Systemd

systemd is a Linux initialization system and service manager introduced in 2010 and adopted by default in RHEL 7.0 (2014), that includes features like:

• On-demand starting of daemons
• Inhibitor locks which allows to block or delay system sleep and shutdown requests from the user
• Mount and automount point maintenance (systemd-mount, systemd-umount )
• Snapshot support
• Processes tracking using Linux control groups (systemd-cglssystemd-cgtop)
• Logging daemon, see journalctl and systemd-cat
• Resource management

Configuration files

• /etc/systemd/logind.conf
• /etc/systemd/system.conf
• /etc/systemd/resolved.conf

• /etc/systemd/system/

Systemd components of daemons and binaries:

• systemd: systemctl
• systemd-journald: journalctl
• systemd-logind: loginctl
• systemd-networkd: networkctl, netplan
• systemd-timesyncd
• systemd-resolved: systemd-resolve, hostnamectl
• systemd-udevd
• systemd-nspawn

/lib/systemd/systemd-fsck

/lib/systemd/system/

Activities

• Read systemd for Administrators: http://0pointer.de/blog/projects/resources.html
• Read systemd v228 local root exploit https://lwn.net/Articles/712367/

Related

• systemd-tmpfiles --create
• OpenRC
• machinectl
• hostnamectl
• systemd 250
• systemd socket activation (Ubuntu 22.10)

See also

• Systemd: systemctl, systemd-journald, journalctl systemd-cat, systemd-logind, systemd-networkd:networkctl, systemd-timesyncd, systemd-resolved, systemd-udevd , Systemd-logind: loginctl, hostnamectl, udevadm, systemd-run, portablectl, systemd-nspawn, systemd resource management, Timer (systemd), systemd logs, /etc/systemd/, systemd services, systemd-mount, /run/systemd/, .service, /usr/lib/systemd/, /usr/lib/systemd/system/, /usr/lib/systemd/system/systemd-resolved.service, /lib/systemd/, machinectl, systemd-oomd, systemd-analyze
• macOS: launctl
• systemd, daemontools, runit and https://en.wikipedia.org/wiki/Process_supervision
• systemd, runsv
• cron, crontab, systemctl list-timers, anacron, Kubernetes scheduler, Systemd services, CronJobsStack, cron.schedule, crontab -l, 0x004b, at, /etc/cron.deny, /etc/cron.allow, /etc/crontab, /var/spool/cron/crontabs/
• elogind
• init (inittab), supervisor, systemd, upstart, service, chkconfig, OpenRC, s6-svstat

https://www.freedesktop.org/wiki/Software/systemd/inhibit/

http://manpages.ubuntu.com/manpages/bionic/man1/systemd-inhibit.1.html

https://www.freedesktop.org/software/systemd/man/systemd.mount.html

https://wiki.ubuntu.com/DebuggingSystemd

https://wiki.ubuntu.com/DebuggingSystemd