Force non interactive, and only attempt to move systemctl and apt if exist

Dockerfile.template

@@ -4,6 +4,7 @@ LABEL image="{{ pihole.name }}:{{ pihole.os }}_{{ pihole.arch }}"
 LABEL maintainer="{{ pihole.maintainer }}"
 LABEL url="https://www.github.com/diginc/docker-pi-hole"
 
+ARG DEBIAN_FRONTED=noninteractive
 ENV TAG {{ pihole.os }}
 ENV ARCH {{ pihole.arch }}
 ENV PATH /opt/pihole:${PATH}

install.sh

@@ -8,9 +8,9 @@ export USE_DEVELOPMENT_BRANCHES=false
 #     Make pihole scripts fail searching for `systemctl`,
 # which fails pretty miserably in docker compared to `service`
 # For more info see docker/docker issue #7459
-mv "$(which systemctl)" /bin/no_systemctl && \
+which systemctl && mv "$(which systemctl)" /bin/no_systemctl
 # debconf-apt-progress seems to hang so get rid of it too
-mv "$(which debconf-apt-progress)" /bin/no_debconf-apt-progress
+which which debconf-apt-progress && mv "$(which debconf-apt-progress)" /bin/no_debconf-apt-progress
 
 # Get the install functions
 wget -O "$PIHOLE_INSTALL" https://raw.githubusercontent.com/pi-hole/pi-hole/${CORE_TAG}/automated%20install/basic-install.sh