systemd

systemd

What is systemd?

• A system manager daemon that has replaced UNIX init in a lot of linux distributions.
• It has been controversial because systemd violates the UNIX principle of "Make each program do one thing well. To do a new job, build afresh rather than complicate old programs by adding new "features."
• PID 1

Parts of systemd

• networkd
• journald
  • collects log messages from the kernel and services
  • system messages are stored in /run
  • rsyslog can store these messages in log files, or forward them to a syslog server
  • the systemd journal configuration file is at /etc/systemd/journald.conf
  • journalctl --disk-usage shows how much diskspace journald is using
• logind

systemd Commands

• systemctl lists all running services
• journalctl lists all log entries with the oldest first *
• systemd-analyze shows system boot performance stats
• hostnamectl controls the system hostname
  • To change the hostname, hostnamectl set-hostname <name_here>
• timedatectl controls the system time and date
  • timedatectl set-time <time>

Resources

• Chapter 2 The Unix and Linux System Administration Handbook, Fifth Edition
• Linux Academy: Mastering Systemd