Snaps are applications packaged with all their dependencies to run on all popular Linux distributions from a single build. They update automatically and roll back gracefully. Whether you’re building for desktop, cloud, or the Internet of Things, publishing as a snap will keep users up to date and make system configuration issues less likely, freeing you to code more and debug less. From Ubuntu
Discover installed snaps
Sometimes you can see a lot of loop devices mounted on your linux
An important command which I discovered and use is docker ps --size. Its show what is the size of the container.
[[email protected] ~]$ docker ps --size CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES SIZE dbffabfb478a docker:17.05-dind "dockerd-entrypoin..." 4 weeks ago Up About a minute 2375/tcp docker1705-dind 10.2MB (virtual 110MB)
On this case, you can see the column size which show 10.2MB (virtual 110MB). Compare with the output of docker images:
[[email protected] ~]$ docker images REPOSITORY TAG IMAGE ID CREATED SIZE docker 17.05-dind b547d892dffa 4 weeks ago 99.6MB
We discover the virtual size is the sum of image size + 10.2MB (this space was used creating a file with dd command).
The slice (or slices) that compose the base image is not used for each instance that you run with docker, only the the difference will be stored on the hard disk. In this case represented by 10.2MB.