See a running log of all system messages:

1journalctl -f

Or just one user:

1journalctl --user -f

Or just one unit (sshd):

1journalctl -f -u sshd

Find errors since November

1journalctl --since=2018-11-01 --grep="EXT4-fs error"

Limit size to 2G.

1journalctl --vacuum-size=2G

Log the fact that you've installed your …

Basics

A service can consist of two files - the .sh script to run, and the .service file which describes its run conditions.

The .service file goes in /etc/systemd/system. The scripts themselves might be best placed in $HOME/.local/bin.

Example - tracker.service

1[Unit]
2Description=Tracker
3
4[Service]
5Type=simple
6 …

1systemctl list-units

1sudo systemctl status mpd

1sudo systemctl daemon-reload

1sudo systemctl taskd.service start

1sudo systemctl status taskd.service

1sudo systemd-analyze

1sudo systemd-analyze blame