systemd.admins
From: https://0pointer.net/blog/projects/systemd-docs.html 


There is also a series of deeply technical articles for Linux sysadmins by
Lennart Poettering, the designer and primary developer of systemd. These
articles were written between April 2010 and September 2011, but they are
just as relevant now as they were then. Much of everything else good that
has been written about systemd and its ecosystem is based on these papers.

Contents

    Introduction
    Support status
    System Init Daemon
    Switching init systems
        Switch to upstart for a single boot
        Permanent switch back to upstart
    High-level startup concept
    Job vs. unit keywords
            Shell scripts
            Automatic starting
        Invalid configurations
    Override Files
    Behavioral differences (aka Gotchas)
    Commands
    Example Services
        Example Upstart Service
        Example Systemd service
    Outstanding Work
    Common Idioms
        Service that specifies shell meta-characters
        Service that does not fork (runs in foreground)
        Do not run service if no daemon configuration file created
        /etc/default files which enable/disable jobs
        Start a service when a file is created
        Start a service when a D-Bus name is acquired
    Well-known Sequence Points
    Environment Differences
    Common Problems
        How to identify which init system you are currently booting with
        Why don't some commands (like grep) work in /lib/systemd/system ?
    Debugging
        Boot Time
            Common Setup
            Upstart
            systemd
                Starting a rescue shell
        From a running system
            Upstart
    Debian Packaging
    Further Information