[1705][root@raspberrypi:/home/pi]# ll /etc/systemd/system/lte.service
-rwxr-xr-x 1 root root 139 Apr 30 17:04 /etc/systemd/system/lte.service

[1705][root@raspberrypi:/home/pi]# cat /etc/systemd/system/lte.service
[unit]
Description=Telenor LTE

[Service]
ExecStart=/usr/local/bin/check_connection.pl

[Install]
WantedBy=multi-user.target

[1705][root@raspberrypi:/home/pi]# systemctl enable lte.service
Synchronizing state for lte.service with sysvinit using update-rc.d...
Executing /usr/sbin/update-rc.d lte defaults
insserv: script lte is not an executable regular file, skipped!
insserv: Script create_ssh_tunnel is broken: incomplete LSB comment.
insserv: missing valid name for `Provides:' please add.
Executing /usr/sbin/update-rc.d lte enable
update-rc.d: error: no runlevel symlinks to modify, aborting!