systemd

for Linux veterans - Why systemd is the future!



Dennis "@the_metalgamer" Fink

29 June 2015

at "Spark-Up: Getting deep!" by C3L

Table of Contents

Terms

systemd - the init system

systemd is a suite of basic building blocks for a Linux system. It provides a system and service manager that runs as PID 1 and starts the rest of the system.

Basic concepts

systemd provides aggressive parallelization capabilities, uses socket and D-Bus activation for starting services, offers on-demand starting of daemons, keeps track of processes using Linux control groups, supports snapshotting and restoring of the system state, maintains mount and automount points and implements an elaborate transactional dependency-based service control logic.

systemd supports SysV and LSB init scripts and works as a replacement for sysvinit.

Unit files

Example

[Unit]
Description=IPv6 Router Advertisement Daemon
After=network.target

[Service]
ExecStart=/usr/bin/radvd --nodaemon --logmethod=stderr

[Install]
WantedBy=multi-user.target

Unit section

Install section

Service files

Service section

Service section

Security options

Security options

Security options

ReadWriteDirectories=

ReadOnlyDirectories=

InaccessibleDirectories=

Security options

PrivateTmp=

PrivateDevices=

PrivateNetwork=

Security options

SystemCallFilter=

SystemCallArchitectures=

Security options

RestrictAddressFamilies=

Sockets

Timers

systemctl

Commands

Commands

Commands

Commands

systemd-cgls & systemd-cgtop

journald

systemd-journald is a system service that collects and stores logging data.

journalctl

udevd

systemd-udevd listens to kernel uevents. For every event, systemd-udevd executes matching instructions specified in udev rules.

hostnamed

systemd-hostnamed is a system service that may be used as a mechanism to change the system's hostname. systemd-hostnamed is automatically activated on request and terminates itself when it is unused.

logind

systemd-logind is a system service that manages user logins.

networkd

systemd-networkd is a system service that manages networks.

networkd

resolved

systemd-resolved is a system service that manages network name resolution. It implements a caching DNS stub resolver and an LLMNR resolver and responder. It also generates /run/systemd/resolve/resolv.conf for compatibility which may be symlinked from /etc/resolv.conf

timedated

systemd-timedated is a systemd service that may be used as a mechanism to change the system clock and timezone, as well as to enable/disable NTP time synchronization.

timesyncd

systemd-timesyncd is a system service that may be used to synchronize the local system clock with a remote Network Time Protocol server.

localed

systemd-localed is a system service that may be used as mechanism to change the system locale settings, as well as the console key mapping and default X11 key mapping.

Future and other things

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