I am running an XFCE flavoured manjaro and am trying to familiarize myself more and more with pacman.
Now I believe to probably have packages which are not actually needed and am looking to understand better whether they are save to remove.
My current example is gnome-icon-theme, which the pamac GUI presents me to be upgradable.
pacman -Qi gnome-icon-theme says "Required By: None". That plus not using gnome makes me believe the package to be obsolete.
I can find a GNOME entry in the graphical >Appearance >Icons though but as it is not highlighted I believe I am not using it (and wouldn’t mind to change whether it was in play)
Only you can decide that - but generally speaking - from a system perspective - yes, it’s safe.
The specific package gnome-icon-theme has been moved to AUR and therefore removed from the repo. The reason is, it has been replaced by Adwaita - so it is most likely not needed.
Even though you may not be using Gnome desktop - gnome is everywhere - XFCE is built using the gnome toolkit - so the statement not using Gnome makes it obsolete - is not always true.
Package gnome-icon-theme was removed from repo and moved to AUR (probably), because I just removed it too day or so ago. It was explicitly installed for one reason or the other, so it won’t show up as an orphan.
But there are a lot of explicitly installed packages with "Required By: None" and you can find them with pacman -Qt
if you are, as me, not 100% secure with pacman … look at the difference between pacman -R gnome-icon-theme vs pacman -Rs gnome-icon-theme
as far as I understand the matter pacman -R (in our little example here) would leave gnome-icon-theme-symbolic (being a dependency of gnome-icon-theme) as an orphan on the system while pacman -Rs also gets rid of it recursively (the -s option meaning recursive).
Not knowing about or using Rs may leave a lot of orphaned packages on your system over time.
$ sudo pacman -Rs gnome-icon-theme
checking dependencies...
Packages (2) gnome-icon-theme-symbolic-3.12.0-6 gnome-icon-theme-3.12.0-7
Total Removed Size: 11,72 MiB
:: Do you want to remove these packages? [Y/n]