Ubuntu disk usage cleanup

Ref:

  • https://unix.stackexchange.com/questions/130786/can-i-remove-files-in-var-log-journal-and-var-cache-abrt-di-usr
  • https://askubuntu.com/questions/65549/var-cache-apt-archives-occupying-huge-space
sudo apt-get clean
sudo rm -rf /var/log/journal/*