Pacman
Remove a package and its deps not required by any other packages:
pacman -Rs package_name
Remove a package and its deps and all the packages that depend on the target package:
pacman -Rsc package_name
Search for already installed packages:
pacman -Qs string1 string2 ...
Search for package file names in remote packages:
pacman -Fs string1 string2 ...
Show extensive information about a given package:
pacman -Si package_name
Show information about a local package:
pacman -Qi package_name
pacman -Qii package_name (also list of backup files and their modification states)
Which remote package a file belongs to
pacman -Fo /path/to/file
All packages no longer required (orphans)
pacman -Qdt
List dependency tree
pactree package_name
Who needs a package
pactree -r package_name
Clean the package cache
pacman -Sc
Pacman fails signature verification
If encounter this while makepkg:
==> Verifying source file signatures with gpg...
linux-4.6.tar ... FAILED (unknown public key 79BE3E4300411886)
patch-4.6.3 ... FAILED (unknown public key 38DBBDC86092693E)
Because makepkg uses gpg and is unaware of the pacman’s keyring. Do this:
# run as root
gpg --list-keys
Receive the keys using pacman-key -r KEY_ID first, and then, add keyring /etc/pacman.d/gnupg/pubring.gpg to the end of ~/.gnupg/gpg.conf