In December 2021, a modified backup script deleted 77 TB of research data from Kyoto University’s supercomputer. This article rebuilds the failure chain with live demos: how bash reads a running script from an open file descriptor, what an inode is, why cp and mv treat it differently, and how one pair of missing quotes turns a log cleanup into a mass deletion.

This article explains why using rm on Linux doesn’t truly erase files and how tools like extundelete can recover them. It introduces shred as a safer alternative for secure deletion and contrasts behavior on ext4 with modern copy-on-write filesystems like Btrfs and ZFS.