top file size

find -type f -exec du -Sh {} + | sort -rh | head -n 5
ls -l --block-size=K
ls -l --block-size=G

du -h /var/log/*.*
df -h

To find the largest 10 files:q
find . -type f -print0 | xargs -0 du | sort -n | tail -10 | cut -f2 | xargs -I{} du -sh {} | grep -v "Permission denied" > largest_files.txt && more largest_files.txt

To find the largest 10 directories:
find . -type d -print0 | xargs -0 du | sort -n | tail -10 | cut -f2 | xargs -I{} du -sh {} | grep -v "Permission denied" > largest_directories.txt && more largest_directories.txt