Keep size of virtual Filesystem small

shrink-filesystem.md

Old Way:

dd if=/dev/zero of=zero.small.file bs=1024 count=102400
dd if=/dev/zero of=zero.file bs=1024
rm zero.small.file
sync ; sleep 60 ; sync
rm zero.file

in a windows vm you can use sdelete:
sdelete.exe -z c::

New Way:

crontab -e
0 12 * * *   /sbin/fstrim -a -v -m 16m