Note by Hung Nguyen

  Introduction Systemd logs all  Linux  messages from the  kernel  and system processes. The journalctl command enables viewing and editing the systemd logs, making it a powerful tool for service and process debugging. This guide shows how to read, control, and maintain systemd logs using journalctl through examples. Prerequisites Access to the command line/terminal window. A text editor (such as  nano ) to edit the config file. A user with sudo privileges (see how to  add a user to sudoers ). What Is Systemd? Systemd is a Linux service and system manager. While users do not invoke systemd directly, the manager contains many tools and daemons to run individually for various system processes. One of the most powerful systemd functionalities is the logging features. Systemd provides a centralized solution for logging all  kernel  and user processes through logs known as  journals . The  journald  daemon collects all the messages the system outputs and then creates journals, regardless of