Without changing their extension:
As such, an appimage can be mounted or extracted. That is:
To mount them:
The AppImage is unmounted when the application called in the example
is interrupted (e.g., by pressing Ctrl+C, closing the terminal etc.).
Note: This is only available for type 2 AppImages. Type 1 AppImages do
not provide any self-mounting mechanism. To mount type 1 AppImages,
mount -o loop
To extract them:
An alternative to mounting the AppImages is to extract their contents.
This allows for modifying the contents. The resulting directory is a
valid AppDir, and users can create AppImages from them again using
Analog to mounting AppImages, there is a simple commandline switch to
extract the contents of type 2 AppImages without external tools. Just
call the AppImage with the parameter
--appimage-extract. This will
cause the runtime to create a new directory called
containing the contents of the AppImage’s AppDir specification.
Type 1 AppImages require the deprecated tool
extract the contents of an AppImage. It’s very limited functionality
wise, and requires a GUI to run. It creates a new directory in the
user’s desktop directory.
There is an answer on superuser on how to extract files from an AppImage.
Looking at my appimages I see that only some of them can be mounted with gnome-disk-image-mounter. Also here.
Changing their extension:
Not all appimages have exactly the same structure, but all are archives. Wikipedia says: "An AppImage of version 1.0 is an ISO 9660 Rock Ridge file (which can be optionally zisofs compressed) containing a minimal AppDir and a tiny runtime. (Version 2 may use other file system image formats like SquashFS)".
So, it can be extracted. In this way you can examine the files.
Simply changing the extension from
AppImage to an archive extension that my file-roller archive manager can read (I tested with
7z, etc) and double-clicking the file reveals the contents in file-roller:
They can also be extracted, of course. The "extract" file manager context menu action works too in order to extract the archive. (As said in comment, the
unzip command reports an error with a file renamed with a
zip extension, so renaming to
zip is not the proper choice in itself, but it works with archive managers like