Tell `df` not to report on virtual filesystems such as `squashfs` (used
by `snapd` and always at 100%), `tmpfs` (memory-only) and `devtmpfs`
(used by `udev`)
The `ss` program is now the official replacement for `netstat` which
is deprecated in most Linux distributions. Also replace the messy sed
rules which do not work on all versions with a clean command-line that
just displays the key information that does **not** change on every
command run (e.g. PID) resulting in false positives.
