programs we use

System Util

ncdu - command line disk usage analyzer

also lets you delete stuff.

# analyze current working dir, stay in the same filesystem
ncdu -x

Gentoo

emaint - performs package management related system health checks and maintenance

# run this on the thingy that builds binary packages to
# rebuild the metadata index
emaint binhost --fix

eclean - clean up source/binary package cache

# delete source for anything without an ebuild in any repos
eclean-dist

# delete source for anything that isn't installed
eclean-dist -d

# delete binary packages from /usr/portage/packages for anything
# without an ebuild
eclean-pkg

# delete binary packages from /usr/portage/packages for anything
# that isn't installed
eclean-pkg -d