A collection with useful details about startup scripts for various Operating Systems.

Content of /etc/systemd/kamailio.service“

[Unit]
Description=Kamailio SIP Server
Documentation=man:kamailio(8) http://www.kamailio.org/
After=syslog.target network-online.target

[Service]
Type=forking
User=kamailio
Environment=SHM_SIZE=64
Environment=PKG_SIZE=8
ExecStartPre=/usr/sbin/kamailio -c
ExecStart=/usr/sbin/kamailio -m $SHM_SIZE -M $PKG_SIZE \
 -P /run/kamailio/kamailio.pid
ExecStopPost=/usr/bin/rm -f /run/kamailio/kamailio.pid
PIDFile=/run/kamailio/kamailio.pid
Restart=on-failure
RestartSec=30

[Install]
WantedBy=multi-user.target

Content of /etc/tmpfiles.d/kamailio.conf:

d /run/kamailio 0750 kamailio kamailio

systemctl daemon-reload
systemctl enable kamailio
systemctl start kamailio