The Linux community, like any other community, is not particularly good at welcoming new things. Most people want to retain the status quo. In the words of the philosopher Voltaire, the better is the enemy of the good. Nothing is more dangerous than leaving the good for better things.

Systemd, the still controversial system and session manager, illustrates this concept. Other examples are the new package systems Flatpak, Snap, and AppImage, which Linux Magazine previously covered in December 2022 [1]. These package systems are by no means met with unanimous approval in the Linux community. In particular, the Snap format, which Canonical initially designed for cloud applications and the Internet of Things (IoT), but later ported for desktop applications, is experiencing opposition beyond the basic criticism of new package systems.

If you've become disillusioned with Snap, the unsnap script can help you replace snaps with Flatpaks where available on Ubuntu and its deriviatives.

Bad Experiences

The Linux community is skeptical of any solo efforts by Canonical due to bad past experiences. The main criticisms leveled at Snap (Figure 1) are the Snap Store's proprietary back end [2] and the fact that Canonical is increasingly pushing the format in Ubuntu, with no official way to remove snaps.

Figure 1: When you install programs via Ubuntu Software, you can define the source via a selection box top right. Some packages, such as Firefox, are generally only available as snaps.

The snap daemon (snapd) is the defined tool for retrieving snaps and all associated metadata from Canonical's servers. In addition, snaps have functional drawbacks that the company has been slow to eliminate. Flatpak, on the other hand, was well received by proponents of alternative package systems. Flatpak is probably the choice of most users outside the Ubuntu environment. This could eventually lead to Canonical mothballing Snap again, as has often been the case in the past with in-house developments such as Ubuntu Touch or the Mir display manager.

This situation has led some distributions to reject or even block snaps. One prominent example is Linux Mint, based on Ubuntu LTS, whose developers decided as early as 2020 not to deliver snaps [3]. They also announced that Linux Mint, starting in version 20, would actively prevent the installation of the Snap framework via the graphical package manager, preventing snaps from automatically ending up on the user's system through the backdoor.

Laptop manufacturers System76 (Pop!_OS) and Tuxedo (Tuxedo OS 1) also avoid shipping snaps with their Ubuntu derivatives. Even Ubuntu users have not rallied behind Snap, as suggested by many guides that describe installing Firefox in Ubuntu as a DEB.

unsnap

Former Snap co-developer Alan Pope, who left Canonical in 2021 after 10 years with the company, has developed unsnap [4], a script that replaces snaps with Flatpaks where available. The script, hosted on GitHub, has been tested by the developers for use on Ubuntu and all derivatives that offer snapd and packages in the Snap format.

To test unsnap on a freshly installed Ubuntu 22.04 LTS, I set up a few more packages from the Snap Store in addition to the existing snaps via the Ubuntu Software package manager and then listed them just to be sure (Figure 2). I then downloaded the unsnap script from GitHub. To do this, I first had to install the git package and then run the command from Listing 1.

$ git clone https://github.com/popey/unsnap

Figure 2: The snap list command lists all snaps installed on the system.

Before getting into the nitty gritty, let's take a look at how the script works. Immediately after startup, unsnap creates a log directory in which it generates six additional scripts tailored to the particular system (see Table 1). The applist.csv [5] file is used to find Flatpaks that match the installed snaps.

Multiple Steps

To start the script, first change to the appropriate directory by typing cd unsnap. The ./unsnap command (Figure 3) first informs you that various checks will be run to determine if Flatpak is already installed and Flathub is included, as well as which snaps have Flatpak equivalents.

Figure 3: If you call the script without additional commands, it determines the system status and creates the required auxiliary scripts, which you can then launch manually, if required.

Next, unsnap creates the helper scripts. If you have a reason not to run one of the helper scripts, you can launch these scripts manually one after the other. Otherwise, call ./unsnap auto to automatically install the scripts (Figure 4).

Figure 4: If the script is called with the ./unsnap auto command, the process completes automatically.

On my lab system, I installed about 20 snaps, of which unsnap was able to replace about half. However, I intentionally installed snaps such as the Canonical Juju and LXD tools, as well as the Mutt command-line email client, to test how the script responded (Figure 5). In general, the chances of finding a Flatpak counterpart for graphical apps are better, because Flatpak targets the desktop. Snap, on the other hand, also targets the server world.

Figure 5: There is not always a Flatpak equivalent for installed snaps; unsnap lists these cases separately.