@terdon what make this '{print $NF}' part?

@nobody context?

That looks like an awk script that will print the last space-separated field of every line in its input.

your command for available linux-images wget -O - packages.ubuntu.com/focal/kernel 2>/dev/null | grep -oP 'Linux kernel image for version \S+' | awk '{print $NF}' | sort | uniq | sort -Vr

Ah, right. Yes, that just print the last field, in this case, the version of the package:

terdon@tpad ~ $ wget -O - packages.ubuntu.com/focal/kernel 2>/dev/null | grep -oP 'Linux kernel image for version \S+'  | head -n1
Linux kernel image for version 5.11.0
terdon@tpad ~ $ wget -O - packages.ubuntu.com/focal/kernel 2>/dev/null | grep -oP 'Linux kernel image for version \S+'  | head -n1 | awk '{print $NF}'
5.11.0

Oh thanks.

you're welcome

This is a special awk variable which holds the number of fields in each line (NF=="number of fields") and is automatically updated for each inputline. So since in awk fields are numbered with the 1st field being $1, the second $2 etc, because NF is the number of fields, it will be 3 if there are three fields. Therefore, {print $NF} prints the last field.

Those are the greatest power of the *nix command line: the ability to chain multiple utilities together to run complex commands.

It does take a little (OK, maybe a lot) of time to learn, but once you've learned them and gotten used to them, it really frees your hands!

I never use a file manager for example. It is always easier for me to do all file operations (copy, rename, move, whatever) from the command line.

but after 3 chained commands my head becomes empty. :D

Yeah, I can understand that. It really gets easier with practice though!

On my debian there is a folder with the for me importance commands. your one is also end up there too