Assuming you made a bit of a typo with your regexp, any of these should work as you want:

grep -oE '/dev/loop[0-9]+'
awk 'match($0, /\/dev\/loop[0-9]+/) { print substr($0, RSTART, RLENGTH) }'
sed -r 's%.*(/dev/loop[0-9]+).*%\1%'

AWK one is a bit cursed as you can see. Such ways of manipulating text is not exactly it’s strong suite.

As a hopeless Gentoo user myself, I must warn you: it’s very addictive and it will become your one and only hobby, whether you like it or not.

For the love of all that’s saint, can we please stop recommending Manjaro to people, especially newbies?

It’s not really a preference thing, Manjaro team did plenty of questionable stuff with it, as in DDoSing AUR, mind you, twice, or letting their server certificates expire, also more than once.

It also routinely shows more stability issues that led to the infamous “I swear to god, if it’s Manjaro again…” in AUR discussions. Apart from AUR problems, they also shipped alpha quality things to their users, like this and this.

I’ve used Manjaro myself for around a month. If you are treating it as a regular Arch installation, you will break it.

If you want something up to date, but more stable than Arch, just use Fedora. If you insist on it being Arch-based, use something like CachyOS. Or you can read the wiki and install Arch itself. Arch is a DIY distro, after all.

That’s a completely different tool, though, no? I just do this for determining when I need to clean up:

df -hx tmpfs

Gives me enough information for this purpose and, again, does not require any additional software, df is part of coreutils.

Yea, I love du -hd 1 | sort -h when cleaning up. I absolutely love that I don’t need any extra software to quickly locate whatever takes up space. I can do this on any machine without installing anything extra.