Install Clamav After Installation

I am pretty sure time to time, admins may need to install some component after installing HCP. But there is no document or option in hestia. It would be nice to have at least some documentation.

I need to install Clamav. Is this part taken from installer ok to apply. Or any stable way to install it? Because there are some variable below that I can not know.

if [ "$clamd" = 'yes' ]; then
    gpasswd -a clamav mail > /dev/null 2>&1
    gpasswd -a clamav Debian-exim > /dev/null 2>&1
    cp -f $HESTIA_INSTALL_DIR/clamav/clamd.conf /etc/clamav/
    update-rc.d clamav-daemon defaults
    if [ ! -d "/var/run/clamav" ]; then
        mkdir /var/run/clamav
    fi
    chown -R clamav:clamav /var/run/clamav
    if [ -e "/lib/systemd/system/clamav-daemon.service" ]; then
        exec_pre1='ExecStartPre=-/bin/mkdir -p /var/run/clamav'
        exec_pre2='ExecStartPre=-/bin/chown -R clamav:clamav /var/run/clamav'
        sed -i "s|\[Service\]/|[Service]\n$exec_pre1\n$exec_pre2|g" \
            /lib/systemd/system/clamav-daemon.service
        systemctl daemon-reload
    fi
    echo -ne "[ * ] Installing ClamAV anti-virus definitions... "
    /usr/bin/freshclam >> $LOG &
    BACK_PID=$!
    spin_i=1
    while kill -0 $BACK_PID > /dev/null 2>&1 ; do
        printf "\b${spinner:spin_i++%${#spinner}:1}"
        sleep 0.5
    done
    echo
    systemctl start clamav-daemon
    check_result $? "clamav-daemon start failed"
fi