# df -h
show list of partitions mounted [man]
# dpkg-query -W -f='${Installed-Size;10}t${Package}n' | sort -k1,1nshow the used space by installed deb packages, sorting by size (debian, ubuntu and alike) [man]
# du -sh dir1
estimate space used by directory 'dir1' [man]
# du -sk * | sort -rn
show size of the files and directories sorted by size [man]
# ls -lSr |more
show size of the files and directories ordered by size [man]
# rpm -q -a --qf '%10{SIZE}t%{NAME}n' | sort -k1,1nshow the used space by rpm packages installed sorted by size (fedora, redhat and alike) [man]