Recently started using arch linux, seems like really cool distro.

it uses “pacman” as package manager.
Following is some use full commands.

pacman queries the local package database with the -Q flag.

$ pacman -Q --help

and queries the sync databases with the -S flag.

$ pacman -S --help

pacman can search for packages in the database, searching both in packages' names and descriptions.

$ pacman -Ss package

To search for already installed packages.

$ pacman -Qs package

To display extensive information about a given package.

$ pacman -Si package

for locally installed packages.

$ pacman -Qi package

To retrieve a list of the files installed by a package.

$ pacman -Ql package

One can also query the database to know which package a file on the file system belongs to.

$ pacman -Qo /path/to/a/file

To list all packages no longer required as dependencies (orphans).

$ pacman -Qdt