cat /etc/systemd/system/fan.service 
[Unit]
Description=Gestion du ventilateur
ConditionPathExists=/home/crust/scripts/fan.sh
after=network.target
 
[Service]
Type=forking
ExecStart=/home/crust/scripts/fan.sh start
TimeoutSec=0
StandardOutput=tty
RemainAfterExit=yes
SysVStartPriority=99
 
[Install]
WantedBy=multi-user.target