not only saves valuable bandwidth but also significantly reduces the time it takes to complete file transfers, making it a favorite among tech-savvy individuals and system administrators alike.

Over the years, rsync has been incorporated into a wide range of operating systems, including various UNIX flavors, Linux, and even Microsoft Windows through third-party utilities like Cygwin and Grsync. The software is available for free and has been classified as open source, typically under the GNU General Public License (GPL) version 3.0 or later, which includes several restrictions designed to protect users' rights.

Historically, Apple included rsync in its macOS distributions, but the last official version bundled with macOS was 2.6.9. The reason for this limitation can be traced back to the licensing differences; the 2.6.9 version of rsync falls under the GPL 2.0 license, which is less restrictive compared to the GPL 3.0 license. Although newer versions, specifically 3.x, have been released, Apple has opted to forgo their inclusion in macOS due to these licensing challenges.

Instead, Apple has replaced rsync with a variant called openrsync, developed by Kristaps Dzonsons. This alternative maintains much of the functionality that users expect from rsync but operates under a BSD license, which offers more flexibility and fewer restrictions for Apple's needs. While openrsync can perform many of the same tasks as rsync, it is important to note that it is not a direct feature-for-feature replacement.

For those interested in exploring openrsync's capabilities, users can simply type man openrsync in the Terminal app to access a complete list of commands and options. To exit the manual system, users can press Command-Z, Command-C, or the letter 'q' on their keyboard.

Interestingly, even though macOS 15.x Sequoia still ships with the older 2.x version of rsync, if users execute the command rsync --version in Terminal, they will notice a new output indicating: openrsync: protocol version 29, rsync version 2.6.9 compatible. Users who wish to delve deeper into the open-source version can find Kristaps Dzonsons's complete GitHub repository at kristapsdz, while the code for the RsyncProject is also available on GitHub.

For additional guidance on using rsync within macOS, readers can refer to our earlier article entitled How to use SFTP and rsync for file transfers in macOS.

If having the latest 3.x version of rsync (currently 3.4.1) is essential, users can install it via Homebrew. However, caution is advised: doing so will sever Apple's linkage to openrsync within the Mac's filesystem, potentially leading to complications.

Moreover, a graphical user interface (GUI) for rsync, named Grsync, which is based on the GTK libraries and developed by OPByte Software, is also available. While this tool can be quite user-friendly, it has not received updates in recent years, leaving users to evaluate its current reliability.

In summary, the transition from rsync to openrsync reflects Apples ongoing navigation of licensing challenges within the open-source community. Users will need to adapt to this change while remaining aware of their options for file transfer tools in macOS.