pacman -Syy
S: sync.
y: refresh the packets database.
y: force to refresh the local databases (even if it is up to date).
When pacman performs an operation that requires synchronization (like installing a package), it uses the servers listed in /etc/pacman.d/mirrorlist, trying them from top to bottom.
If your downloads are slow, it is a good idea to regenerate your mirror list.
pacman -S <package_name>: to install a package. pacman will automatically handle and install any necessary dependencies. You can install multiple packages at once by listing them with spaces in between.
pacman -R <package_name>: to uninstall a package.
R: remove.pacman -Ss <keyword>: to search for a package if you do not know the exact name.
pacman -Syu: it synchronizes your package databases and then upgrades all out-of-date packages on the system.
u: update.Two weeks between upgrades is a good amount of time.
pacman -Qdt: to find orphan packages. These are packages that were installed as dependencies but are no longer required by any installed package.
Q: query.
d: skips dependency checks.
t: limit the results to orphan packages.