df -h
df -hi
# shell startup file
alias lsfs='pydf -ha | grep -P /dev/md | grep -v /var/lib/lxd'
# lsfs
/dev/md4 1804G 1111G 601G 61.6 [####..] /
/dev/md4 1804G 1111G 601G 61.6 [####..] /david-favor
#!/bin/sh
#set -x
T=$(mktemp)
mount >$T
find . -mount -mindepth 1 -maxdepth 1 -type d |
while read i
do
grep -E -q "on $(readlink -f "$i") " $T || du -sx "$i"
done | sort -n
rm $T
which I have named vss, as below
vss>vss.out
cat vss.out
The largest directories are at the bottom, so are left on the screen. Run it in /, then in the largest few identified directories. ls -lSr (sort by size) if you don't see big directories in the next level down.
EDIT 1 : Well this was a bit quirky...there is an old module for Webmin called Disk Usage ...install the 1.2 version and you should see it under Others...somehow this should be the END but the module by default only queries the /tmp folder when the issue is to get the whole disk...so if you look carefully you will see a faded cog for settings...hit it and change to / let it calculate/collect and that's all...all the info in a single click
EDIT 2: it's added in the side notification panel and you have a quick overiew or click to have the whole picture