PREIN

/bin/sh

/usr/share/rpm-helper/add-user dhcp $1 dhcpd /dev/null /bin/false

PREUN

/bin/sh

/usr/share/rpm-helper/del-service dhcp $1 dhcpd

POSTIN

/bin/sh

/usr/share/rpm-helper/add-service dhcp $1 dhcpd 
/usr/bin/systemd-tmpfiles --create dhcpd.conf 
# New dhcpd lease file
if [ ! -f /var/lib/dhcpd/dhcpd.leases ]; then
    touch /var/lib/dhcpd/dhcpd.leases
fi