Most of these are not about the Linux kernel, but about distro / personal choice. Android tracks you and doesn’t make you use the command-line a lot. Fedora / Ubuntu (and others?) like to reboot for every little update.

Bookmarked 😜 Mind adding a dark mode?

in [[ there is generally no need for quoting, except the right hand side of an = comparison

in [[, empty strings are falsy, so this also works:

[[ ! $VARIABLE1 && ! $VARIABLE2 ]] && echo "OK"

The variables need a dollar sign: $VARIABLE1

help test shows what -n and -z do.

Never use a && b || c. It is not the same as if a; then b; else c; fi: when a succeeds but b fails, it will run both b and c.

I would not bother with [ unless you absolutely need compatibility with non-bash shells.