I tried renaming a snap to .zip before opening in file-roller (Archive Manager) but it complained about the file. I did the same for the original .snap file and it opened. It’s not a .tar.gz either.
I need to know so I can recreate the .snap after making modifications to the uncompressed archive.
Snaps are gpg signed squashfs files, you can use unsquashfs from the squashfs-tools package to unpack them…
I dont think there is any sane way to re-compress them without the snapcraft.yaml though (you would have to copy it into snap/ or into the toplevel dir of the unpacked snap and call “snapcraft snap”) and even then you can only install this snap using the --dangerous switch which makes it unupgradeable via “snap refresh”
So this is only feasible for development …
I personally find it easier to simply put a modified file into some workdir and bind mount it on top of the mounted snap to try out a change … or just iteravely rebuild the snap completely for such a use case, This is way less effort …
Thanks ogra. Until about two days ago I was able to copy the .snap to my home directory, open it with file-roller edit the file (.lua in this case) and resave the snap. That’s no longer the case. Maybe an update made an improvement that I’d been exploiting 
I’ve found the git project for the snap itself at https://github.com/snapcrafters/mrrescue so I’ll look into making a clone here so I can make the changes. Many thanks!
