diff --git a/elements/baremetal/cleanup.d/99-extract-kernel-and-ramdisk b/elements/baremetal/cleanup.d/99-extract-kernel-and-ramdisk
index 764741b00..a0fc97d6a 100755
--- a/elements/baremetal/cleanup.d/99-extract-kernel-and-ramdisk
+++ b/elements/baremetal/cleanup.d/99-extract-kernel-and-ramdisk
@@ -26,9 +26,9 @@ RAMDISK=
 if [ -f $TARGET_ROOT/etc/redhat-release ]; then
 
     # Prioritize PAE if present
-    KERNEL=$(ls -1rv $BOOTDIR/vmlinuz*  | grep PAE | grep -v debug | head -1)
+    KERNEL=$(ls -1rv $BOOTDIR/vmlinuz*  | grep PAE | grep -v debug | head -1 || echo "")
     if [ ! $KERNEL ]; then
-        KERNEL=$(ls -1rv $BOOTDIR/vmlinuz* | grep -v debug | head -1)
+        KERNEL=$(ls -1rv $BOOTDIR/vmlinuz* | grep -v debug | head -1 || echo "")
         if [ ! $KERNEL ]; then
             echo "No suitable kernel found."
             exit 1
@@ -38,7 +38,7 @@ if [ -f $TARGET_ROOT/etc/redhat-release ]; then
     KERNEL=$(basename $KERNEL)
     KERNEL_VERSION=`echo $KERNEL | sed 's/vmlinuz-//g'`
 
-    RAMDISK=$(basename `ls $BOOTDIR/initramfs-$KERNEL_VERSION.img`)
+    RAMDISK=$(basename `ls $BOOTDIR/initramfs-$KERNEL_VERSION.img` || echo "")
     if [ ! $RAMDISK ]; then
         echo "Can't find an initramfs for the $KERNEL_VERSION version of the kernel."
         exit 1
diff --git a/elements/base/extra-data.d/99-enable-install-types b/elements/base/extra-data.d/99-enable-install-types
index d1e097d94..ee5e66653 100755
--- a/elements/base/extra-data.d/99-enable-install-types
+++ b/elements/base/extra-data.d/99-enable-install-types
@@ -25,7 +25,7 @@ SPECIFIED_ELEMS[0]=""
 
 # List of all env vars to set install types
 PREFIX="DIB_INSTALLTYPE_"
-INSTALL_TYPE_VARS=$(env | grep ^$PREFIX | cut -d'=' -f1)
+INSTALL_TYPE_VARS=$(env | grep ^$PREFIX | cut -d'=' -f1 || echo "")
 
 for _install_type_var in $INSTALL_TYPE_VARS; do
 
diff --git a/elements/cache-url/bin/cache-url b/elements/cache-url/bin/cache-url
index 25ef9a36f..132c2704e 100755
--- a/elements/cache-url/bin/cache-url
+++ b/elements/cache-url/bin/cache-url
@@ -23,6 +23,7 @@ set -e
 
 url=$1
 dest=$2
+time_cond=
 
 mkdir -p $(dirname $dest)
 tmp=$(mktemp $(dirname $dest)/.download.XXXXXXXX)
diff --git a/elements/dib-run-parts/bin/dib-run-parts b/elements/dib-run-parts/bin/dib-run-parts
index 6d965c16c..af5fde934 100755
--- a/elements/dib-run-parts/bin/dib-run-parts
+++ b/elements/dib-run-parts/bin/dib-run-parts
@@ -59,7 +59,7 @@ fi
 # parallelized later
 # Note: -maxdepth 1 ensures only files in the target directory (but not
 # subdirectories) are run, which is the way run-parts behaves.
-targets=$(find $target_dir -maxdepth 1 -xtype f -executable -printf '%f\n' | grep -E "$allowed_regex" | LANG=C sort -n)
+targets=$(find $target_dir -maxdepth 1 -xtype f -executable -printf '%f\n' | grep -E "$allowed_regex" | LANG=C sort -n || echo "")
 
 if [ "$show_list" == "1" ] ; then
   for target in $targets ; do
diff --git a/elements/dkms/post-install.d/99-dkms b/elements/dkms/post-install.d/99-dkms
index 1e3773a6b..53911aac1 100755
--- a/elements/dkms/post-install.d/99-dkms
+++ b/elements/dkms/post-install.d/99-dkms
@@ -3,7 +3,14 @@
 # to ensure we have valid modules build for all.
 
 modules=$(dkms status | tr ',:' ' ' | awk '{ print $1 "/" $2 }')
-kernels=$(ls /usr/src/linux-headers-*-*-* -d | sed -e 's|/usr/src/linux-headers-||')
+kernels=$(ls /usr/src/linux-headers-*-*-* -d | sed -e 's|/usr/src/linux-headers-||' || echo "")
+# NOTE(bnemec): On Fedora, the versions can be found in /usr/src/kernels
+if [ -z "$kernels" ]; then
+  kernels=$(ls /usr/src/kernels/* -d | sed -e 's|/usr/src/kernels/||' || echo "")
+fi
+if [ -z "$kernels" ]; then
+  echo "Warning: No kernel versions found for DKMS"
+fi
 __ARCH=$ARCH
 unset ARCH
 
diff --git a/elements/dpkg/bin/install-packages b/elements/dpkg/bin/install-packages
index d5ce2306f..fb62429b4 100755
--- a/elements/dpkg/bin/install-packages
+++ b/elements/dpkg/bin/install-packages
@@ -21,8 +21,8 @@ set -e
 
 install_deb_packages () {
   DEBIAN_FRONTEND=noninteractive \
-    http_proxy=$http_proxy https_proxy=$https_proxy \
-    no_proxy=$no_proxy \
+    http_proxy=${http_proxy:-} https_proxy=${https_proxy:-} \
+    no_proxy=${no_proxy:-} \
     apt-get --option "Dpkg::Options::=--force-confold" --assume-yes "$@"
 }
 
diff --git a/elements/dpkg/root.d/50-build-with-http-cache b/elements/dpkg/root.d/50-build-with-http-cache
index dc66629f1..28cedd2d5 100755
--- a/elements/dpkg/root.d/50-build-with-http-cache
+++ b/elements/dpkg/root.d/50-build-with-http-cache
@@ -5,7 +5,7 @@ set -e
 [ -n "$TARGET_ROOT" ]
 
 # If we have a network proxy, use it.
-if [ -n "$http_proxy" ] ; then
+if [ -n "${http_proxy:-}" ] ; then
     sudo dd of=$TARGET_ROOT/etc/apt/apt.conf.d/60img-build-proxy << _EOF_
 Acquire::http::Proxy "$http_proxy";
 _EOF_
diff --git a/elements/local-config/pre-install.d/02-proxy-settings b/elements/local-config/pre-install.d/02-proxy-settings
index f4050fdfe..15afdb3f7 100755
--- a/elements/local-config/pre-install.d/02-proxy-settings
+++ b/elements/local-config/pre-install.d/02-proxy-settings
@@ -5,6 +5,12 @@
 set -e
 set -o xtrace
 
+have_apt=
+have_yum=
+have_zypper=
+http_proxy=${http_proxy:-""}
+https_proxy=${https_proxy:-""}
+
 if [ -d /etc/apt ] ; then
   have_apt=1
 fi
diff --git a/elements/ramdisk/extra-data.d/scripts/init b/elements/ramdisk/extra-data.d/scripts/init
index b58168d02..a947e27d4 100755
--- a/elements/ramdisk/extra-data.d/scripts/init
+++ b/elements/ramdisk/extra-data.d/scripts/init
@@ -60,7 +60,7 @@ else
 fi
 
 # udev versions 176 and newer require a different on-disk setup
-UDEVD_VERSION=$($UDEVD --version)
+UDEVD_VERSION=$(udevadm --version)
 
 if [ "$UDEVD_VERSION" != "" -a $UDEVD_VERSION -gt 175 ]; then
     echo "Using new-style udevd setup"
diff --git a/elements/ramdisk/init.d/02-start-network b/elements/ramdisk/init.d/02-start-network
index c5878bf78..995e6c61e 100644
--- a/elements/ramdisk/init.d/02-start-network
+++ b/elements/ramdisk/init.d/02-start-network
@@ -15,16 +15,19 @@ fi
 readonly BOOT_INTERFACE
 
 ifconfig lo 127.0.0.1 up
-ifconfig "$BOOT_INTERFACE" up
-if [ $? -ne 0 ]; then
+rv=0
+ifconfig "$BOOT_INTERFACE" up || rv=1
+if [ rv -ne 0 ]; then
 	sleep 10
-	ifconfig "$BOOT_INTERFACE" up
+	rv=0
+	ifconfig "$BOOT_INTERFACE" up || rv=1
 	if [ $? -ne 0 ]; then
 		err_msg "Failed to ifconfig up $BOOT_INTERFACE"
 		troubleshoot
 	fi
 fi
 ifconfig "$BOOT_INTERFACE" "$BOOT_IP_ADDRESS" netmask "$BOOT_NETMASK"
+route del default || true
 route add default gw $BOOT_GATEWAY
 
 echo "pinging to boot server $BOOT_SERVER"
diff --git a/elements/ramdisk/post-install.d/01-ensure-binaries b/elements/ramdisk/post-install.d/01-ensure-binaries
index 128013d37..c6297b673 100755
--- a/elements/ramdisk/post-install.d/01-ensure-binaries
+++ b/elements/ramdisk/post-install.d/01-ensure-binaries
@@ -17,6 +17,8 @@ if [ ! -d $TARGET_DIR ] ; then
   exit 1
 fi
 
+BINARY_DEPS=
+
 for _FILE in $(ls ${TARGET_DIR}/binary-deps.d/) ; do
   _FILE="${TARGET_DIR}/binary-deps.d/${_FILE}"
   if [ -a $_FILE ]; then
diff --git a/elements/ramdisk/post-install.d/99-build-ramdisk b/elements/ramdisk/post-install.d/99-build-ramdisk
index 3aabf7cbc..49110f064 100755
--- a/elements/ramdisk/post-install.d/99-build-ramdisk
+++ b/elements/ramdisk/post-install.d/99-build-ramdisk
@@ -20,6 +20,9 @@ LIB_UDEV=$LIB_UDEV_ROOT/lib/udev
 INIT="$_LIB/scripts/init"
 FUNCTIONS_D="$_LIB/scripts/d"
 BUSYBOX=${BUSYBOX:-$(which busybox)}
+# NOTE(bnemec): IMAGE_ELEMENT is normally set in disk-image-create, but we're
+# not using that to build the image here.
+IMAGE_ELEMENT=
 
 mk_build_dir
 mkdir -p $TMP_BUILD_DIR/mnt
diff --git a/elements/vm/block-device.d/10-partition b/elements/vm/block-device.d/10-partition
index 036063285..10c8dc17f 100755
--- a/elements/vm/block-device.d/10-partition
+++ b/elements/vm/block-device.d/10-partition
@@ -19,6 +19,7 @@ sudo partprobe $IMAGE_BLOCK_DEVICE
 sudo udevadm settle
 
 # If the partition isn't under /dev/loop*p1, create it with kpartx
+DM=
 if [ ! -e "${IMAGE_BLOCK_DEVICE}p1" ]; then
     sudo kpartx -asv $TMP_IMAGE_PATH
     DM=${IMAGE_BLOCK_DEVICE/#\/dev/\/dev\/mapper}
diff --git a/elements/yum/bin/install-packages b/elements/yum/bin/install-packages
index 7a351abec..956cc2353 100755
--- a/elements/yum/bin/install-packages
+++ b/elements/yum/bin/install-packages
@@ -17,6 +17,8 @@
 
 set -e
 
+EXTRA_ARGS=
+
 if [ "$1" = "-u" ] ; then
   yum -y update
   exit 0
diff --git a/lib/common-functions b/lib/common-functions
index 16e1994e8..0e1b67bdd 100644
--- a/lib/common-functions
+++ b/lib/common-functions
@@ -110,7 +110,7 @@ function generate_hooks () {
 # $1 the break point.
 # $2.. what to call if a break is needed
 function check_break () {
-  if echo "$break" | egrep -e "(,|^)$1(,|$)" -q; then
+  if echo "${break:-}" | egrep -e "(,|^)$1(,|$)" -q; then
     echo "Starting debug shell. Exit to resume building." >&2
     echo At stage $1 >&2
     shift