Updating the updater itself
sudo tlmgr update --self
Updating the updater itself and all the packages
sudo tlmgr update --self --all
Updating the TeXLive distribution
sudo tlmgr -gui
You can check if a package is installed by using the locate command.
Sometimes, a package is installed but the symlink to it in system directories is
missing. You can update the symlinks through the tlmgr program.