Hard disks have three states: empty, dead, and full. You can reach a full disk faster than expected due to carelessly hoarded data, much like in a kitchen junk drawer. Error messages logged once a millisecond, such as .xsession-errors, can also quickly fill up a logfile causing even large hard disks to overflow overnight.

If your disk is filling up, you first need to identify the cause, specifically which directories or files are hogging the most space. Plasma and Gnome have graphical tools such as Filelight, GdMap, or Baobab, which display the utilization level. However, these tools are very slow, making them unsuitable for network servers or full hard disks, because a graphical user interface will often fail to launch if the disk utilization level exceeds 95 percent.

Instead, you need a terminal-based solution. Linux on-board tools, such as du or df can show disk utilization, but they are not necessarily renowned for their clarity. For example, you can use the du command in Listing 1 to display the 20 largest directories in home but in a pretty awkward way. Another option is ncdu [1], an Ncurses-based tool available in the archives of all major distributions, which I covered in an earlier issue [2]. While ncdu does a fantastic job, it lacks speed during indexing.

[...]