local FIRST_FIELD
             FIRST_FIELD=$(echo "${APT_LINE}" | cut -d' ' -f1)
             if [ "${FIRST_FIELD}" = "${FINISH_LINE}" ]; then
-                printf '%s' "${OUR_NEWLINE}"
+                echo -n "${OUR_NEWLINE}"
                 local EXIT_CODE
                 EXIT_CODE=$(echo "${APT_LINE}" | cut -d' ' -f2)
                 if [ "${EXIT_CODE}" != "0" ]; then
         local IFS
         IFS=$(printf '\n\r')
         for LINE in ${apt_digested_SEDS}; do
-            I=$((1 + "$I")) 
+            I=$((1 + $I))
             if   [ "$I" -eq 1 ]; then
                 PREFIX="${LINE}" 
                 continue
         if [ "${COMPRESSED_ITEM}" = 'IGNORE' ]; then
             continue
         elif [ -z "${COMPRESSED_ITEM}" ]; then
-            printf '%s' "${OUR_NEWLINE}"
+            echo -n "${OUR_NEWLINE}"
             prefixed_msg_no_nl "${APT_LINE}"
             LAST_PREFIX=
         else
             if [ "${PREFIX}" != "${LAST_PREFIX}" ]; then
-                printf '%s' "${OUR_NEWLINE}"
+                echo -n "${OUR_NEWLINE}"
                 prefixed_msg_no_nl "# ${PREFIX}"
                 LAST_PREFIX="${PREFIX}"
             fi
 
 #!/usr/bin/env dash
-set -eu
+set -e
 ROOT=$(dirname "$0")
 cd "${ROOT}"
 . lib/abort.sh
 }
 
 # NB: This needs to come before steps potentially overwriting /etc/network/interfaces.
-apt_digested '-q -q install network-manager'
+apt_digested -q -q install network-manager
 if [ "$(nmcli -f TYPE conn | grep -c 'wifi')" = "0" ]; then
     prefixed_msg "Checking for existing wifi config in ${PATH_NETWORK_INTERFACES} …"
     adopt_wifi_connection