vbox clean disk

dd if=/dev/zero of=/var/tmp/bigemptyfile bs=4096k ; rm /var/tmp/bigemptyfile

dd if=/dev/zero of=/var/dummy bs=8126k

VBoxManage.exe modifymedium --compact c:\path\to\thedisk.vdi

VBoxManage modifymedium disk ./NWABAP75101.vdi –compact

sudo du -sh /var/cache/apt

• Show top 10 biggest subdirs in the current dir.

 du -sk * | sort -nr | head -10

• Use File Usage Analyzer (AKA baobab; GNOME based), Filelight or kDirStat (KDE based), to see where the disk space is going visually (ncdu uses a TUI).

• Check if you have old kernels for deletion

 ls -lh /boot

• Cleaning packages

 sudo apt autoremove
 sudo apt autoclean

see list of all installed packages, sorted by size. If you see something big and don't use it - uninstall it

 dpkg-query -W --showformat='${Installed-Size} ${Package}\n' | sort -nr | less

• Clean unused language files with translations (there are tons of them)

 sudo apt install localepurge

• Check content of /var/tmp/

 du -sh /var/tmp/

• Check also

 man deborphan

• Search for big files:

 find / -type f -size +1024k

or

 find / -size +50000  -exec ls -lahg {} \;

• Big installed packages (part of the package: debian-goodies)

 dpigs

or

wajig sizes | tail -30.

• On systemd: Remove the oldest archived journal files until the disk space they use falls below the specified size

 sudo journalctl --vacuum-size 10M

sudo lsblk -o NAME,FSTYPE,SIZE,MOUNTPOINT,LABEL

df -h
sudo parted -ls
sudo lsblk -f
sudo lsblk -m


dd if=/dev/zero of=/var/tmp/bigemptyfile bs=4096k status=progress
rm /var/tmp/bigemptyfile

vboxmanage modifymedium x:\path\to\disk.vdi --compact

https://askubuntu.com/questions/5980/how-do-i-free-up-disk-space