/lib/systemd/system/jekyll.service:
[Unit]
Description=JekyllServer
After=syslog.target network.target
[Service]
Type=simple
ExecStart=/usr/local/bin/jekyll serve --incremental --host YOUR_IP --port PORTNUMBER --source /path/to/page
ExecReload=/usr/bin/kill -HUP $MAINPID
[Install]
WantedBy=multi-user.target