The correct file to edit in order to permanently change the hostname on a Linux system is /etc/hostname. This file contains the system's hostname, which is read at boot time and sets the system's hostname for the duration of the session. Other options provided are close, but they serve different purposes: /etc/hosts is used for static IP to hostname mappings, and while /etc/hostname.conf and /etc/sysconfig/hostname look like they might be related to hostname configuration, they are not standard files for setting the hostname on most Linux distributions.