systemd

journalctl
http://www.panticz.de/journalctl

Services

# list services
service  --status-all
systemctl list-units --type service --state running,failed

# enable service
systemctl enable service_name
sudo systemctl enable --now service_name

# disable service
systemctl disable service_name

systemctl status mariadb.service

journalctl -f
systemd-analyze verify 

systemd-analyze critical-chain
systemctl list-units
systemctl list-unit-files --type=service

# override / edit job
systemctl edit cron.service
# systemd/system/cron.service.d/override.conf

# list reboots
journalctl --list-boots

# list dhcp client logs
sudo journalctl --since "7 days ago" -u dnsmasq-dhcp
sudo journalctl --since "7 days ago" | grep -i dhcp

# suspend system
sleep 10m && systemctl suspend

# Fix slow SSH login
systemctl restart systemd-logind

# restart user service
systemctl --user restart pulseaudio.service

# list all service names
systemctl list-units -t service --state active --no-pager --full --plain --no-legend "ceph*" | awk '/ceph-/ {print $1}'

Example
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# test
[Unit]
After=getty.target

[Service]
TTYPath=/dev/tty1

# test
journalctl -xn
systemctl list-unit-files --all

Disable systemd-resolved service

systemd