diff --git a/board/bananapim1/cpinitramfs.sh b/board/bananapim1/cpinitramfs.sh
index 7c5af3f0e4..6b79ac324c 100755
--- a/board/bananapim1/cpinitramfs.sh
+++ b/board/bananapim1/cpinitramfs.sh
@@ -1,4 +1,4 @@
 #!/bin/bash
 
-cp $IMG_DIR/rootfs.cpio.uboot $BOARD_DIR/uInitrd
+cp ${IMG_DIR}/rootfs.cpio.uboot ${BOARD_DIR}/uInitrd
 
diff --git a/board/bananapim1/mkimage.sh b/board/bananapim1/mkimage.sh
index 21fc43f036..7592c0dc83 100755
--- a/board/bananapim1/mkimage.sh
+++ b/board/bananapim1/mkimage.sh
@@ -1,12 +1,12 @@
 #!/bin/bash -e
 
 BOARD_DIR=$(dirname $0)
-COMMON_DIR=$BOARD_DIR/../common
+COMMON_DIR=${BOARD_DIR}/../common
 
-export BOARD=$(basename $BOARD_DIR)
-export IMG_DIR=$BOARD_DIR/../../output/$BOARD/images/
-export UBOOT_BIN=$IMG_DIR/u-boot-sunxi-with-spl.bin
+export BOARD=$(basename ${BOARD_DIR})
+export IMG_DIR=${BOARD_DIR}/../../output/${BOARD}/images/
+export UBOOT_BIN=${IMG_DIR}/u-boot-sunxi-with-spl.bin
 export UBOOT_SEEK=16
 
-$COMMON_DIR/mkimage.sh
+${COMMON_DIR}/mkimage.sh
 
diff --git a/board/bananapim1/postscript.sh b/board/bananapim1/postscript.sh
index 57228f0501..41c58a2070 100755
--- a/board/bananapim1/postscript.sh
+++ b/board/bananapim1/postscript.sh
@@ -2,13 +2,13 @@
 
 set -e
 
-UBOOT_HOST_DIR=$TARGET/../build/host-uboot-tools-*
+UBOOT_HOST_DIR=${TARGET}/../build/host-uboot-tools-*
 
-cp $IMG_DIR/uImage $BOOT_DIR
-cp $IMG_DIR/sun7i-a20-bananapi.dtb $BOOT_DIR
+cp ${IMG_DIR}/uImage ${BOOT_DIR}
+cp ${IMG_DIR}/sun7i-a20-bananapi.dtb ${BOOT_DIR}
 
-$UBOOT_HOST_DIR/tools/mkimage -C none -A arm -T script -d $BOARD_DIR/boot.cmd $BOOT_DIR/boot.scr
-$UBOOT_HOST_DIR/tools/mkimage -C none -A arm -T script -d $BOARD_DIR/boot-fwupdater.cmd $BOOT_DIR/boot-fwupdater.scr
+${UBOOT_HOST_DIR}/tools/mkimage -C none -A arm -T script -d ${BOARD_DIR}/boot.cmd ${BOOT_DIR}/boot.scr
+${UBOOT_HOST_DIR}/tools/mkimage -C none -A arm -T script -d ${BOARD_DIR}/boot-fwupdater.cmd ${BOOT_DIR}/boot-fwupdater.scr
 
-cp $BOARD_DIR/uInitrd $BOOT_DIR
+cp ${BOARD_DIR}/uInitrd ${BOOT_DIR}
 
diff --git a/board/common/cleanups.sh b/board/common/cleanups.sh
index f92796c54f..2a8e6925cb 100755
--- a/board/common/cleanups.sh
+++ b/board/common/cleanups.sh
@@ -1,211 +1,211 @@
 #!/bin/sh
 
-if [ -z "$TARGET" ]; then
+if [ -z "${TARGET}" ]; then
     echo "this script must be invoked from postscript.sh"
     exit 1
 fi
 
-find $TARGET -name '.empty' | xargs -r rm
+find ${TARGET} -name '.empty' | xargs -r rm
 
 # /etc stuff
-rm -rf $TARGET/etc/network/
-rm -rf $TARGET/etc/dhcp/
-rm -rf $TARGET/etc/ssh/
-rm -rf $TARGET/etc/rc_keymaps/
-rm -rf $TARGET/etc/default/
-rm -rf $TARGET/etc/ctdb/
-rm -rf $TARGET/etc/sudoers.d/
-rm -rf $TARGET/etc/ssl/man
-rm -rf $TARGET/etc/ssl/misc
-rm -rf $TARGET/etc/ssl/private
-rm -rf $TARGET/etc/logrotate.d
+rm -rf ${TARGET}/etc/network/
+rm -rf ${TARGET}/etc/dhcp/
+rm -rf ${TARGET}/etc/ssh/
+rm -rf ${TARGET}/etc/rc_keymaps/
+rm -rf ${TARGET}/etc/default/
+rm -rf ${TARGET}/etc/ctdb/
+rm -rf ${TARGET}/etc/sudoers.d/
+rm -rf ${TARGET}/etc/ssl/man
+rm -rf ${TARGET}/etc/ssl/misc
+rm -rf ${TARGET}/etc/ssl/private
+rm -rf ${TARGET}/etc/logrotate.d
 
-rm -f $TARGET/etc/rc_maps.cfg
-rm -f $TARGET/etc/udev/hwdb.d/20-pci-vendor-model.hwdb
-rm -f $TARGET/etc/hostname
-rm -f $TARGET/etc/os-release
-rm -f $TARGET/etc/hostapd.conf
+rm -f ${TARGET}/etc/rc_maps.cfg
+rm -f ${TARGET}/etc/udev/hwdb.d/20-pci-vendor-model.hwdb
+rm -f ${TARGET}/etc/hostname
+rm -f ${TARGET}/etc/os-release
+rm -f ${TARGET}/etc/hostapd.conf
 
 # /usr/share stuff
-rm -rf $TARGET/usr/share/bash-completion/
-rm -rf $TARGET/usr/share/locale/*
-rm -rf $TARGET/usr/share/ffmpeg/
-rm -rf $TARGET/usr/share/perl5/
-rm -rf $TARGET/usr/share/common-lisp/
+rm -rf ${TARGET}/usr/share/bash-completion/
+rm -rf ${TARGET}/usr/share/locale/*
+rm -rf ${TARGET}/usr/share/ffmpeg/
+rm -rf ${TARGET}/usr/share/perl5/
+rm -rf ${TARGET}/usr/share/common-lisp/
 
 # various binaries
-rm -f $TARGET/bin/more
-rm -f $TARGET/bin/wdctl
-rm -f $TARGET/usr/sbin/readprofile
-rm -f $TARGET/sbin/nologin
-rm -f $TARGET/bin/mountpoint
-rm -f $TARGET/sbin/ldattach
-rm -f $TARGET/usr/sbin/ldattach
-rm -f $TARGET/sbin/slattach
-rm -f $TARGET/sbin/plipconfig
-rm -f $TARGET/sbin/fstrim
-rm -f $TARGET/usr/sbin/rtcwake
-rm -f $TARGET/bin/lsblk
-rm -f $TARGET/usr/bin/col
-rm -f $TARGET/sbin/fdformat
-rm -f $TARGET/sbin/ctrlaltdel
-rm -f $TARGET/bin/findmnt
-rm -f $TARGET/usr/bin/colcrt
-rm -f $TARGET/sbin/fsfreeze
-rm -f $TARGET/usr/bin/colrm
-rm -f $TARGET/usr/sbin/addpart
-rm -f $TARGET/sbin/blkdiscard
-rm -f $TARGET/usr/sbin/delpart
-rm -f $TARGET/usr/bin/column
-rm -f $TARGET/sbin/swapon
-rm -f $TARGET/usr/sbin/resizepart
-rm -f $TARGET/usr/bin/hexdump
-rm -f $TARGET/sbin/swapoff
-rm -f $TARGET/usr/bin/rev
-rm -f $TARGET/sbin/chcpu
-rm -f $TARGET/usr/bin/tailf
-rm -f $TARGET/usr/bin/pg
-rm -f $TARGET/sbin/blkid
-rm -f $TARGET/usr/bin/ul
-rm -f $TARGET/sbin/findfs
-rm -f $TARGET/sbin/wipefs
-rm -f $TARGET/usr/bin/script
-rm -f $TARGET/usr/bin/scriptreplay
-rm -f $TARGET/sbin/fsck.minix
-rm -f $TARGET/sbin/mkfs.minix
-rm -f $TARGET/usr/bin/setterm
-rm -f $TARGET/usr/bin/flock
-rm -f $TARGET/sbin/mkfs
-rm -f $TARGET/usr/bin/ipcmk
-rm -f $TARGET/sbin/mkfs.bfs
-rm -f $TARGET/usr/bin/ipcrm
-rm -f $TARGET/usr/bin/ipcs
-rm -f $TARGET/sbin/mkswap
-rm -f $TARGET/usr/bin/renice
-rm -f $TARGET/sbin/swaplabel
-rm -f $TARGET/usr/bin/setsid
-rm -f $TARGET/sbin/blockdev
-rm -f $TARGET/usr/bin/cytune
-rm -f $TARGET/usr/bin/setarch
-rm -f $TARGET/sbin/sfdisk
-rm -f $TARGET/usr/bin/prlimit
-rm -f $TARGET/sbin/cfdisk
-rm -f $TARGET/usr/bin/lscpu
-rm -f $TARGET/usr/bin/unshare
-rm -f $TARGET/usr/bin/nsenter
-rm -f $TARGET/usr/bin/cal
-rm -f $TARGET/usr/bin/look
-rm -f $TARGET/usr/bin/mcookie
-rm -f $TARGET/usr/bin/namei
-rm -f $TARGET/usr/bin/whereis
-rm -f $TARGET/usr/bin/lslocks
-rm -f $TARGET/usr/bin/uuidgen
-rm -f $TARGET/usr/bin/getopt
-rm -f $TARGET/bin/isosize
-rm -f $TARGET/usr/sbin/fdformat
-rm -f $TARGET/usr/bin/linux32
-rm -f $TARGET/usr/bin/linux64
-rm -f $TARGET/usr/bin/uname26
-rm -f $TARGET/bin/zcat
-rm -f $TARGET/bin/zcmp
-rm -f $TARGET/bin/zdiff
-rm -f $TARGET/bin/zegrep
-rm -f $TARGET/bin/zfgrep
-rm -f $TARGET/bin/zforce
-rm -f $TARGET/bin/zgrep
-rm -f $TARGET/bin/zless
-rm -f $TARGET/bin/zmore
-rm -f $TARGET/bin/znew
-rm -f $TARGET/bin/gzexe
-rm -f $TARGET/bin/uncompress
-rm -f $TARGET/usr/bin/slogin
-rm -f $TARGET/usr/bin/ssh-keyscan
-rm -f $TARGET/usr/bin/ssh-add
-rm -f $TARGET/usr/bin/ssh-agent
-rm -f $TARGET/usr/bin/xmllint
+rm -f ${TARGET}/bin/more
+rm -f ${TARGET}/bin/wdctl
+rm -f ${TARGET}/usr/sbin/readprofile
+rm -f ${TARGET}/sbin/nologin
+rm -f ${TARGET}/bin/mountpoint
+rm -f ${TARGET}/sbin/ldattach
+rm -f ${TARGET}/usr/sbin/ldattach
+rm -f ${TARGET}/sbin/slattach
+rm -f ${TARGET}/sbin/plipconfig
+rm -f ${TARGET}/sbin/fstrim
+rm -f ${TARGET}/usr/sbin/rtcwake
+rm -f ${TARGET}/bin/lsblk
+rm -f ${TARGET}/usr/bin/col
+rm -f ${TARGET}/sbin/fdformat
+rm -f ${TARGET}/sbin/ctrlaltdel
+rm -f ${TARGET}/bin/findmnt
+rm -f ${TARGET}/usr/bin/colcrt
+rm -f ${TARGET}/sbin/fsfreeze
+rm -f ${TARGET}/usr/bin/colrm
+rm -f ${TARGET}/usr/sbin/addpart
+rm -f ${TARGET}/sbin/blkdiscard
+rm -f ${TARGET}/usr/sbin/delpart
+rm -f ${TARGET}/usr/bin/column
+rm -f ${TARGET}/sbin/swapon
+rm -f ${TARGET}/usr/sbin/resizepart
+rm -f ${TARGET}/usr/bin/hexdump
+rm -f ${TARGET}/sbin/swapoff
+rm -f ${TARGET}/usr/bin/rev
+rm -f ${TARGET}/sbin/chcpu
+rm -f ${TARGET}/usr/bin/tailf
+rm -f ${TARGET}/usr/bin/pg
+rm -f ${TARGET}/sbin/blkid
+rm -f ${TARGET}/usr/bin/ul
+rm -f ${TARGET}/sbin/findfs
+rm -f ${TARGET}/sbin/wipefs
+rm -f ${TARGET}/usr/bin/script
+rm -f ${TARGET}/usr/bin/scriptreplay
+rm -f ${TARGET}/sbin/fsck.minix
+rm -f ${TARGET}/sbin/mkfs.minix
+rm -f ${TARGET}/usr/bin/setterm
+rm -f ${TARGET}/usr/bin/flock
+rm -f ${TARGET}/sbin/mkfs
+rm -f ${TARGET}/usr/bin/ipcmk
+rm -f ${TARGET}/sbin/mkfs.bfs
+rm -f ${TARGET}/usr/bin/ipcrm
+rm -f ${TARGET}/usr/bin/ipcs
+rm -f ${TARGET}/sbin/mkswap
+rm -f ${TARGET}/usr/bin/renice
+rm -f ${TARGET}/sbin/swaplabel
+rm -f ${TARGET}/usr/bin/setsid
+rm -f ${TARGET}/sbin/blockdev
+rm -f ${TARGET}/usr/bin/cytune
+rm -f ${TARGET}/usr/bin/setarch
+rm -f ${TARGET}/sbin/sfdisk
+rm -f ${TARGET}/usr/bin/prlimit
+rm -f ${TARGET}/sbin/cfdisk
+rm -f ${TARGET}/usr/bin/lscpu
+rm -f ${TARGET}/usr/bin/unshare
+rm -f ${TARGET}/usr/bin/nsenter
+rm -f ${TARGET}/usr/bin/cal
+rm -f ${TARGET}/usr/bin/look
+rm -f ${TARGET}/usr/bin/mcookie
+rm -f ${TARGET}/usr/bin/namei
+rm -f ${TARGET}/usr/bin/whereis
+rm -f ${TARGET}/usr/bin/lslocks
+rm -f ${TARGET}/usr/bin/uuidgen
+rm -f ${TARGET}/usr/bin/getopt
+rm -f ${TARGET}/bin/isosize
+rm -f ${TARGET}/usr/sbin/fdformat
+rm -f ${TARGET}/usr/bin/linux32
+rm -f ${TARGET}/usr/bin/linux64
+rm -f ${TARGET}/usr/bin/uname26
+rm -f ${TARGET}/bin/zcat
+rm -f ${TARGET}/bin/zcmp
+rm -f ${TARGET}/bin/zdiff
+rm -f ${TARGET}/bin/zegrep
+rm -f ${TARGET}/bin/zfgrep
+rm -f ${TARGET}/bin/zforce
+rm -f ${TARGET}/bin/zgrep
+rm -f ${TARGET}/bin/zless
+rm -f ${TARGET}/bin/zmore
+rm -f ${TARGET}/bin/znew
+rm -f ${TARGET}/bin/gzexe
+rm -f ${TARGET}/bin/uncompress
+rm -f ${TARGET}/usr/bin/slogin
+rm -f ${TARGET}/usr/bin/ssh-keyscan
+rm -f ${TARGET}/usr/bin/ssh-add
+rm -f ${TARGET}/usr/bin/ssh-agent
+rm -f ${TARGET}/usr/bin/xmllint
 
-rm -f $TARGET/usr/libexec/ssh-keysign
-rm -f $TARGET/usr/libexec/ssh-pkcs11-helper
-rm -f $TARGET/usr/libexec/rmt
+rm -f ${TARGET}/usr/libexec/ssh-keysign
+rm -f ${TARGET}/usr/libexec/ssh-pkcs11-helper
+rm -f ${TARGET}/usr/libexec/rmt
 
 # samba4 unneeded stuff
-rm -f $TARGET/usr/bin/cifsdd
-rm -f $TARGET/usr/bin/containers_*
-rm -f $TARGET/usr/bin/ctdb*
-rm -f $TARGET/usr/bin/dbwrap_tool
-rm -f $TARGET/usr/bin/eventlogadm
-rm -f $TARGET/usr/bin/event_rpcgen.py
-rm -f $TARGET/usr/bin/gentest
-rm -f $TARGET/usr/bin/ldb*
-rm -f $TARGET/usr/bin/locktest
-rm -f $TARGET/usr/bin/ltdbtool
-rm -f $TARGET/usr/bin/masktest
-rm -f $TARGET/usr/bin/ndrdump
-rm -f $TARGET/usr/bin/net
-rm -f $TARGET/usr/bin/ntdb*
-rm -f $TARGET/usr/bin/ntlm_auth
-rm -f $TARGET/usr/bin/oLschema2ldif
-rm -f $TARGET/usr/bin/onnode
-rm -f $TARGET/usr/bin/pdbedit
-rm -f $TARGET/usr/bin/pidl
-rm -f $TARGET/usr/bin/ping_pong
-rm -f $TARGET/usr/bin/profiles
-rm -f $TARGET/usr/bin/reg*
-rm -f $TARGET/usr/bin/rpcclient
-rm -f $TARGET/usr/bin/samba-regedit
-rm -f $TARGET/usr/bin/sharesec
-rm -f $TARGET/usr/bin/smbcacls
-rm -f $TARGET/usr/bin/smbcontrol
-rm -f $TARGET/usr/bin/smbcquotas
-rm -f $TARGET/usr/bin/smbget
-rm -f $TARGET/usr/bin/smbspool
-rm -f $TARGET/usr/bin/smbstatus
-rm -f $TARGET/usr/bin/smbta-util
-rm -f $TARGET/usr/bin/smbtar
-rm -f $TARGET/usr/bin/smbtree
-rm -f $TARGET/usr/bin/smnotify
-rm -f $TARGET/usr/bin/tdb*
-rm -f $TARGET/usr/bin/testparm
-rm -f $TARGET/usr/bin/wbinfo
-rm -f $TARGET/usr/sbin/winbindd
-rm -rf $TARGET/usr/share/ctdb
+rm -f ${TARGET}/usr/bin/cifsdd
+rm -f ${TARGET}/usr/bin/containers_*
+rm -f ${TARGET}/usr/bin/ctdb*
+rm -f ${TARGET}/usr/bin/dbwrap_tool
+rm -f ${TARGET}/usr/bin/eventlogadm
+rm -f ${TARGET}/usr/bin/event_rpcgen.py
+rm -f ${TARGET}/usr/bin/gentest
+rm -f ${TARGET}/usr/bin/ldb*
+rm -f ${TARGET}/usr/bin/locktest
+rm -f ${TARGET}/usr/bin/ltdbtool
+rm -f ${TARGET}/usr/bin/masktest
+rm -f ${TARGET}/usr/bin/ndrdump
+rm -f ${TARGET}/usr/bin/net
+rm -f ${TARGET}/usr/bin/ntdb*
+rm -f ${TARGET}/usr/bin/ntlm_auth
+rm -f ${TARGET}/usr/bin/oLschema2ldif
+rm -f ${TARGET}/usr/bin/onnode
+rm -f ${TARGET}/usr/bin/pdbedit
+rm -f ${TARGET}/usr/bin/pidl
+rm -f ${TARGET}/usr/bin/ping_pong
+rm -f ${TARGET}/usr/bin/profiles
+rm -f ${TARGET}/usr/bin/reg*
+rm -f ${TARGET}/usr/bin/rpcclient
+rm -f ${TARGET}/usr/bin/samba-regedit
+rm -f ${TARGET}/usr/bin/sharesec
+rm -f ${TARGET}/usr/bin/smbcacls
+rm -f ${TARGET}/usr/bin/smbcontrol
+rm -f ${TARGET}/usr/bin/smbcquotas
+rm -f ${TARGET}/usr/bin/smbget
+rm -f ${TARGET}/usr/bin/smbspool
+rm -f ${TARGET}/usr/bin/smbstatus
+rm -f ${TARGET}/usr/bin/smbta-util
+rm -f ${TARGET}/usr/bin/smbtar
+rm -f ${TARGET}/usr/bin/smbtree
+rm -f ${TARGET}/usr/bin/smnotify
+rm -f ${TARGET}/usr/bin/tdb*
+rm -f ${TARGET}/usr/bin/testparm
+rm -f ${TARGET}/usr/bin/wbinfo
+rm -f ${TARGET}/usr/sbin/winbindd
+rm -rf ${TARGET}/usr/share/ctdb
 
 # useless mongodb binaries
-rm -f $TARGET/usr/bin/mongos
-rm -f $TARGET/usr/bin/mongoperf
+rm -f ${TARGET}/usr/bin/mongos
+rm -f ${TARGET}/usr/bin/mongoperf
 
 # v4l-utils
-rm -f $TARGET/usr/bin/cec-compliance
-rm -f $TARGET/usr/bin/cec-ctl
-rm -f $TARGET/usr/bin/cec-follower
-rm -f $TARGET/usr/bin/dvb-fe-tool
-rm -f $TARGET/usr/bin/dvb-format-convert
-rm -f $TARGET/usr/bin/dvbv5-daemon
-rm -f $TARGET/usr/bin/dvbv5-scan
-rm -f $TARGET/usr/bin/dvbv5-zap
-rm -f $TARGET/usr/bin/media-ctl
-rm -f $TARGET/usr/bin/rds-ctl
-rm -f $TARGET/usr/bin/v4l2-compliance
+rm -f ${TARGET}/usr/bin/cec-compliance
+rm -f ${TARGET}/usr/bin/cec-ctl
+rm -f ${TARGET}/usr/bin/cec-follower
+rm -f ${TARGET}/usr/bin/dvb-fe-tool
+rm -f ${TARGET}/usr/bin/dvb-format-convert
+rm -f ${TARGET}/usr/bin/dvbv5-daemon
+rm -f ${TARGET}/usr/bin/dvbv5-scan
+rm -f ${TARGET}/usr/bin/dvbv5-zap
+rm -f ${TARGET}/usr/bin/media-ctl
+rm -f ${TARGET}/usr/bin/rds-ctl
+rm -f ${TARGET}/usr/bin/v4l2-compliance
 
 # unused python folders
-rm -rf $TARGET/usr/lib/python2.7/site-packages/samba/
-rm -rf $TARGET/usr/lib/python2.7/ensurepip/
-rm -rf $TARGET/usr/lib/python2.7/config/
-rm -rf $TARGET/usr/lib/python2.7/unittest/
+rm -rf ${TARGET}/usr/lib/python2.7/site-packages/samba/
+rm -rf ${TARGET}/usr/lib/python2.7/ensurepip/
+rm -rf ${TARGET}/usr/lib/python2.7/config/
+rm -rf ${TARGET}/usr/lib/python2.7/unittest/
 
 # buildroot default startup scripts
-rm -f $TARGET/etc/init.d/S01logging
-rm -f $TARGET/etc/init.d/S10udev
-rm -f $TARGET/etc/init.d/S15watchdog
-rm -f $TARGET/etc/init.d/S20urandom
-rm -f $TARGET/etc/init.d/S49ntp
-rm -f $TARGET/etc/init.d/S50sshd
-rm -f $TARGET/etc/init.d/S50proftpd
-rm -f $TARGET/etc/init.d/S80dhcp-relay
-rm -f $TARGET/etc/init.d/S80dhcp-server
-rm -f $TARGET/etc/init.d/S80dnsmasq
-rm -f $TARGET/etc/init.d/S91smb
+rm -f ${TARGET}/etc/init.d/S01logging
+rm -f ${TARGET}/etc/init.d/S10udev
+rm -f ${TARGET}/etc/init.d/S15watchdog
+rm -f ${TARGET}/etc/init.d/S20urandom
+rm -f ${TARGET}/etc/init.d/S49ntp
+rm -f ${TARGET}/etc/init.d/S50sshd
+rm -f ${TARGET}/etc/init.d/S50proftpd
+rm -f ${TARGET}/etc/init.d/S80dhcp-relay
+rm -f ${TARGET}/etc/init.d/S80dhcp-server
+rm -f ${TARGET}/etc/init.d/S80dnsmasq
+rm -f ${TARGET}/etc/init.d/S91smb
 
 # other unwanted dirs
-rm -rf $TARGET/data/*
-rm -rf $TARGET/run
+rm -rf ${TARGET}/data/*
+rm -rf ${TARGET}/run
diff --git a/board/common/mkimage.sh b/board/common/mkimage.sh
index a681280f63..68c37e3fbd 100755
--- a/board/common/mkimage.sh
+++ b/board/common/mkimage.sh
@@ -1,11 +1,11 @@
 #!/bin/bash -e
 
-if [ -z "$IMG_DIR" ] || [ -z "$BOARD" ]; then
+if [ -z "${IMG_DIR}" ] || [ -z "${BOARD}" ]; then
     echo "this script must be invoked from board specific mkimage.sh"
     exit 1
 fi
 
-test "root" != "$USER" && exec sudo -E $0 "$@"
+test "root" != "${USER}" && exec sudo -E $0 "$@"
 
 function msg() {
     echo " * $1"
@@ -13,115 +13,115 @@ function msg() {
 
 BOOT_START=${BOOT_START:-1}  # MB
 
-BOOT_SRC=$IMG_DIR/boot
-BOOT=$IMG_DIR/.boot
-BOOT_IMG=$IMG_DIR/boot.img
+BOOT_SRC=${IMG_DIR}/boot
+BOOT=${IMG_DIR}/.boot
+BOOT_IMG=${IMG_DIR}/boot.img
 BOOT_SIZE="30"  # MB - reserved up to 100 MB
 
 ROOT_START="100"  # MB
-ROOT_SRC=$IMG_DIR/rootfs.tar
-ROOT=$IMG_DIR/.root
-ROOT_IMG=$IMG_DIR/root.img
-ROOT_SIZE="180"  # MB
+ROOT_SRC=${IMG_DIR}/rootfs.tar
+ROOT=${IMG_DIR}/.root
+ROOT_IMG=${IMG_DIR}/root.img
+ROOT_SIZE="200"  # MB
 
 GUARD_SIZE="10"  # MB
 DISK_SIZE=$((ROOT_START + ROOT_SIZE + GUARD_SIZE))
 
-COMMON_DIR=$(cd $IMG_DIR/../../../board/common; pwd)
-OS_NAME=$(source $COMMON_DIR/overlay/etc/version && echo $os_short_name)
+COMMON_DIR=$(cd ${IMG_DIR}/../../../board/common; pwd)
+OS_NAME=$(source ${COMMON_DIR}/overlay/etc/version && echo ${OS_SHORT_NAME})
 
 # boot filesystem
 msg "creating boot loop device"
-dd if=/dev/zero of=$BOOT_IMG bs=1M count=$BOOT_SIZE
-loop_dev=$(losetup -f --show $BOOT_IMG)
+dd if=/dev/zero of=${BOOT_IMG} bs=1M count=${BOOT_SIZE}
+loop_dev=$(losetup -f --show ${BOOT_IMG})
 
 msg "creating boot filesystem"
-mkfs.vfat -F16 $loop_dev
+mkfs.vfat -F16 ${loop_dev}
 
 msg "mounting boot loop device"
-mkdir -p $BOOT
-mount -o loop $loop_dev $BOOT
+mkdir -p ${BOOT}
+mount -o loop ${loop_dev} ${BOOT}
 
 msg "copying boot filesystem contents"
-cp -r $BOOT_SRC/* $BOOT
+cp -r ${BOOT_SRC}/* ${BOOT}
 sync
 
 msg "unmounting boot filesystem"
-umount $BOOT
+umount ${BOOT}
 
-msg "destroying boot loop device ($loop_dev)"
-losetup -d $loop_dev
+msg "destroying boot loop device (${loop_dev})"
+losetup -d ${loop_dev}
 sync
 
 # root filesystem
 msg "creating root loop device"
-dd if=/dev/zero of=$ROOT_IMG bs=1M count=$ROOT_SIZE
-loop_dev=$(losetup -f --show $ROOT_IMG)
+dd if=/dev/zero of=${ROOT_IMG} bs=1M count=${ROOT_SIZE}
+loop_dev=$(losetup -f --show ${ROOT_IMG})
 
 msg "creating root filesystem"
-mkfs.ext4 $loop_dev
-tune2fs -O^has_journal $loop_dev
+mkfs.ext4 ${loop_dev}
+tune2fs -O^has_journal ${loop_dev}
 
 msg "mounting root loop device"
-mkdir -p $ROOT
-mount -o loop $loop_dev $ROOT
+mkdir -p ${ROOT}
+mount -o loop ${loop_dev} ${ROOT}
 
 msg "copying root filesystem contents"
-tar -xpsf $ROOT_SRC -C $ROOT
+tar -xpsf ${ROOT_SRC} -C ${ROOT}
 
 # set internal OS name, prefix and version according to env variables
-if [ -f $ROOT/etc/version ]; then
-    if [ -n "$THINGOS_NAME" ]; then
-        msg "setting OS name to $THINGOS_NAME"
-        sed -ri "s/os_name=\".*\"/os_name=\"$THINGOS_NAME\"/" $ROOT/etc/version
+if [ -f ${ROOT}/etc/version ]; then
+    if [ -n "${THINGOS_NAME}" ]; then
+        msg "setting OS name to ${THINGOS_NAME}"
+        sed -ri "s/OS_NAME=\".*\"/OS_NAME=\"${THINGOS_NAME}\"/" ${ROOT}/etc/version
     fi
-    if [ -n "$THINGOS_SHORT_NAME" ]; then
-        msg "setting OS short name to $THINGOS_SHORT_NAME"
-        sed -ri "s/os_short_name=\".*\"/os_short_name=\"$THINGOS_SHORT_NAME\"/" $ROOT/etc/version
+    if [ -n "${THINGOS_SHORT_NAME}" ]; then
+        msg "setting OS short name to ${THINGOS_SHORT_NAME}"
+        sed -ri "s/OS_SHORT_NAME=\".*\"/OS_SHORT_NAME=\"${THINGOS_SHORT_NAME}\"/" ${ROOT}/etc/version
     fi
-    if [ -n "$THINGOS_PREFIX" ]; then
-        msg "setting OS prefix to $THINGOS_PREFIX"
-        sed -ri "s/os_prefix=\".*\"/os_prefix=\"$THINGOS_PREFIX\"/" $ROOT/etc/version
+    if [ -n "${THINGOS_PREFIX}" ]; then
+        msg "setting OS prefix to ${THINGOS_PREFIX}"
+        sed -ri "s/OS_PREFIX=\".*\"/OS_PREFIX=\"${THINGOS_PREFIX}\"/" ${ROOT}/etc/version
     fi
-    if [ -n "$THINGOS_VERSION" ]; then
-        msg "setting OS version to $THINGOS_VERSION"
-        sed -ri "s/os_version=\".*\"/os_version=\"$THINGOS_VERSION\"/" $ROOT/etc/version
+    if [ -n "${THINGOS_VERSION}" ]; then
+        msg "setting OS version to ${THINGOS_VERSION}"
+        sed -ri "s/OS_VERSION=\".*\"/OS_VERSION=\"${THINGOS_VERSION}\"/" ${ROOT}/etc/version
     fi
 fi
 
 msg "unmounting root filesystem"
-umount $ROOT
+umount ${ROOT}
 
-msg "destroying root loop device ($loop_dev)"
-losetup -d $loop_dev
+msg "destroying root loop device (${loop_dev})"
+losetup -d ${loop_dev}
 sync
 
-DISK_IMG=$IMG_DIR/disk.img
-BOOT_IMG=$IMG_DIR/boot.img
-ROOT_IMG=$IMG_DIR/root.img
+DISK_IMG=${IMG_DIR}/disk.img
+BOOT_IMG=${IMG_DIR}/boot.img
+ROOT_IMG=${IMG_DIR}/root.img
 
-if ! [ -r $BOOT_IMG ]; then
+if ! [ -r ${BOOT_IMG} ]; then
     echo "boot image missing"
     exit -1
 fi
 
-if ! [ -r $ROOT_IMG ]; then
+if ! [ -r ${ROOT_IMG} ]; then
     echo "root image missing"
     exit -1
 fi
 
 # disk image
 msg "creating disk loop device"
-dd if=/dev/zero of=$DISK_IMG bs=1M count=$DISK_SIZE
-if [ -n "$UBOOT_BIN" ] && [ -n "$UBOOT_SEEK" ]; then
+dd if=/dev/zero of=${DISK_IMG} bs=1M count=${DISK_SIZE}
+if [ -n "${UBOOT_BIN}" ] && [ -n "${UBOOT_SEEK}" ]; then
     msg "copying u-boot image"
-    dd conv=notrunc if=$UBOOT_BIN of=$DISK_IMG bs=512 seek=$UBOOT_SEEK
+    dd conv=notrunc if=${UBOOT_BIN} of=${DISK_IMG} bs=512 seek=${UBOOT_SEEK}
 fi
-loop_dev=$(losetup -f --show $DISK_IMG)
+loop_dev=$(losetup -f --show ${DISK_IMG})
 
 msg "partitioning disk"
 set +e
-fdisk -u=sectors $loop_dev <<END
+fdisk -u=sectors ${loop_dev} <<END
 o
 n
 p
@@ -145,36 +145,36 @@ set -e
 sync
 
 msg "reading partition offsets"
-boot_offs=$(fdisk -u=sectors -l $loop_dev | grep -E 'loop([[:digit:]])+p1' | tr -d '*' | tr -s ' ' | cut -d ' ' -f 2)
-root_offs=$(fdisk -u=sectors -l $loop_dev | grep -E 'loop([[:digit:]])+p2' | tr -d '*' | tr -s ' ' | cut -d ' ' -f 2)
+boot_offs=$(fdisk -u=sectors -l ${loop_dev} | grep -E 'loop([[:digit:]])+p1' | tr -d '*' | tr -s ' ' | cut -d ' ' -f 2)
+root_offs=$(fdisk -u=sectors -l ${loop_dev} | grep -E 'loop([[:digit:]])+p2' | tr -d '*' | tr -s ' ' | cut -d ' ' -f 2)
 
-msg "destroying disk loop device ($loop_dev)"
-losetup -d $loop_dev
+msg "destroying disk loop device (${loop_dev})"
+losetup -d ${loop_dev}
 
 msg "creating boot loop device"
-loop_dev=$(losetup -f --show -o $(($boot_offs * 512)) $DISK_IMG)
+loop_dev=$(losetup -f --show -o $((${boot_offs} * 512)) ${DISK_IMG})
 
 msg "copying boot image"
-dd if=$BOOT_IMG of=$loop_dev
+dd if=${BOOT_IMG} of=${loop_dev}
 sync
 
-msg "destroying boot loop device ($loop_dev)"
-losetup -d $loop_dev
+msg "destroying boot loop device (${loop_dev})"
+losetup -d ${loop_dev}
 
 msg "creating root loop device"
-loop_dev=$(losetup -f --show -o $(($root_offs * 512)) $DISK_IMG)
+loop_dev=$(losetup -f --show -o $((${root_offs} * 512)) ${DISK_IMG})
 sync
 
 msg "copying root image"
-dd if=$ROOT_IMG of=$loop_dev
+dd if=${ROOT_IMG} of=${loop_dev}
 sync
 
-msg "destroying root loop device ($loop_dev)"
-losetup -d $loop_dev
+msg "destroying root loop device (${loop_dev})"
+losetup -d ${loop_dev}
 sync
 
-mv $DISK_IMG $(dirname $DISK_IMG)/$OS_NAME-$BOARD.img
-DISK_IMG=$(dirname $DISK_IMG)/$OS_NAME-$BOARD.img
+mv ${DISK_IMG} $(dirname ${DISK_IMG})/${OS_NAME}-${BOARD}.img
+DISK_IMG=$(dirname ${DISK_IMG})/${OS_NAME}-${BOARD}.img
 
-msg "$(realpath "$DISK_IMG") is ready"
+msg "$(realpath "${DISK_IMG}") is ready"
 
diff --git a/board/common/overlay-initramfs/init b/board/common/overlay-initramfs/init
index 7b953cba28..5869745d88 100755
--- a/board/common/overlay-initramfs/init
+++ b/board/common/overlay-initramfs/init
@@ -25,20 +25,20 @@ fi
 msg "Waiting for sdcard"
 count=0
 while true; do
-    if [ $count -ge $DISK_TIMEOUT ]; then
+    if [ ${count} -ge ${DISK_TIMEOUT} ]; then
         break
     fi
-    if [ -b $ROOT_DEV ]; then
+    if [ -b ${ROOT_DEV} ]; then
         break
     fi
-    count=$(($count + 1))
+    count=$((${count} + 1))
     sleep 1
 done
 
-msg "Disk device is $DISK_DEV"
-msg "Boot device is $BOOT_DEV"
-msg "Root device is $ROOT_DEV"
-msg "Data device is $DATA_DEV"
+msg "Disk device is ${DISK_DEV}"
+msg "Boot device is ${BOOT_DEV}"
+msg "Root device is ${ROOT_DEV}"
+msg "Data device is ${DATA_DEV}"
 
 FW_DIR=/data/.fwupdate
 FW_FILE=firmware.img.gz
@@ -74,41 +74,41 @@ if [ -x /prepare_initramfs ]; then
 fi
 
 msg "Mounting boot partition"
-mount $BOOT_DEV /boot
+mount ${BOOT_DEV} /boot
 
 msg "Mounting data partition"
-mount $DATA_DEV /data
+mount ${DATA_DEV} /data
 
-if ! [ -r $FW_DIR/$FW_FILE_EXTR ]; then
-    if [ -r $LEGACY_FW_DIR/$LEGACY_FW_FILE_EXTR ]; then
+if ! [ -r ${FW_DIR}/${FW_FILE_EXTR} ]; then
+    if [ -r ${LEGACY_FW_DIR}/${LEGACY_FW_FILE_EXTR} ]; then
         msg "Detected legacy firmware path"
-        mkdir -p $FW_DIR
-        mv $LEGACY_FW_DIR/$LEGACY_FW_FILE_EXTR $FW_DIR/$FW_FILE_EXTR
+        mkdir -p ${FW_DIR}
+        mv ${LEGACY_FW_DIR}/${LEGACY_FW_FILE_EXTR} ${FW_DIR}/${FW_FILE_EXTR}
         
         msg "Computing root partition info"
-        root_start=$(fdisk -l $FW_DIR/$FW_FILE_EXTR | grep ${FW_FILE_EXTR}2 | tr -s ' ' | cut -d ' ' -f 4)
-        root_start=$(($root_start / 2048))
-        root_size=$(fdisk -l $FW_DIR/$FW_FILE_EXTR | grep ${FW_FILE_EXTR}2 | tr -s ' ' | cut -d ' ' -f 6)
-        root_size=$(($root_size / 2048))
+        root_start=$(fdisk -l ${FW_DIR}/${FW_FILE_EXTR} | grep ${FW_FILE_EXTR}2 | tr -s ' ' | cut -d ' ' -f 4)
+        root_start=$((${root_start} / 2048))
+        root_size=$(fdisk -l ${FW_DIR}/${FW_FILE_EXTR} | grep ${FW_FILE_EXTR}2 | tr -s ' ' | cut -d ' ' -f 6)
+        root_size=$((${root_size} / 2048))
         
-        echo $root_start $root_size > $FW_DIR/$ROOT_INFO_FILE
+        echo ${root_start} ${root_size} > ${FW_DIR}/${ROOT_INFO_FILE}
     else
         msg "No firmware found, aborting"
         exit 1
     fi
 fi
 
-if ! [ -r $FW_DIR/$ROOT_INFO_FILE ]; then
+if ! [ -r ${FW_DIR}/${ROOT_INFO_FILE} ]; then
     msg "No root partition info, aborting"
     exit 1
 fi
 
 msg "Copying root image"
-root_start=$(cat $FW_DIR/$ROOT_INFO_FILE | cut -d ' ' -f 1)
-root_size=$(cat $FW_DIR/$ROOT_INFO_FILE | cut -d ' ' -f 2)
+root_start=$(cat ${FW_DIR}/${ROOT_INFO_FILE} | cut -d ' ' -f 1)
+root_size=$(cat ${FW_DIR}/${ROOT_INFO_FILE} | cut -d ' ' -f 2)
 
-dd if=$FW_DIR/$FW_FILE_EXTR skip=$root_start of=$ROOT_DEV bs=1048576 count=$root_size || exit 1
+dd if=${FW_DIR}/${FW_FILE_EXTR} skip=${root_start} of=${ROOT_DEV} bs=1048576 count=${root_size} || exit 1
 
 msg "Cleaning up"
-rm -rf $FW_DIR
+rm -rf ${FW_DIR}
 
diff --git a/board/common/overlay/etc/init.d/S00datapart b/board/common/overlay/etc/init.d/S00datapart
index f8b2747c07..b1f25768eb 100755
--- a/board/common/overlay/etc/init.d/S00datapart
+++ b/board/common/overlay/etc/init.d/S00datapart
@@ -1,26 +1,26 @@
 #!/bin/bash
 
-test -n "$os_version" || source /etc/init.d/base
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 case "$1" in
     start)
         msg_begin "Detecting disk device"
         root_dev=$(cat /proc/cmdline | grep -oE 'root=[/a-z0-9]+' | cut -d '=' -f 2)
-        if [[ "$root_dev" =~ ^([/a-z0-9]+)(p[0-9])$ ]]; then  # e.g. /dev/mmcblk0p2
+        if [[ "${root_dev}" =~ ^([/a-z0-9]+)(p[0-9])$ ]]; then  # e.g. /dev/mmcblk0p2
             disk_dev=${BASH_REMATCH[1]}
             boot_dev=${disk_dev}p1
             data_dev=${disk_dev}p3
-        elif [[ "$root_dev" =~ ^([/a-z0-9]+)([0-9])$ ]]; then  # e.g. /dev/sdc2
+        elif [[ "${root_dev}" =~ ^([/a-z0-9]+)([0-9])$ ]]; then  # e.g. /dev/sdc2
             disk_dev=${BASH_REMATCH[1]}
             boot_dev=${disk_dev}1
             data_dev=${disk_dev}3
         else
-            msg_fail "unknown ($root_dev)"
+            msg_fail "unknown (${root_dev})"
             exit 1
         fi
-        msg_done "$disk_dev"
+        msg_done "${disk_dev}"
 
-        test -b $data_dev && exit 0
+        test -b ${data_dev} && exit 0
 
         msg_begin "Creating data partition"
         data_start=$((1024 * 2048)) # up to 1024MB reserved for boot + root
@@ -29,12 +29,12 @@ case "$1" in
             3
             ${data_start}
             \n
-            w" | /sbin/fdisk $disk_dev &>/dev/null
-        partx -a $disk_dev &>/dev/null
-        test -b $data_dev && msg_done || msg_fail
+            w" | /sbin/fdisk ${disk_dev} &>/dev/null
+        partx -a ${disk_dev} &>/dev/null
+        test -b ${data_dev} && msg_done || msg_fail
 
         msg_begin "Formatting data partition"
-        mkfs.ext4 -q $data_dev
+        mkfs.ext4 -q ${data_dev}
         test $? == 0 && msg_done || msg_fail
 
         msg_begin "Mounting data partition"
diff --git a/board/common/overlay/etc/init.d/S01mountall b/board/common/overlay/etc/init.d/S01mountall
index 71065f714d..cafa43c0b3 100755
--- a/board/common/overlay/etc/init.d/S01mountall
+++ b/board/common/overlay/etc/init.d/S01mountall
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-test -n "$os_version" || source /etc/init.d/base
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 mount_fs() {
     msg_begin "Mounting filesystems"
@@ -22,8 +22,8 @@ remount_rw() {
 }
 
 mk_tty_login() {
-    test -z "$os_tty_login" && os_tty_login=tty1
-    ln -sf /dev/$os_tty_login /dev/ttylogin
+    test -z "${OS_TTY_LOGIN}" && OS_TTY_LOGIN=tty1
+    ln -sf /dev/${OS_TTY_LOGIN} /dev/ttylogin
 }
 
 case "$1" in
@@ -31,8 +31,8 @@ case "$1" in
         mount_fs
 
         # we need to source conf again, now that /data is available
-        test -n "$os_debug" || source /etc/init.d/conf
-        test "$os_debug" == "true" && remount_rw
+        source /etc/init.d/os_conf
+        test "${OS_DEBUG}" == "true" && remount_rw
         mk_tty_login
         ;;
 
diff --git a/board/common/overlay/etc/init.d/S02modules b/board/common/overlay/etc/init.d/S02modules
index 685f63a5fb..118781b47a 100755
--- a/board/common/overlay/etc/init.d/S02modules
+++ b/board/common/overlay/etc/init.d/S02modules
@@ -1,20 +1,26 @@
 #!/bin/bash
 
-sys_modules_file="/etc/modules"
-modules_file="/data/etc/modules"
+SYS_MODULES_FILE="/etc/modules"
+BOOT_MODULES_FILE="/boot/modules"
+MODULES_FILE="/data/etc/modules"
 
-test -n "$os_version" || source /etc/init.d/base
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 case "$1" in
     start)
         msg_begin "Loading kernel modules"
 
-        if [[ -r $sys_modules_file ]]; then
-            cat $sys_modules_file | while read line; do test -n "$line" && /sbin/modprobe $line &>/dev/null; done
+        if [[ -r ${SYS_MODULES_FILE} ]]; then
+            cat ${SYS_MODULES_FILE} | while read line; do test -n "${line}" && /sbin/modprobe ${line} &>/dev/null; done
         fi
 
-        if [[ -r $modules_file ]]; then
-            cat $modules_file | while read line; do test -n "$line" && /sbin/modprobe $line &>/dev/null; done
+        if [[ -r ${BOOT_MODULES_FILE} ]]; then
+            cat ${BOOT_MODULES_FILE} | while read line; do test -n "${line}" && /sbin/modprobe ${line} &>/dev/null; done
+        fi
+
+        if [[ -r ${MODULES_FILE} ]]; then
+            cat ${MODULES_FILE} | while read line; do test -n "${line}" && /sbin/modprobe ${line} &>/dev/null; done
         fi
 
         msg_done
diff --git a/board/common/overlay/etc/init.d/S03hostname b/board/common/overlay/etc/init.d/S03hostname
index 8b886e838d..a463779274 100755
--- a/board/common/overlay/etc/init.d/S03hostname
+++ b/board/common/overlay/etc/init.d/S03hostname
@@ -1,31 +1,26 @@
 #!/bin/bash
 
-sys_hostname_file="/etc/hostname"
-boot_hostname_file="/boot/hostname"
-hostname_file="/data/etc/hostname"
+SYS_HOSTNAME_FILE="/etc/hostname"
+BOOT_HOSTNAME_FILE="/boot/hostname"
+HOSTNAME_FILE="/data/etc/hostname"
 
-test -n "$os_version" || source /etc/init.d/base
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 case "$1" in
     start)
         msg_begin "Setting hostname"
 
-        if ! [[ -f $hostname_file ]]; then
-            if [[ -f $boot_hostname_file ]]; then
-                cp $boot_hostname_file $hostname_file
-            elif [[ -f $sys_hostname_file ]]; then
-                cp $sys_hostname_file $hostname_file
-            fi
-        fi
+        prepare_conf ${HOSTNAME_FILE} ${SYS_HOSTNAME_FILE} ${BOOT_HOSTNAME_FILE}
 
-        if [[ -f $hostname_file ]]; then
-            hostname=$(cat $hostname_file)
+        if [[ -f ${HOSTNAME_FILE} ]]; then
+            hostname=$(cat ${HOSTNAME_FILE})
         else
-            hostname="$os_prefix-$board_sn"
+            hostname="${OS_PREFIX}-${BOARD_SN}"
         fi
 
-        /bin/hostname $hostname
-        echo "127.0.0.1 localhost $hostname" > /etc/hosts
+        /bin/hostname ${hostname}
+        echo "127.0.0.1 localhost ${hostname}" > /etc/hosts
 
         msg_done
         ;;
diff --git a/board/common/overlay/etc/init.d/S04syslog b/board/common/overlay/etc/init.d/S04syslog
index b7a1eb3ac4..facaeedb98 100755
--- a/board/common/overlay/etc/init.d/S04syslog
+++ b/board/common/overlay/etc/init.d/S04syslog
@@ -1,16 +1,17 @@
 #!/bin/bash
 
-test -n "$os_version" || source /etc/init.d/base
+test -n "${OS_VERSION}" || source /etc/init.d/base
+
+DMESG_LOG="/var/log/dmesg.log"
 
-dmesg_log="/var/log/dmesg.log"
 
 case "$1" in
     start)
         msg_begin "Starting syslogd"
         syslogd
         test $? == 0 && msg_done || msg_fail
-        echo "---- booting $os_name $os_version ----" >> $dmesg_log
-        dmesg -T -w >> $dmesg_log &
+        echo "---- booting ${OS_NAME} ${OS_VERSION} ----" >> ${DMESG_LOG}
+        dmesg -T -w >> ${DMESG_LOG} &
         ;;
 
     stop)
diff --git a/board/common/overlay/etc/init.d/S12udev b/board/common/overlay/etc/init.d/S12udev
index ce1c2af7f8..3228aefc17 100755
--- a/board/common/overlay/etc/init.d/S12udev
+++ b/board/common/overlay/etc/init.d/S12udev
@@ -1,10 +1,13 @@
 #!/bin/bash
 
-test -f /etc/udev/udev.conf || exit 0
+CONF=/etc/udev/udev.conf
 
-test -n "$os_version" || source /etc/init.d/base
 
-source /etc/udev/udev.conf
+test -f ${CONF} || exit 0
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
+
+source ${CONF}
 
 start() {
     msg_begin "Starting eudev"
diff --git a/board/common/overlay/etc/init.d/S13watchdog b/board/common/overlay/etc/init.d/S13watchdog
index 2ef0f11278..331bdcfc66 100755
--- a/board/common/overlay/etc/init.d/S13watchdog
+++ b/board/common/overlay/etc/init.d/S13watchdog
@@ -2,7 +2,7 @@
 
 test -c /dev/watchdog || exit 0
 
-test -n "$os_version" || source /etc/init.d/base
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 case "$1" in
     start)
diff --git a/board/common/overlay/etc/init.d/S14postupgrade b/board/common/overlay/etc/init.d/S14postupgrade
index 65c0adf96b..248bb2c2ef 100755
--- a/board/common/overlay/etc/init.d/S14postupgrade
+++ b/board/common/overlay/etc/init.d/S14postupgrade
@@ -1,19 +1,18 @@
 #!/bin/bash
 
-test -n "$os_version" || source /etc/init.d/base
+SYS_VERSION_FILE="/etc/version"
+VERSION_FILE="/data/etc/version"
+POST_UPGRADE_DIR="/usr/share/post-upgrade"
 
-sys_version_file="/etc/version"
-version_file="/data/etc/version"
-post_upgrade_dir="/usr/share/post-upgrade"
-sys_os_conf="/etc/os.conf"
-os_conf="/data/etc/os.conf"
 
-hash=$(md5sum $version_file 2>/dev/null | cut -d ' ' -f 1)
-sys_hash=$(md5sum $sys_version_file 2>/dev/null | cut -d ' ' -f 1)
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
-test "$hash" == "$sys_hash" && exit 0
+hash=$(md5sum ${VERSION_FILE} 2>/dev/null | cut -d ' ' -f 1)
+sys_hash=$(md5sum ${SYS_VERSION_FILE} 2>/dev/null | cut -d ' ' -f 1)
 
-test -d $post_upgrade_dir || exit 0
+test "${hash}" == "${sys_hash}" && exit 0
+
+test -d ${POST_UPGRADE_DIR} || exit 0
 
 function version_gt() {
     if [[ "$1" != "$2" ]] && [[ $(echo -e "$2\n$1" | sort -t . | head -n 1) == "$2" ]]; then
@@ -24,28 +23,16 @@ function version_gt() {
 }
 
 function run_post_upgrade() {
-    version="$(source $version_file 2>/dev/null && echo $os_version)"
-    sys_version="$(source $sys_version_file 2>/dev/null && echo $os_version)"
+    version="$(source ${VERSION_FILE} 2>/dev/null && echo ${OS_VERSION})"
+    sys_version="$(source ${SYS_VERSION_FILE} 2>/dev/null && echo ${OS_VERSION})"
 
-    versions=$(ls -1 $post_upgrade_dir | cut -d '.' -f 1)
-    for v in $versions; do
-        if [[ -z "$version" ]] || version_gt $v $version; then
-            msg_begin "Post-upgrading to version $v"
-            out=$($post_upgrade_dir/$v.sh 2>&1)
+    versions=$(ls -1 ${POST_UPGRADE_DIR} | cut -d '.' -f 1)
+    for v in ${versions}; do
+        if [[ -z "${version}" ]] || version_gt ${v} ${version}; then
+            msg_begin "Post-upgrading to version ${v}"
+            out=$(${POST_UPGRADE_DIR}/${v}.sh 2>&1)
             test $? == 0 && msg_done || msg_fail
-            echo "$out" | logger -t post-upgrade
-        fi
-    done
-}
-
-function update_os_conf() {
-    source $sys_os_conf
-    sys_vars=$(cat $sys_os_conf | cut -d '=' -f 1)
-    for var in $sys_vars; do
-        if ! grep "$var=" $os_conf &>/dev/null; then
-            msg_begin "Adding $var to os.conf"
-            echo "$var=\"${!var}\"" >> $os_conf
-            msg_done
+            echo "${out}" | logger -t post-upgrade
         fi
     done
 }
@@ -53,8 +40,7 @@ function update_os_conf() {
 case "$1" in
     start)
         run_post_upgrade
-        cp $sys_version_file $version_file
-        update_os_conf
+        cp ${SYS_VERSION_FILE} ${VERSION_FILE}
         ;;
 
     stop)
diff --git a/board/common/overlay/etc/init.d/S30dbus b/board/common/overlay/etc/init.d/S30dbus
index 946aa5271d..5f9bc53f4e 100755
--- a/board/common/overlay/etc/init.d/S30dbus
+++ b/board/common/overlay/etc/init.d/S30dbus
@@ -1,15 +1,16 @@
 #!/bin/bash
 
-sys_btconf="/etc/bluetooth.conf"
-boot_btconf="/boot/bluetooth.conf"
-btconf="/data/etc/bluetooth.conf"
+SYS_BTCONF="/etc/bluetooth.conf"
+BOOT_BTCONF="/boot/bluetooth.conf"
+BTCONF="/data/etc/bluetooth.conf"
+
 
 # dbus is currently only used by bluez
-test -f $btconf || test -f $boot_btconf || test -f $sys_btconf || exit 0
+test -f ${BTCONF} || test -f ${BOOT_BTCONF} || test -f ${SYS_BTCONF} || exit 0
 
 test -x /usr/bin/dbus-daemon || exit 0
 
-test -n "$os_version" || source /etc/init.d/base
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 start() {
     mkdir -p /tmp/dbus
diff --git a/board/common/overlay/etc/init.d/S33hostapd b/board/common/overlay/etc/init.d/S33hostapd
index b8d6759589..d25ffae608 100755
--- a/board/common/overlay/etc/init.d/S33hostapd
+++ b/board/common/overlay/etc/init.d/S33hostapd
@@ -1,30 +1,25 @@
 #!/bin/bash
 
-sys_conf="/etc/hostapd.conf"
-boot_conf="/boot/hostapd.conf"
-conf="/data/etc/hostapd.conf"
+SYS_CONF="/etc/hostapd.conf"
+BOOT_CONF="/boot/hostapd.conf"
+CONF="/data/etc/hostapd.conf"
 
-log="/var/log/hostapd.log"
-prog="/usr/sbin/hostapd"
+LOG="/var/log/hostapd.log"
+PROG="/usr/sbin/hostapd"
 
-watch_conf="/data/etc/watch.conf"
+WATCH_CONF="/data/etc/watch.conf"
 
 link_watch=yes
 link_watch_timeout=20
 
-test -f $watch_conf && source $watch_conf
 
-if ! [[ -f $conf ]]; then
-    if [[ -f $boot_conf ]]; then
-        cp $boot_conf $conf
-    elif [[ -f $sys_conf ]]; then
-        cp $sys_conf $conf
-    fi
-fi
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
-test -f $conf || exit 0
+prepare_conf ${CONF} ${SYS_CONF} ${BOOT_CONF}
+test -f ${CONF} || exit 0
+
+test -f ${WATCH_CONF} && source ${WATCH_CONF}
 
-test -n "$os_version" || source /etc/init.d/base
 
 running() {
     killall -0 hostapd &> /dev/null
@@ -46,26 +41,26 @@ start() {
 
     # wait up to 5 seconds for interface
     count=0
-    while ! ifconfig $iface >/dev/null 2>&1; do
+    while ! ifconfig ${iface} >/dev/null 2>&1; do
         sleep 1
-        count=$(($count + 1))
-        if [[ $count -ge 5 ]]; then
+        count=$((${count} + 1))
+        if [[ ${count} -ge 5 ]]; then
             msg_fail "no device"
             return 1
         fi
     done
 
-    iface=$(cat $conf | grep interface | cut -d '=' -f 2)
-    module=$(basename $(readlink /sys/class/net/$iface/device/driver/module 2>/dev/null) 2>/dev/null)
+    iface=$(cat ${CONF} | grep interface | cut -d '=' -f 2)
+    module=$(basename $(readlink /sys/class/net/${iface}/device/driver/module 2>/dev/null) 2>/dev/null)
 
-    iwconfig $iface power off &> /dev/null
-    $prog $conf &> $log &
+    iwconfig ${iface} power off &> /dev/null
+    ${PROG} ${CONF} &> ${LOG} &
 
-    if [[ "$link_watch" == "yes" ]]; then
+    if [[ "${LINK_WATCH}" == "yes" ]]; then
         watch &
     fi
 
-    test -n "$module" && msg_done "done ($module)"|| msg_done
+    test -n "${module}" && msg_done "done (${module})"|| msg_done
 }
 
 stop() {
diff --git a/board/common/overlay/etc/init.d/S35wifi b/board/common/overlay/etc/init.d/S35wifi
index 60ec787932..93294aad89 100755
--- a/board/common/overlay/etc/init.d/S35wifi
+++ b/board/common/overlay/etc/init.d/S35wifi
@@ -1,56 +1,35 @@
 #!/bin/bash
 
-sys_conf="/etc/wpa_supplicant.conf"
-boot_conf="/boot/wpa_supplicant.conf"
-conf="/data/etc/wpa_supplicant.conf"
+SYS_CONF="/etc/wpa_supplicant.conf"
+BOOT_CONF="/boot/wpa_supplicant.conf"
+CONF="/data/etc/wpa_supplicant.conf"
 
-log="/var/log/wpa_supplicant.log"
-prog="/usr/sbin/wpa_supplicant"
-driver=nl80211,wext
+LOG="/var/log/wpa_supplicant.log"
+PROG="/usr/sbin/wpa_supplicant"
+DRIVER=nl80211,wext
 
-sys_watch_conf="/etc/watch.conf"
-boot_watch_conf="/boot/watch.conf"
-watch_conf="/data/etc/watch.conf"
+SYS_WATCH_CONF="/etc/watch.conf"
+BOOT_WATCH_CONF="/boot/watch.conf"
+WATCH_CONF="/data/etc/watch.conf"
 
-if ! [[ -f $watch_conf ]]; then
-    if [[ -f $boot_watch_conf ]]; then
-        cp $boot_watch_conf $watch_conf
-    elif [[ -f $sys_watch_conf ]]; then
-        cp $sys_watch_conf $watch_conf
-    fi
-fi
 
-source $watch_conf
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
-if [[ -f $boot_conf ]]; then
-    cp -f $boot_conf $conf
-    grep -E "/boot .*ro[\s,]" /proc/mounts
-    RO=$?
-    test $RO == 0 && mount -o remount,rw /boot
-    rm -f $boot_conf
-    test $RO == 0 && mount -o remount,ro /boot
-fi
+prepare_conf ${WATCH_CONF} ${SYS_WATCH_CONF} ${BOOT_WATCH_CONF}
+source ${WATCH_CONF}
 
-if ! [[ -f $conf ]]; then
-    if [[ -f $sys_conf ]]; then
-        cp $sys_conf $conf
-    fi
-fi
+prepare_conf ${CONF} ${SYS_CONF} ${BOOT_CONF}
+test -f ${CONF} || exit 0
 
-test -f $conf || exit 0
+ssid=$(cat ${CONF} | grep ssid | grep -v scan_ssid | cut -d '"' -f 2)
+test -n "${ssid}" || exit 0
 
-# we want only Unix newlines here
-sed -i 's/\r//g' $conf
 
-ssid=$(cat $conf | grep ssid | grep -v scan_ssid | cut -d '"' -f 2)
-test -n "$ssid" || exit 0
+test "${OS_NETWORKLESS}" == "true" && exit 0
 
-test -n "$os_version" || source /etc/init.d/base
-
-test "$os_networkless" == "true" && exit 0
 
 connected() {
-    ip link show dev $os_wlan 2>&1 | grep LOWER_UP &> /dev/null && return 0 || return 1
+    ip link show dev ${OS_WLAN} 2>&1 | grep LOWER_UP &> /dev/null && return 0 || return 1
 }
 
 watch() {
@@ -60,11 +39,11 @@ watch() {
         if connected; then
             count=0
         else
-            if [[ $count -lt $link_watch_timeout ]]; then
-                count=$(($count + 5))
+            if [[ ${count} -lt ${LINK_WATCH_TIMEOUT} ]]; then
+                count=$((${count} + 5))
                 logger -t wifi -s "disconnected"
             else
-                logger -t wifi -s "disconnected for $link_watch_timeout seconds, calling panic action"
+                logger -t wifi -s "disconnected for ${LINK_WATCH_TIMEOUT} seconds, calling panic action"
                 panic_action wifi
             fi
         fi
@@ -72,26 +51,26 @@ watch() {
 }
 
 start() {
-    test -n "$os_country" && iw reg set $os_country
+    test -n "${OS_COUNTRY}" && iw reg set ${OS_COUNTRY}
 
     msg_begin "Starting wpa_supplicant"
 
     # wait up to 5 seconds for interface
     count=0
-    while ! ifconfig $os_wlan >/dev/null 2>&1; do
+    while ! ifconfig ${OS_WLAN} >/dev/null 2>&1; do
         sleep 1
-        count=$(($count + 1))
-        if [[ $count -ge 5 ]]; then
+        count=$((${count} + 1))
+        if [[ ${count} -ge 5 ]]; then
             msg_fail "no device"
             return 1
         fi
     done
     
-    module=$(basename $(readlink /sys/class/net/$os_wlan/device/driver/module 2>/dev/null) 2>/dev/null)
+    module=$(basename $(readlink /sys/class/net/${OS_WLAN}/device/driver/module 2>/dev/null) 2>/dev/null)
 
-    iwconfig $os_wlan power off &> /dev/null
-    iw $os_wlan set power_save off &> /dev/null
-    $prog -i$os_wlan -c$conf -D$driver -B &> $log
+    iwconfig ${OS_WLAN} power off &> /dev/null
+    iw ${OS_WLAN} set power_save off &> /dev/null
+    ${PROG} -i${OS_WLAN} -c${CONF} -D${DRIVER} -B &> ${LOG}
     count=0
     while true; do
         sleep 1
@@ -100,19 +79,19 @@ start() {
             break
         fi
 
-        if [[ $count -gt $link_watch_timeout ]] || ! pidof wpa_supplicant > /dev/null; then
-            test -n "$module" && msg_fail "failed ($module)"|| msg_fail
+        if [[ ${count} -gt ${LINK_WATCH_TIMEOUT} ]] || ! pidof wpa_supplicant > /dev/null; then
+            test -n "${module}" && msg_fail "failed (${module})"|| msg_fail
             return 1
         fi
 
-        count=$(($count + 1))
+        count=$((${count} + 1))
     done
 
-    if [[ "$link_watch" == "true" ]]; then
+    if [[ "${LINK_WATCH}" == "true" ]]; then
         watch &
     fi
 
-    test -n "$module" && msg_done "done ($module)"|| msg_done
+    test -n "${module}" && msg_done "done (${module})"|| msg_done
 }
 
 stop() {
diff --git a/board/common/overlay/etc/init.d/S36ppp b/board/common/overlay/etc/init.d/S36ppp
index c67f7253e6..14dbe7cd6c 100755
--- a/board/common/overlay/etc/init.d/S36ppp
+++ b/board/common/overlay/etc/init.d/S36ppp
@@ -1,33 +1,29 @@
 #!/bin/bash
 
-sys_conf="/etc/ppp/default"
-boot_conf="/boot/ppp"
-conf="/data/etc/ppp"
+SYS_CONF="/etc/ppp/default"
+BOOT_CONF="/boot/ppp"
+CONF="/data/etc/ppp"
 
-prog="/usr/sbin/pppd"
-provider="mobile"
+PROG="/usr/sbin/pppd"
+PROVIDER="mobile"
 
-watch_conf="/data/etc/watch.conf"
+WATCH_CONF="/data/etc/watch.conf"
 
-source $watch_conf
 
-if ! [[ -d $conf ]]; then
-    if [[ -d $boot_conf ]]; then
-        cp -r $boot_conf $conf
-    elif [[ -d $sys_conf ]]; then
-        cp -r $sys_conf $conf
-    fi
-fi
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
-test -e $conf/modem || exit 0
-test -e $conf/apn || exit 0
+prepare_conf ${CONF} ${SYS_CONF} ${BOOT_CONF}
 
-test -n "$os_version" || source /etc/init.d/base
+test -e ${CONF}/modem || exit 0
+test -e ${CONF}/apn || exit 0
+
+source ${WATCH_CONF}
+
+test "${OS_NETWORKLESS}" == "true" && exit 0
 
-test "$os_networkless" == "true" && exit 0
 
 connected() {
-    ifconfig | grep $os_ppp &>/dev/null && return 0 || return 1
+    ifconfig | grep ${OS_PPP} &>/dev/null && return 0 || return 1
 }
 
 watch() {
@@ -37,11 +33,11 @@ watch() {
         if connected; then
             count=0
         else
-            if [[ $count -lt $link_watch_timeout ]]; then
-                count=$(($count + 5))
+            if [[ ${count} -lt ${LINK_WATCH_TIMEOUT} ]]; then
+                count=$((${count} + 5))
                 logger -t ppp -s "disconnected"
             else
-                logger -t ppp -s "disconnected for $link_watch_timeout seconds, calling panic action"
+                logger -t ppp -s "disconnected for ${LINK_WATCH_TIMEOUT} seconds, calling panic action"
                 panic_action ppp
             fi
         fi
@@ -55,35 +51,35 @@ udev_trigger_add() {
 }
 
 start() {
-    test -e $conf/auth || touch $conf/auth
-    test -e $conf/extra || touch $conf/extra
-    test -e $conf/pin || touch $conf/pin
+    test -e ${CONF}/auth || touch ${CONF}/auth
+    test -e ${CONF}/extra || touch ${CONF}/extra
+    test -e ${CONF}/pin || touch ${CONF}/pin
     mknod /dev/ppp c 108 0 &>/dev/null
 
     msg_begin "Starting pppd"
 
     # wait for modem
-    modem=$(head -n 1 $conf/modem)
-    if ! [[ -e /dev/$modem ]]; then
+    modem=$(head -n 1 ${CONF}/modem)
+    if ! [[ -e /dev/${modem} ]]; then
         udev_trigger_add 4 &
     fi
 
     count=0
     while true; do
-        if [[ -e /dev/$modem ]] || [[ $count -gt $link_watch_timeout ]]; then
+        if [[ -e /dev/${modem} ]] || [[ ${count} -gt ${LINK_WATCH_TIMEOUT} ]]; then
             break
         fi
 
-        count=$(($count + 1))
+        count=$((${count} + 1))
         sleep 1
     done
 
-    if ! [[ -e /dev/$modem ]]; then
-        msg_fail "modem /dev/$modem not present"
+    if ! [[ -e /dev/${modem} ]]; then
+        msg_fail "modem /dev/${modem} not present"
         return
     fi
 
-    $prog call $provider
+    ${PROG} call ${PROVIDER}
     count=0
     while true; do
         sleep 1
@@ -92,15 +88,15 @@ start() {
             break
         fi
 
-        if [[ $count -gt $link_watch_timeout ]] || ! pidof pppd > /dev/null; then
+        if [[ ${count} -gt ${LINK_WATCH_TIMEOUT} ]] || ! pidof pppd > /dev/null; then
             msg_fail
             return
         fi
 
-        count=$(($count + 1))
+        count=$((${count} + 1))
     done
 
-    if [[ "$link_watch" == "true" ]]; then
+    if [[ "${LINK_WATCH}" == "true" ]]; then
         watch &
     fi
 
diff --git a/board/common/overlay/etc/init.d/S37bluetooth b/board/common/overlay/etc/init.d/S37bluetooth
index 76e570ab00..8d2fde898d 100755
--- a/board/common/overlay/etc/init.d/S37bluetooth
+++ b/board/common/overlay/etc/init.d/S37bluetooth
@@ -1,18 +1,14 @@
 #!/bin/bash
 
-sys_conf="/etc/bluetooth.conf"
-boot_conf="/boot/bluetooth.conf"
-conf="/data/etc/bluetooth.conf"
+SYS_CONF="/etc/bluetooth.conf"
+BOOT_CONF="/boot/bluetooth.conf"
+CONF="/data/etc/bluetooth.conf"
 
-if ! [[ -f $conf ]]; then
-    if [[ -f $boot_conf ]]; then
-        cp $boot_conf $conf
-    elif [[ -f $sys_conf ]]; then
-        cp $sys_conf $conf
-    fi
-fi
 
-test -f $conf || exit 0
+test -n "${OS_VERSION}" || source /etc/init.d/base
+
+prepare_conf ${CONF} ${SYS_CONF} ${BOOT_CONF}
+test -f ${CONF} || exit 0
 
 hci=hci0
 bluetoothd=/usr/libexec/bluetooth/bluetoothd
@@ -20,22 +16,21 @@ data_dir=/var/lib/bluetooth
 run_data_dir=/data/bluetooth
 run_conf=/var/lib/bluetooth.conf
 
-test -x $bluetoothd || exit 0
+test -x ${bluetoothd} || exit 0
 
-test -n "$os_version" || source /etc/init.d/base
 
 configure() {
-    mkdir -p $run_data_dir
-    ln -sf $run_data_dir $data_dir
-    cp $conf $run_conf
+    mkdir -p ${run_data_dir}
+    ln -sf ${run_data_dir} ${data_dir}
+    cp ${CONF} ${run_conf}
 
     # if no specific name configured, use hostname
-    if ! grep -E 'Name\s*=' $run_conf &>/dev/null; then
-        sed -ri "s/(\[General\])/\1\nName = $(hostname)/" $run_conf
+    if ! grep -E 'Name\s*=' ${run_conf} &>/dev/null; then
+        sed -ri "s/(\[General\])/\1\nName = $(hostname)/" ${run_conf}
     fi
     
     # bring adapter up
-    hciconfig $hci up
+    hciconfig ${hci} up
 }
 
 start() {
@@ -43,10 +38,10 @@ start() {
 
     # wait up to 10 seconds for device
     count=0
-    while ! hciconfig $hci &>/dev/null; do
+    while ! hciconfig ${hci} &>/dev/null; do
         sleep 1
-        count=$(($count + 1))
-        if [[ $count -ge 10 ]]; then
+        count=$((${count} + 1))
+        if [[ ${count} -ge 10 ]]; then
             msg_fail "no device"
             logger -t bluetooth -s "bluetooth device not available, calling panic action"
             panic_action bluetooth
@@ -62,13 +57,13 @@ start() {
     fi
 
     msg_begin "Starting bluetoothd"
-    $bluetoothd &>/dev/null &
+    ${bluetoothd} &>/dev/null &
     msg_done
 
     # if DiscoverableTimeout is set to 0, make adapter discoverable from boot time
-    if grep -E '^DiscoverableTimeout\s*=\s*0$' $run_conf &>/dev/null; then
+    if grep -E '^DiscoverableTimeout\s*=\s*0$' ${run_conf} &>/dev/null; then
         sleep 1
-        hciconfig $hci piscan
+        hciconfig ${hci} piscan
     fi
 }
 
diff --git a/board/common/overlay/etc/init.d/S40network b/board/common/overlay/etc/init.d/S40network
index 93b03c81af..c4ea325b29 100755
--- a/board/common/overlay/etc/init.d/S40network
+++ b/board/common/overlay/etc/init.d/S40network
@@ -1,40 +1,36 @@
 #!/bin/bash
 
+DH_CONF="/var/cache/dhclient.conf"
+SYS_STATIC_CONF="/etc/static_ip.conf"
+BOOT_STATIC_CONF="/boot/static_ip.conf"
+STATIC_CONF="/data/etc/static_ip.conf"
+WATCH_CONF="/data/etc/watch.conf"
+
+LINK_NEGO_TIMEOUT=10
+
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
+
+source ${WATCH_CONF}
+
+prepare_conf ${STATIC_CONF} ${SYS_STATIC_CONF} ${BOOT_STATIC_CONF}
+test -r ${STATIC_CONF} && source ${STATIC_CONF}
+
 mkdir -p /var/lib/dhcp
-dh_conf="/var/cache/dhclient.conf"
-sys_static_conf="/etc/static_ip.conf"
-boot_static_conf="/boot/static_ip.conf"
-static_conf="/data/etc/static_ip.conf"
-watch_conf="/data/etc/watch.conf"
 
-link_nego_timeout=10
-
-source $watch_conf
-
-if ! [[ -f $static_conf ]]; then
-    if [[ -f $boot_static_conf ]]; then
-        cp $boot_static_conf $static_conf
-    elif [[ -f $sys_static_conf ]]; then
-        cp $sys_static_conf $static_conf
-    fi
-fi
-
-test -r $static_conf && source $static_conf
-
-test -n "$os_version" || source /etc/init.d/base
 
 watch_eth() {
     count=0
     while true; do
         sleep 5
-        if [[ "$(cat /sys/class/net/$os_eth/operstate 2>/dev/null)" == "up" ]]; then
+        if [[ "$(cat /sys/class/net/${OS_ETH}/operstate 2>/dev/null)" == "up" ]]; then
             count=0
         else
-            if [[ $count -lt $link_watch_timeout ]]; then
-                count=$(($count + 5))
+            if [[ ${count} -lt ${LINK_WATCH_TIMEOUT} ]]; then
+                count=$((${count} + 5))
                 logger -t ethernet -s "disconnected"
             else
-                logger -t ethernet -s "disconnected for $link_watch_timeout seconds, calling panic action"
+                logger -t ethernet -s "disconnected for ${LINK_WATCH_TIMEOUT} seconds, calling panic action"
                 panic_action network
             fi
         fi
@@ -46,14 +42,14 @@ watch_ip() {
     count=0
     while true; do
         sleep 5
-        if ip addr show dev $iface | grep inet &>/dev/null; then
+        if ip addr show dev ${iface} | grep inet &>/dev/null; then
             count=0
         else
-            if [[ $count -lt $ip_watch_timeout ]]; then
-                count=$(($count + 5))
-                logger -t network -s "$iface has no IP address"
+            if [[ ${count} -lt ${IP_WATCH_TIMEOUT} ]]; then
+                count=$((${count} + 5))
+                logger -t network -s "${iface} has no IP address"
             else
-                logger -t network -s "$iface had no IP address for $ip_watch_timeout seconds, calling panic action"
+                logger -t network -s "${iface} had no IP address for ${IP_WATCH_TIMEOUT} seconds, calling panic action"
                 panic_action network
             fi
         fi
@@ -66,31 +62,31 @@ start_lo() {
 
 start_wlan() {
     msg_begin "Configuring wireless network"
-    if ! ifconfig $os_wlan &>/dev/null; then
+    if ! ifconfig ${OS_WLAN} &>/dev/null; then
         msg_fail "no device"
         return 1
     fi
 
-    if [[ "$(cat /sys/class/net/$os_wlan/carrier 2>/dev/null)" != "1" ]]; then
+    if [[ "$(cat /sys/class/net/${OS_WLAN}/carrier 2>/dev/null)" != "1" ]]; then
         msg_fail "no link"
         return 1
     fi
 
-    if [[ -n "$mtu" ]]; then
-        ip link set mtu $mtu dev $os_wlan
+    if [[ -n "${mtu}" ]]; then
+        ip link set mtu ${mtu} dev ${OS_WLAN}
     fi
 
-    if [[ -n "$static_ip" ]]; then
-        msg_done $static_ip
-        ifconfig $os_wlan $static_ip up
-        static_ip="" # won't be used again
+    if [[ -n "${STATIC_IP}" ]]; then
+        msg_done ${STATIC_IP}
+        ifconfig ${OS_WLAN} ${STATIC_IP} up
+        STATIC_IP="" # won't be used again
     else
         msg_done dhcp
-        dhclient -cf "$dh_conf" $os_wlan
+        dhclient -cf "${DH_CONF}" ${OS_WLAN}
     fi
 
-    if [[ "$ip_watch" == "true" ]] && ip addr show dev $os_wlan | grep inet &>/dev/null; then
-        watch_ip $os_wlan &
+    if [[ "${IP_WATCH}" == "true" ]] && ip addr show dev ${OS_WLAN} | grep inet &>/dev/null; then
+        watch_ip ${OS_WLAN} &
     fi
 }
 
@@ -100,86 +96,86 @@ start_eth() {
     # wait for driver
     w=3
     count=0
-    while ! ifconfig $os_eth >/dev/null 2>&1; do
+    while ! ifconfig ${OS_ETH} >/dev/null 2>&1; do
         sleep 1
-        count=$(($count + 1))
-        if [[ $count -ge $w ]]; then
+        count=$((${count} + 1))
+        if [[ ${count} -ge ${w} ]]; then
             msg_done "no device"
             return 1
         fi
     done
 
     # bring it up
-    ifconfig $os_eth up
+    ifconfig ${OS_ETH} up
 
     # wait for operstate
     w=3
     count=0
-    while [[ "$(cat /sys/class/net/$os_eth/operstate 2>&1)" == "unknown" ]]; do
+    while [[ "$(cat /sys/class/net/${OS_ETH}/operstate 2>&1)" == "unknown" ]]; do
         sleep 1
-        count=$(($count + 1))
-        if [[ $count -ge $w ]]; then
+        count=$((${count} + 1))
+        if [[ ${count} -ge ${w} ]]; then
             msg_done "no link"
             return 1
         fi
     done
 
     # wait for link
-    test "$link_watch" == "true" || link_nego_timeout=5
+    test "${LINK_WATCH}" == "true" || LINK_NEGO_TIMEOUT=5
     count=0
-    while [[ "$(cat /sys/class/net/$os_eth/carrier 2>&1)" != "1" ]]; do
+    while [[ "$(cat /sys/class/net/${OS_ETH}/carrier 2>&1)" != "1" ]]; do
         sleep 1
-        count=$(($count + 1))
-        if [[ $count -ge $link_nego_timeout ]]; then
+        count=$((${count} + 1))
+        if [[ ${count} -ge ${LINK_NEGO_TIMEOUT} ]]; then
             msg_done "no link"
             return 1
         fi
     done
     
-    if [[ -n "$mtu" ]]; then
-        ip link set mtu $mtu dev $os_eth
+    if [[ -n "${mtu}" ]]; then
+        ip link set mtu ${mtu} dev ${OS_ETH}
     fi
 
-    if [[ -n "$static_ip" ]]; then
-        msg_done $static_ip
-        ifconfig $os_eth $static_ip up
-        static_ip="" # won't be used again
+    if [[ -n "${STATIC_IP}" ]]; then
+        msg_done ${STATIC_IP}
+        ifconfig ${OS_ETH} ${STATIC_IP} up
+        STATIC_IP="" # won't be used again
     else
         msg_done dhcp
-        dhclient -cf "$dh_conf" $os_eth
+        dhclient -cf "${DH_CONF}" ${OS_ETH}
     fi
 
-    if [[ "$link_watch" == "true" ]]; then
+    if [[ "${LINK_WATCH}" == "true" ]]; then
         watch_eth &
     fi
 
-    if [[ "$ip_watch" == "true" ]] && ip addr show dev $os_eth | grep inet &>/dev/null; then
-        watch_ip $os_eth &
+    if [[ "${IP_WATCH}" == "true" ]] && ip addr show dev ${OS_ETH} | grep inet &>/dev/null; then
+        watch_ip ${OS_ETH} &
     fi
 }
 
 start() {
     hostname=$(hostname)
-    echo "send host-name = \"$hostname\";" > /var/cache/dhclient.conf
+    echo "send host-name = \"${hostname}\";" > /var/cache/dhclient.conf
 
     start_lo
 
-    test "$os_networkless" == "true" && return 0
+    test "${OS_NETWORKLESS}" == "true" && return 0
 
     ssid=$(cat /data/etc/wpa_supplicant.conf 2>&1 | grep ssid | grep -v scan_ssid | cut -d '"' -f 2)
-    test -n "$ssid" && start_wlan && wlan_ok="ok"
+    test -n "${ssid}" && start_wlan && wlan_ok="ok"
     
-    test -r /data/etc/ppp/modem && ifconfig | grep $os_ppp &>/dev/null && ppp_ok="ok"
+    test -r /data/etc/ppp/modem && ifconfig | grep ${OS_PPP} &>/dev/null && ppp_ok="ok"
     
     # if wifi or ppp link ok, start eth in background
-    if [[ "$wlan_ok" == "ok" ]] || [[ "$ppp_ok" == "ok" ]]; then
+    if [[ "${wlan_ok}" == "ok" ]] || [[ "${ppp_ok}" == "ok" ]]; then
         start_eth &>/dev/null &
     else
         start_eth && eth_ok="ok"
     fi
     
-    if [[ "$eth_ok" != "ok" ]] && [[ "$wlan_ok" != "ok" ]] && [[ "$ppp_ok" != "ok" ]]; then
-        if [[ "$link_watch" == "true" ]]; then
+    if [[ "${eth_ok}" != "ok" ]] && [[ "${wlan_ok}" != "ok" ]] && [[ "${ppp_ok}" != "ok" ]]; then
+        if [[ "${LINK_WATCH}" == "true" ]]; then
             logger -t network -s "no network connection available, calling panic action"
             panic_action network
             return 1
@@ -189,15 +185,15 @@ start() {
         fi
     fi
 
-    if [[ -n "$static_gw" ]]; then
-        msg_begin "Setting static gateway to $static_gw"
-        ip route add default via $static_gw
+    if [[ -n "${STATIC_GW}" ]]; then
+        msg_begin "Setting static gateway to ${STATIC_GW}"
+        ip route add default via ${STATIC_GW}
         test $? == 0 && msg_done || msg_fail
     fi
 
-    if [[ -n "$static_dns" ]]; then
-        msg_begin "Setting static DNS server to $static_dns"
-        echo "nameserver $static_dns" > /etc/resolv.conf
+    if [[ -n "${STATIC_DNS}" ]]; then
+        msg_begin "Setting static DNS server to ${STATIC_DNS}"
+        echo "nameserver ${STATIC_DNS}" > /etc/resolv.conf
         test $? == 0 && msg_done || msg_fail
     fi
 }
diff --git a/board/common/overlay/etc/init.d/S41netwatch b/board/common/overlay/etc/init.d/S41netwatch
index a7bd496f32..cfab7e3c91 100755
--- a/board/common/overlay/etc/init.d/S41netwatch
+++ b/board/common/overlay/etc/init.d/S41netwatch
@@ -1,34 +1,36 @@
 #!/bin/bash
 
-watch_conf="/data/etc/watch.conf"
-netwatch_retries=3
-netwatch_timeout=5
-netwatch_interval=20
+WATCH_CONF="/data/etc/watch.conf"
+NETWATCH_RETRIES=3
+NETWATCH_TIMEOUT=5
+NETWATCH_INTERVAL=20
 
-test -f $watch_conf && source $watch_conf || exit 0
 
-if [[ -z "$netwatch_host" ]] || [[ -z "$netwatch_port" ]]; then
+test -f ${WATCH_CONF} && source ${WATCH_CONF} || exit 0
+
+if [[ -z "${NETWATCH_HOST}" || -z "${NETWATCH_PORT}" ]]; then
     exit 0
 fi
 
-test -n "$os_version" || source /etc/init.d/base
+test -n "${OS_VERSION}" || source /etc/init.d/base
+
+test "${OS_NETWORKLESS}" == "true" && exit 0
 
-test "$os_networkless" == "true" && exit 0
 
 watch() {
     count=0
-    netwatch_retries=$(($netwatch_retries - 1))
+    NETWATCH_RETRIES=$((${NETWATCH_RETRIES} - 1))
     while true; do
-        sleep $netwatch_interval
-        if nc -z -w $netwatch_timeout $netwatch_host $netwatch_port </dev/null >/dev/null 2>&1; then
+        sleep ${NETWATCH_INTERVAL}
+        if nc -z -w ${NETWATCH_TIMEOUT} ${NETWATCH_HOST} ${NETWATCH_PORT} </dev/null >/dev/null 2>&1; then
             count=0
         else
-            if [[ $count -lt $netwatch_retries ]]; then
-                logger -t netwatch -s "cannot connect to $netwatch_host:$netwatch_port"
-                count=$(($count + 1))
+            if [[ ${count} -lt ${NETWATCH_RETRIES} ]]; then
+                logger -t netwatch -s "cannot connect to ${NETWATCH_HOST}:${NETWATCH_PORT}"
+                count=$((${count} + 1))
                 continue
             else
-                logger -t netwatch -s "cannot connect to $netwatch_host:$netwatch_port, calling panic action"
+                logger -t netwatch -s "cannot connect to ${NETWATCH_HOST}:${NETWATCH_PORT}, calling panic action"
                 panic_action netwatch
             fi
         fi
diff --git a/board/common/overlay/etc/init.d/S43firewall b/board/common/overlay/etc/init.d/S43firewall
index 3e049c18d8..c588fd0d6d 100755
--- a/board/common/overlay/etc/init.d/S43firewall
+++ b/board/common/overlay/etc/init.d/S43firewall
@@ -1,25 +1,19 @@
 #!/bin/bash
 
-sys_conf="/etc/firewall.sh"
-boot_conf="/boot/firewall.sh"
-conf="/data/etc/firewall.sh"
+SYS_CONF="/etc/firewall.sh"
+BOOT_CONF="/boot/firewall.sh"
+CONF="/data/etc/firewall.sh"
 
-if ! [[ -f $conf ]]; then
-    if [[ -f $boot_conf ]]; then
-        cp $boot_conf $conf
-    elif [[ -f $sys_conf ]]; then
-        cp $sys_conf $conf
-    fi
-fi
 
-test -f $conf || exit 0
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
-test -n "$os_version" || source /etc/init.d/base
+prepare_conf ${CONF} ${SYS_CONF} ${BOOT_CONF}
+test -f ${CONF} || exit 0
 
 start() {
     msg_begin "Starting firewall"
 
-    bash $conf  
+    bash ${CONF}  
 
     test $? == 0 && msg_done || msg_fail
 }
diff --git a/board/common/overlay/etc/init.d/S45dnsmasq b/board/common/overlay/etc/init.d/S45dnsmasq
index e6c7c3ffed..df0d849cbe 100755
--- a/board/common/overlay/etc/init.d/S45dnsmasq
+++ b/board/common/overlay/etc/init.d/S45dnsmasq
@@ -1,33 +1,28 @@
 #!/bin/bash
 
-sys_conf="/etc/dnsmasq.conf"
-boot_conf="/boot/dnsmasq.conf"
-conf="/data/etc/dnsmasq.conf"
+SYS_CONF="/etc/dnsmasq.conf"
+BOOT_CONF="/boot/dnsmasq.conf"
+CONF="/data/etc/dnsmasq.conf"
 
-log="/var/log/dnsmasq.log"
-prog="/usr/sbin/dnsmasq"
+LOG="/var/log/dnsmasq.log"
+PROG="/usr/sbin/dnsmasq"
 
-if ! [[ -f $conf ]]; then
-    if [[ -f $boot_conf ]]; then
-        cp $boot_conf $conf
-    elif [[ -f $sys_conf ]]; then
-        cp $sys_conf $conf
-    fi
-fi
 
-test -f $conf || exit 0
+test -n "${OS_VERSION}" || source /etc/init.d/base
+
+prepare_conf ${CONF} ${SYS_CONF} ${BOOT_CONF}
+test -f ${CONF} || exit 0
 
-test -n "$os_version" || source /etc/init.d/base
 
 start() {
     msg_begin "Starting dnsmasq"
     
-    iface=$(cat $conf | grep interface | cut -d '=' -f 2)
-    ip=$(cat $conf | grep range | cut -d '=' -f 2 | cut -d '.' -f 1,2,3).1
+    iface=$(cat ${CONF} | grep interface | cut -d '=' -f 2)
+    ip=$(cat ${CONF} | grep range | cut -d '=' -f 2 | cut -d '.' -f 1,2,3).1
     
-    ifconfig $iface $ip
+    ifconfig ${iface} ${ip}
 
-    $prog -C $conf --log-facility=$log
+    ${PROG} -C ${CONF} --log-facility=${LOG}
 
     test $? == 0 && msg_done || msg_fail
 }
diff --git a/board/common/overlay/etc/init.d/S50date b/board/common/overlay/etc/init.d/S50date
index 0390037222..c449f275e3 100755
--- a/board/common/overlay/etc/init.d/S50date
+++ b/board/common/overlay/etc/init.d/S50date
@@ -1,64 +1,53 @@
 #!/bin/bash
 
 # Date executable points to /bin/busybox\ date explicitly in the cases that date binary gets overwritten
-date_exec=/bin/busybox\ date
+DATE_PROG=/bin/busybox\ date
 
-sys_conf="/etc/date.conf"
-boot_conf="/boot/date.conf"
-conf="/data/etc/date.conf"
+SYS_CONF="/etc/date.conf"
+BOOT_CONF="/boot/date.conf"
+CONF="/data/etc/date.conf"
 
-sys_ntp_conf="/etc/ntp.conf"
-boot_ntp_conf="/boot/ntp.conf"
-ntp_conf="/data/etc/ntp.conf"
+SYS_NTP_CONF="/etc/ntp.conf"
+BOOT_NTP_CONF="/boot/ntp.conf"
+NTP_CONF="/data/etc/ntp.conf"
 
-if ! [[ -f $conf ]]; then
-    if [[ -f $boot_conf ]]; then
-        cp $boot_conf $conf
-    elif [[ -f $sys_conf ]]; then
-        cp $sys_conf $conf
-    fi
-fi
 
-if ! [[ -f $ntp_conf ]]; then
-    if [[ -f $boot_ntp_conf ]]; then
-        cp $boot_ntp_conf $ntp_conf
-    elif [[ -f $sys_ntp_conf ]]; then
-        cp $sys_ntp_conf $ntp_conf
-    fi
-fi
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
-test -f $conf || exit 0
+prepare_conf ${CONF} ${SYS_CONF} ${BOOT_CONF}
+prepare_conf ${NTP_CONF} ${SYS_NTP_CONF} ${BOOT_NTP_CONF}
 
-test -n "$os_version" || source /etc/init.d/base
+test -f ${CONF} || exit 0
 
-test "$os_networkless" == "true" && exit 0
+test "${OS_NETWORKLESS}" == "true" && exit 0
 
 date_timeout=10
 date_method=http
 date_host="google.com"
 date_interval="900"
 
-source $conf
+source ${CONF}
+
 
 set_current_date_http() {
-    date_str=$(curl -v -s -m $date_timeout -X GET http://$date_host 2>&1 | grep Date | sed -e 's/< Date: //')
-    test -z "$date_str" && return 1
-    $date_exec -u -D "%a, %d %b %Y %H:%M:%S" -s "$date_str" > /dev/null
+    date_str=$(curl -v -s -m ${date_timeout} -X GET http://${date_host} 2>&1 | grep Date | sed -e 's/< Date: //')
+    test -z "${date_str}" && return 1
+    ${DATE_PROG} -u -D "%a, %d %b %Y %H:%M:%S" -s "${date_str}" > /dev/null
     return $?
 }
 
 set_current_date_ntp() {
-    cat $ntp_conf | grep server | head -n 1 | cut -d ' ' -f 2 | xargs ntpdate -t $date_timeout -s
+    cat ${NTP_CONF} | grep server | head -n 1 | cut -d ' ' -f 2 | xargs ntpdate -t ${date_timeout} -s
 }
 
 start_http() {
     msg_begin "Setting current date using http"
     set_current_date_http || set_current_date_http
-    test $? == 0 && msg_done "$($date_exec)" || msg_fail
+    test $? == 0 && msg_done "$(${DATE_PROG})" || msg_fail
     
     msg_begin "Starting http date updater"
     while true; do
-        sleep $date_interval
+        sleep ${date_interval}
         set_current_date_http
     done &
     msg_done
@@ -67,23 +56,23 @@ start_http() {
 start_ntp() {
     mkdir -p /var/lib/ntp
 
-    cat $ntp_conf | grep -v iburst > ${ntp_conf}.tmp
+    cat ${NTP_CONF} | grep -v iburst > ${NTP_CONF}.tmp
 
-    if [[ -n "$date_ntp_server" ]]; then
-        echo "server $date_ntp_server iburst" > $ntp_conf
+    if [[ -n "${date_ntp_server}" ]]; then
+        echo "server ${date_ntp_server} iburst" > ${NTP_CONF}
     else
-        cat $sys_ntp_conf | grep iburst > $ntp_conf
+        cat ${SYS_NTP_CONF} | grep iburst > ${NTP_CONF}
     fi
 
-    cat ${ntp_conf}.tmp >> $ntp_conf
-    rm ${ntp_conf}.tmp
+    cat ${NTP_CONF}.tmp >> ${NTP_CONF}
+    rm ${NTP_CONF}.tmp
 
     msg_begin "Setting current date using ntp"
     set_current_date_ntp || set_current_date_ntp
-    test $? == 0 && msg_done "$($date_exec)" || msg_fail
+    test $? == 0 && msg_done "$(${DATE_PROG})" || msg_fail
 
     msg_begin "Starting ntpd"
-    ntpd -g -c $ntp_conf
+    ntpd -g -c ${NTP_CONF}
     test $? == 0 && msg_done || msg_fail
 }
 
@@ -100,17 +89,17 @@ stop_ntp() {
 }
 
 start() {
-    if [[ "$date_method" == "http" ]]; then
+    if [[ "${date_method}" == "http" ]]; then
         start_http
     else
         start_ntp
     fi
 
-    echo "system date is $($date_exec '+%Y-%m-%d %H:%M:%S')" > /dev/kmsg
+    echo "system date is $(${DATE_PROG} '+%Y-%m-%d %H:%M:%S')" > /dev/kmsg
 }
 
 stop() {
-    if [[ "$date_method" == "http" ]]; then
+    if [[ "${date_method}" == "http" ]]; then
         stop_http
     else
         stop_ntp
diff --git a/board/common/overlay/etc/init.d/S51crond b/board/common/overlay/etc/init.d/S51crond
index 618b482e12..7485031ef7 100755
--- a/board/common/overlay/etc/init.d/S51crond
+++ b/board/common/overlay/etc/init.d/S51crond
@@ -1,19 +1,19 @@
 #!/bin/bash
 
-sys_conf="/etc/crontabs"
-conf="/data/etc/crontabs"
+SYS_CONF="/etc/crontabs"
+CONF="/data/etc/crontabs"
 
-test -n "$os_version" || source /etc/init.d/base
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 start() {
     msg_begin "Starting crond"
     
-    if [[ -d $sys_conf ]];  then
-        /usr/sbin/crond -c $sys_conf
+    if [[ -d ${SYS_CONF} ]];  then
+        /usr/sbin/crond -c ${SYS_CONF}
     fi
 
-    mkdir -p $conf
-    /usr/sbin/crond -c $conf
+    mkdir -p ${CONF}
+    /usr/sbin/crond -c ${CONF}
 
     test $? == 0 && msg_done || msg_fail
 }
diff --git a/board/common/overlay/etc/init.d/S60sshd b/board/common/overlay/etc/init.d/S60sshd
index 2dcd04ac7b..3d7f7620c2 100755
--- a/board/common/overlay/etc/init.d/S60sshd
+++ b/board/common/overlay/etc/init.d/S60sshd
@@ -1,12 +1,12 @@
 #!/bin/bash
 
-conf="/etc/sshd_config"
+CONF="/etc/sshd_config"
 
-test -f $conf || exit 0
+test -f ${CONF} || exit 0
 
-test -n "$os_version" || source /etc/init.d/base
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
-test "$os_networkless" == "true" && exit 0
+test "${OS_NETWORKLESS}" == "true" && exit 0
 
 start() {
     msg_begin "Starting sshd"
@@ -19,10 +19,10 @@ start() {
 
     umask 077
     hostname=$(hostname)
-    echo "Welcome to $hostname!" > /var/cache/sshd_banner
+    echo "Welcome to ${hostname}!" > /var/cache/sshd_banner
     sync
 
-    /usr/sbin/sshd -f $conf
+    /usr/sbin/sshd -f ${CONF}
     test $? == 0 && msg_done || msg_fail
 }
 
diff --git a/board/common/overlay/etc/init.d/S98userinit b/board/common/overlay/etc/init.d/S98userinit
index ffaf1dfb10..835229e78e 100755
--- a/board/common/overlay/etc/init.d/S98userinit
+++ b/board/common/overlay/etc/init.d/S98userinit
@@ -1,15 +1,16 @@
 #!/bin/bash
 
-userinit_sh="/data/etc/userinit.sh"
+USERINIT="/data/etc/userinit.sh"
 
-test -f $userinit_sh || exit 0
 
-test -n "$os_version" || source /etc/init.d/base
+test -f ${USERINIT} || exit 0
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 case "$1" in
     start)
         msg_begin "Executing user init script"
-        /bin/bash $userinit_sh
+        /bin/bash ${USERINIT}
         test $? == 0 && msg_done || msg_fail
         ;;
 
diff --git a/board/common/overlay/etc/init.d/S99showinfo b/board/common/overlay/etc/init.d/S99showinfo
index fac00a387d..8758c62c31 100755
--- a/board/common/overlay/etc/init.d/S99showinfo
+++ b/board/common/overlay/etc/init.d/S99showinfo
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-test -n "$os_version" || source /etc/init.d/base
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 msg_info() {
     echo " # $1"
@@ -8,25 +8,25 @@ msg_info() {
 
 show_iface_ip_addr() {
     addr=$(ip addr show dev $1 2>/dev/null | grep inet | tr -s ' ' | sed -r 's/^\s+//' | cut -d ' ' -f 2)
-    test -n "$addr" && msg_info "Interface $1 has IP address $addr"
+    test -n "${addr}" && msg_info "Interface $1 has IP address ${addr}"
 }
 
 show_gateway() {
     gateway=$(ip route | grep default | cut -d ' ' -f 3)
-    test -n "$gateway" && msg_info "Default gateway is $gateway"
+    test -n "${gateway}" && msg_info "Default gateway is ${gateway}"
 }
 
 show_dns() {
     test -r /etc/resolv.conf || return
     dns=$(cat /etc/resolv.conf | grep nameserver | head -n 1 | cut -d ' ' -f 2)
-    test -n "$dns" && msg_info "DNS server address is $dns"
+    test -n "${dns}" && msg_info "DNS server address is ${dns}"
 }
 
 case "$1" in
     start)
-        show_iface_ip_addr $os_eth
-        show_iface_ip_addr $os_wlan
-        show_iface_ip_addr $os_ppp
+        show_iface_ip_addr ${OS_ETH}
+        show_iface_ip_addr ${OS_WLAN}
+        show_iface_ip_addr ${OS_PPP}
         show_gateway
         show_dns
         ;;
diff --git a/board/common/overlay/etc/init.d/base b/board/common/overlay/etc/init.d/base
old mode 100755
new mode 100644
index 7b08c9384d..5119498a04
--- a/board/common/overlay/etc/init.d/base
+++ b/board/common/overlay/etc/init.d/base
@@ -1,13 +1,13 @@
-#!/bin/bash
 
 source /etc/version
-board_sn=$(/etc/init.d/boardsn)
-board_name=$(cat /etc/board)
+BOARD_SN=$(/etc/init.d/boardsn)
+BOARD_NAME=$(cat /etc/board)
 
-test -n "$os_debug" || source /etc/init.d/conf
+test -n "${OS_DEBUG}" || source /etc/init.d/os_conf
 
 source /etc/init.d/panic
 
+
 msg_begin() {
     echo -n " * $1: "
 }
@@ -24,3 +24,38 @@ msg_background() {
     test -n "$1" && echo $1 || echo "pending"
 }
 
+prepare_conf() {
+    # $1 - actual config file
+    # $2 - system-provided config file
+    # $3 - user-provided config file
+    
+    # long story short:
+    #  * user conf file takes precedence, if present
+    #  * system conf file is used by default, if actual file absent
+    
+    actual_conf="$1"
+    system_conf="$2"
+    user_conf="$3"
+    
+    if [[ -n "${user_conf}" && -e "${user_conf}" ]]; then
+        cp -rf "${user_conf}" "${actual_conf}"
+        
+        # we want only Unix newlines in conf files
+        if [[ -f "${actual_conf}" ]]; then
+            sed -i 's/\r//g' "${actual_conf}"
+        elif [[ -d "${actual_conf}" ]]; then
+            find "${actual_conf}" -type f | xargs -L1 sed -i 's/\r//g'
+        fi
+        
+        grep -E "/boot .*ro[\s,]" /proc/mounts &>/dev/null
+        RO=$?
+        test ${RO} == 0 && mount -o remount,rw /boot
+        rm -rf ${user_conf}
+        test ${RO} == 0 && mount -o remount,ro /boot
+    fi
+
+    if [[ ! -e "${actual_conf}" && -e "${system_conf}" ]]; then
+        cp "${system_conf}" "${actual_conf}"
+    fi
+}
+
diff --git a/board/common/overlay/etc/init.d/bootdone b/board/common/overlay/etc/init.d/bootdone
index 14ca681cfc..38e16f566b 100755
--- a/board/common/overlay/etc/init.d/bootdone
+++ b/board/common/overlay/etc/init.d/bootdone
@@ -3,5 +3,5 @@
 source /etc/init.d/panic
 
 # reset panic counter after a successful boot
-echo 0 > ${_PANIC_COUNTER_FILE}
+echo 0 > ${PANIC_COUNTER_FILE}
 
diff --git a/board/common/overlay/etc/init.d/conf b/board/common/overlay/etc/init.d/conf
deleted file mode 100644
index 46ab1a6378..0000000000
--- a/board/common/overlay/etc/init.d/conf
+++ /dev/null
@@ -1,29 +0,0 @@
-#!/bin/bash
-
-_sys_conf="/etc/os.conf"
-_boot_conf="/boot/os.conf"
-_conf="/data/etc/os.conf"
-
-if ! [[ -d /data/etc ]]; then
-    # use boot/system variants if we don't have the data partition mounted
-    if [[ -f $_boot_conf ]]; then
-        source $_boot_conf
-    elif [[ -f $_sys_conf ]]; then
-        source $_sys_conf
-    fi
-
-    return
-fi
-
-if ! [[ -f $_conf ]]; then
-    if [[ -f $_boot_conf ]]; then
-        cp $_boot_conf $_conf
-    elif [[ -f $_sys_conf ]]; then
-        cp $_sys_conf $_conf
-    fi
-fi
-
-if [[ -f $_conf ]]; then
-    source $_conf
-fi
-
diff --git a/board/common/overlay/etc/init.d/os_conf b/board/common/overlay/etc/init.d/os_conf
new file mode 100644
index 0000000000..e2f6f6fd58
--- /dev/null
+++ b/board/common/overlay/etc/init.d/os_conf
@@ -0,0 +1,21 @@
+
+_SYS_CONF="/etc/os.conf"
+_BOOT_CONF="/boot/os.conf"
+_DATA_CONF="/data/etc/os.conf"
+
+
+# source in all conf files in order of precedence
+if [[ -f ${_SYS_CONF} ]]; then
+    source ${_SYS_CONF}
+fi
+
+if [[ -f ${_DATA_CONF} ]]; then
+    source ${_DATA_CONF}
+fi
+
+if [[ -f ${_BOOT_CONF} ]]; then
+    source ${_BOOT_CONF}
+fi
+
+unset _SYS_CONF _BOOT_CONF _DATA_CONF
+
diff --git a/board/common/overlay/etc/init.d/panic b/board/common/overlay/etc/init.d/panic
old mode 100755
new mode 100644
index fcf6724e54..4c6c992c20
--- a/board/common/overlay/etc/init.d/panic
+++ b/board/common/overlay/etc/init.d/panic
@@ -1,20 +1,19 @@
-#!/bin/bash
 
-_PANIC_COUNTER_FILE="/var/lib/panic_counter"
-_PANIC_REBOOT_DELAY_FACTOR=10
-_PANIC_REBOOT_DELAY_MAX=3600  # reboot at least once an hour in case of panic
+PANIC_COUNTER_FILE="/var/lib/panic_counter"
+PANIC_REBOOT_DELAY_FACTOR=10
+PANIC_REBOOT_DELAY_MAX=3600  # reboot at least once an hour in case of panic
 
 
 panic_action() {
     # read counter from file
-    panic_counter=$(cat ${_PANIC_COUNTER_FILE} 2>/dev/null || echo 0)
+    panic_counter=$(cat ${PANIC_COUNTER_FILE} 2>/dev/null || echo 0)
     
     # write increased counter back to file
-    echo $((panic_counter + 1)) > ${_PANIC_COUNTER_FILE}
+    echo $((panic_counter + 1)) > ${PANIC_COUNTER_FILE}
     
-    delay=$((_PANIC_REBOOT_DELAY_FACTOR * panic_counter))
-    if [[ "${delay}" -gt "${_PANIC_REBOOT_DELAY_MAX}" ]]; then
-        delay=${_PANIC_REBOOT_DELAY_MAX}
+    delay=$((PANIC_REBOOT_DELAY_FACTOR * panic_counter))
+    if [[ "${delay}" -gt "${PANIC_REBOOT_DELAY_MAX}" ]]; then
+        delay=${PANIC_REBOOT_DELAY_MAX}
     fi
     
     if [[ "${delay}" -gt 0 ]]; then
diff --git a/board/common/overlay/etc/init.d/rcK b/board/common/overlay/etc/init.d/rcK
index 7d08910c5b..0b1d9bd373 100755
--- a/board/common/overlay/etc/init.d/rcK
+++ b/board/common/overlay/etc/init.d/rcK
@@ -1,22 +1,22 @@
 #!/bin/sh
 
-boot_log=/var/log/boot.log
-pid_file=/tmp/rc.pid
+BOOT_LOG=/var/log/boot.log
+PID_FILE=/tmp/rc.pid
 
 source /etc/init.d/base
 
-echo "---- shutting down $os_name $os_version ----" >> $boot_log
+echo "---- shutting down ${OS_NAME} ${OS_VERSION} ----" >> ${BOOT_LOG}
 
 # stop all init scripts in /etc/init.d,
 # executing them in reverse numerical order.
 (for i in $(ls -r /etc/init.d/S??*); do
-    if ! [[ -x "$i" ]]; then continue; fi
-    if [[ -f /data/etc/no_$(basename $i) ]]; then continue; fi
-    $i stop
-done& echo $! > $pid_file) | tee -a $boot_log &
+    if ! [[ -x "${i}" ]]; then continue; fi
+    if [[ -f /data/etc/no_$(basename ${i}) ]]; then continue; fi
+    ${i} stop
+done& echo $! > ${PID_FILE}) | tee -a ${BOOT_LOG} &
 
-pid=$(cat $pid_file)
-while kill -0 $pid 2>/dev/null; do
+pid=$(cat ${PID_FILE})
+while kill -0 ${pid} 2>/dev/null; do
     sleep 1
 done
 
diff --git a/board/common/overlay/etc/init.d/rcS b/board/common/overlay/etc/init.d/rcS
index d15157610f..20c2ce1cd5 100755
--- a/board/common/overlay/etc/init.d/rcS
+++ b/board/common/overlay/etc/init.d/rcS
@@ -1,25 +1,26 @@
 #!/bin/sh
 
-boot_log=/var/log/boot.log
-tmp_boot_log=/tmp/_boot.log
-pid_file=/tmp/rc.pid
+BOOT_LOG=/var/log/boot.log
+TMP_BOOT_LOG=/tmp/_boot.log
+PID_FILE=/tmp/rc.pid
+
 
 source /etc/init.d/base
 
-echo "---- booting $os_name $os_version ----" >> $tmp_boot_log
+echo "---- booting ${OS_NAME} ${OS_VERSION} ----" >> ${TMP_BOOT_LOG}
 
 # start all init scripts in /etc/init.d,
 # executing them in numerical order.
 (for i in /etc/init.d/S??* /etc/init.d/bootdone; do
-    if ! [[ -x "$i" ]]; then continue; fi
-    if [[ -f /data/etc/no_$(basename $i) ]]; then continue; fi
-    $i start || break
-done& echo $! > $pid_file) | tee -a $tmp_boot_log &
+    if ! [[ -x "${i}" ]]; then continue; fi
+    if [[ -f /data/etc/no_$(basename ${i}) ]]; then continue; fi
+    ${i} start || break
+done& echo $! > ${PID_FILE}) | tee -a ${TMP_BOOT_LOG} &
 
-pid=$(cat $pid_file)
-while kill -0 $pid 2>/dev/null; do
+pid=$(cat ${PID_FILE})
+while kill -0 ${pid} 2>/dev/null; do
     sleep 1
 done
 
-test -d $(dirname $boot_log) && cat $tmp_boot_log >> $boot_log
+test -d $(dirname ${BOOT_LOG}) && cat ${TMP_BOOT_LOG} >> ${BOOT_LOG}
 
diff --git a/board/common/overlay/etc/os.conf b/board/common/overlay/etc/os.conf
index 96fff5eb4a..d9b0361c35 100644
--- a/board/common/overlay/etc/os.conf
+++ b/board/common/overlay/etc/os.conf
@@ -1,12 +1,13 @@
-os_debug="false"
-os_prereleases="false"
-os_tty_login="tty1"
-os_eth="eth0"
-os_wlan="wlan0"
-os_ppp="ppp0"
-os_networkless="false"
-os_country="GB"
-os_firmware_method="github"
-os_firmware_repo="ccrisan/thingos"
-os_firmware_username=""
-os_firmware_password=""
+OS_DEBUG="false"
+OS_PRERELEASES="false"
+OS_TTY_LOGIN="tty1"
+OS_ETH="eth0"
+OS_WLAN="wlan0"
+OS_PPP="ppp0"
+OS_NETWORKLESS="false"
+OS_COUNTRY="GB"
+OS_FIRMWARE_METHOD="github"
+OS_FIRMWARE_REPO="ccrisan/thingos"
+OS_FIRMWARE_USERNAME=""
+OS_FIRMWARE_PASSWORD=""
+
diff --git a/board/common/overlay/etc/ppp/ip-up b/board/common/overlay/etc/ppp/ip-up
index b23b7fb054..904c3307ac 100755
--- a/board/common/overlay/etc/ppp/ip-up
+++ b/board/common/overlay/etc/ppp/ip-up
@@ -2,11 +2,11 @@
 
 resolv_conf=/etc/resolv.conf
 
-echo -n > $resolv_conf
-if [ -n "$DNS1" ]; then
-    echo "nameserver $DNS1" >> $resolv_conf
+echo -n > ${resolv_conf}
+if [ -n "${DNS1}" ]; then
+    echo "nameserver ${DNS1}" >> ${resolv_conf}
 fi
-if [ -n "$DNS2" ]; then
-    echo "nameserver $DNS2" >> $resolv_conf
+if [ -n "${DNS2}" ]; then
+    echo "nameserver ${DNS2}" >> ${resolv_conf}
 fi
 
diff --git a/board/common/overlay/etc/version b/board/common/overlay/etc/version
index b42047004c..6921062dac 100644
--- a/board/common/overlay/etc/version
+++ b/board/common/overlay/etc/version
@@ -1,4 +1,4 @@
-os_name="thingOS"
-os_short_name="thingos"
-os_prefix="thing"
-os_version="unknown"
+OS_NAME="thingOS"
+OS_SHORT_NAME="thingos"
+OS_PREFIX="thing"
+OS_VERSION="unknown"
diff --git a/board/common/overlay/etc/watch.conf b/board/common/overlay/etc/watch.conf
index 5876ccc0af..a9f6cad0d6 100644
--- a/board/common/overlay/etc/watch.conf
+++ b/board/common/overlay/etc/watch.conf
@@ -1,12 +1,12 @@
-link_watch="true"
-link_watch_timeout=20
+LINK_WATCH="true"
+LINK_WATCH_TIMEOUT=20
 
-ip_watch="true"
-ip_watch_timeout=40
+IP_WATCH="true"
+IP_WATCH_TIMEOUT=40
 
-#netwatch_host=www.google.com
-#netwatch_port=80
-netwatch_retries=3
-netwatch_timeout=5
-netwatch_interval=20
+#NETWATCH_HOST=www.google.com
+#NETWATCH_PORT=80
+NETWATCH_RETRIES=3
+NETWATCH_TIMEOUT=5
+NETWATCH_INTERVAL=20
 
diff --git a/board/common/overlay/sbin/fwupdate b/board/common/overlay/sbin/fwupdate
index ea3bfeb0f6..4e66f01bb5 100755
--- a/board/common/overlay/sbin/fwupdate
+++ b/board/common/overlay/sbin/fwupdate
@@ -35,7 +35,6 @@ fi
 
 SYS_VERSION_FILE=/etc/version
 SYS_BOARD_FILE=/etc/board
-OS_CONF=/data/etc/os.conf
 
 MIN_FREE_DISK=$((500*1024))  # 500 MB
 VER_FILE=version
@@ -65,12 +64,12 @@ DD_PID_FILE=dd.pid
 BOOT_DEV=$(mount | grep /boot | cut -d ' ' -f 1)
 ROOT_DEV=${BOOT_DEV:0:-1}2
 DISK_DEV=$(mount | grep /boot | cut -d ' ' -f 1)
-if [[ "$ROOT_DEV" =~ ^([/a-z0-9]+)(p[0-9])$ ]]; then  # e.g. /dev/mmcblk0p2
+if [[ "${ROOT_DEV}" =~ ^([/a-z0-9]+)(p[0-9])$ ]]; then  # e.g. /dev/mmcblk0p2
     DISK_DEV=${BASH_REMATCH[1]}
-elif [[ "$ROOT_DEV" =~ ^([/a-z0-9]+)([0-9])$ ]]; then  # e.g. /dev/sdc2
+elif [[ "${ROOT_DEV}" =~ ^([/a-z0-9]+)([0-9])$ ]]; then  # e.g. /dev/sdc2
     DISK_DEV=${BASH_REMATCH[1]}
 else
-    echo "cannot identify disk device from $ROOT_DEV" 1>&2
+    echo "cannot identify disk device from ${ROOT_DEV}" 1>&2
     exit 1
 fi
 
@@ -78,28 +77,29 @@ fi
 #### versions ####
 
 function show_versions() {
-    source $OS_CONF
-    board=$(cat $SYS_BOARD_FILE)
+    source /etc/init.d/os_conf  # we need this for the OS_ vars
+    
+    board=$(cat ${SYS_BOARD_FILE})
     show_json=$1
   
     # the /usr/libexec/list-versions-* helpers return a table with the following format:
     #     <version>|<prerelease>|<board>|<url>|<date>
-    versions=$(FW_USERNAME=$os_firmware_username FW_PASSWORD=$os_firmware_password \
-               /usr/libexec/list-versions-$os_firmware_method $os_firmware_repo)
+    versions=$(FW_USERNAME=${OS_FIRMWARE_USERNAME} FW_PASSWORD=${OS_FIRMWARE_PASSWORD} \
+               /usr/libexec/list-versions-${OS_FIRMWARE_METHOD} ${OS_FIRMWARE_REPO})
 
     for version in ${versions[@]}; do
-        OIFS=$IFS
+        OIFS=${IFS}
         IFS="|"
-        varr=($version)
-        IFS=$OIFS
-        if [ "$os_prereleases" == "false" ] && [ "${varr[1]}" == "true" ]; then
+        varr=(${version})
+        IFS=${OIFS}
+        if [ "${OS_PRERELEASES}" == "false" ] && [ "${varr[1]}" == "true" ]; then
             continue  # skip prereleases
         fi
-        if [ "$board" != "${varr[2]}" ]; then
+        if [ "${board}" != "${varr[2]}" ]; then
             continue  # skip other boards
         fi
 
-        if [ "$show_json" == "true" ]; then
+        if [ "${show_json}" == "true" ]; then
             echo "{\"version\": \"${varr[0]}\"," \
                   "\"url\": \"${varr[3]}\"," \
                   "\"board\": \"${varr[2]}\"," \
@@ -112,9 +112,9 @@ function show_versions() {
 }
 
 function show_current() {
-    source $SYS_VERSION_FILE
+    source ${SYS_VERSION_FILE}
     
-    echo $os_version
+    echo ${OS_VERSION}
 }
 
 
@@ -123,8 +123,8 @@ function show_current() {
 function do_download() {
     echo "downloading..."
 
-    rm -rf $FW_DIR/*
-    mkdir -p $FW_DIR
+    rm -rf ${FW_DIR}/*
+    mkdir -p ${FW_DIR}
 
     # Look for local file first
     if [ -f "$1" ]; then
@@ -132,74 +132,75 @@ function do_download() {
         FNAME=`basename $1`
         FILEEXT=${FNAME##*.}
         DST_FNAME=""
-        if [ "$FILEEXT" == "xz" ]; then
-            DST_FNAME="$FW_DIR/$FW_FILE_XZ"
-        elif [ "$FILEEXT" == "gz" ]; then
-            DST_FNAME="$FW_DIR/$FW_FILE_GZ"
+        if [ "${FILEEXT}" == "xz" ]; then
+            DST_FNAME="${FW_DIR}/${FW_FILE_XZ}"
+        elif [ "${FILEEXT}" == "gz" ]; then
+            DST_FNAME="${FW_DIR}/${FW_FILE_GZ}"
         fi
-        if [ -n "$DST_FNAME" ]; then
-            cp -f $1 $DST_FNAME
-            echo $version > $FW_DIR/$VER_FILE
+        if [ -n "${DST_FNAME}" ]; then
+            cp -f $1 ${DST_FNAME}
+            echo ${version} > ${FW_DIR}/${VER_FILE}
             return
         fi
     fi
 
-    source $OS_CONF
-    board=$(cat $SYS_BOARD_FILE)
+    source /etc/init.d/os_conf  # we need this for the OS_ vars
+    
+    board=$(cat ${SYS_BOARD_FILE})
     url=$1
     version=$1
 
-    if ! [[ "$url" == http* ]]; then  # a version was given
-        url=$(show_versions true | jq -r ". | select(.version==\"$version\") | .url")
+    if ! [[ "${url}" == http* ]]; then  # a version was given
+        url=$(show_versions true | jq -r ". | select(.version==\"${version}\") | .url")
     else
         version="custom"
     fi
 
-    if [ -z "$url" ]; then
+    if [ -z "${url}" ]; then
         echo "no such version" 1>&2
         exit 1
     fi
 
     free_disk=$(df /data | tail -n 1 | tr -s ' ' | cut -d ' ' -f 4)
-    if [ "$free_disk" -lt $MIN_FREE_DISK ]; then
+    if [ "${free_disk}" -lt ${MIN_FREE_DISK} ]; then
         echo "not enough disk space" 1>&2
         exit 1
     fi
 
-    outfile=$FW_DIR/$FW_FILE_GZ
-    format=$(echo $url | sed -rn 's/.*\.img\.([a-z]+)$/\1/ p')
-    if [ "$format" == "xz" ]; then
-        outfile=$FW_DIR/$FW_FILE_XZ
+    outfile=${FW_DIR}/${FW_FILE_GZ}
+    format=$(echo ${url} | sed -rn 's/.*\.img\.([a-z]+)$/\1/ p')
+    if [ "${format}" == "xz" ]; then
+        outfile=${FW_DIR}/${FW_FILE_XZ}
     fi
 
-    echo $version > $FW_DIR/$VER_FILE
+    echo ${version} > ${FW_DIR}/${VER_FILE}
 
     curl_opts="-S -f -L"
-    if [ -n "$os_firmware_username" ]; then
-        curl_opts+=" --user $os_firmware_username:$os_firmware_password"
+    if [ -n "${OS_FIRMWARE_USERNAME}" ]; then
+        curl_opts+=" --user ${OS_FIRMWARE_USERNAME}:${OS_FIRMWARE_PASSWORD}"
     fi
 
-    curl $curl_opts -o $outfile "$url" &> $FW_DIR/$CURL_LOG_FILE &
+    curl ${curl_opts} -o ${outfile} "${url}" &> ${FW_DIR}/${CURL_LOG_FILE} &
     pid=$!
-    echo $pid > $FW_DIR/$CURL_PID_FILE
-    wait $pid
+    echo ${pid} > ${FW_DIR}/${CURL_PID_FILE}
+    wait ${pid}
     
     if [ "$?" != 0 ]; then
-        cat $FW_DIR/$CURL_LOG_FILE
+        cat ${FW_DIR}/${CURL_LOG_FILE}
         exit 1
     fi
 }
 
 function download_status() {
-    if [ -f $FW_DIR/$CURL_PID_FILE ]; then
-        pid=$(cat $FW_DIR/$CURL_PID_FILE)
-        if kill -0 $pid &>/dev/null; then
+    if [ -f ${FW_DIR}/${CURL_PID_FILE} ]; then
+        pid=$(cat ${FW_DIR}/${CURL_PID_FILE})
+        if kill -0 ${pid} &>/dev/null; then
             echo "running"
             return
         fi
     fi
 
-    if [ -f $FW_DIR/$FW_FILE_GZ -o -f $FW_DIR/$FW_FILE_XZ ]; then
+    if [ -f ${FW_DIR}/${FW_FILE_GZ} -o -f ${FW_DIR}/${FW_FILE_XZ} ]; then
         echo "done"
     fi
 }
@@ -210,69 +211,69 @@ function download_status() {
 function do_extract() {
     echo "extracting..."
     
-    rm -f $FW_DIR/$FW_FILE_EXTR
-    rm -f $FW_DIR/$BOOT_READY_FILE
+    rm -f ${FW_DIR}/${FW_FILE_EXTR}
+    rm -f ${FW_DIR}/${BOOT_READY_FILE}
 
-    if ! [ -f $FW_DIR/$FW_FILE_GZ -o -f $FW_DIR/$FW_FILE_XZ ]; then
+    if ! [ -f ${FW_DIR}/${FW_FILE_GZ} -o -f ${FW_DIR}/${FW_FILE_XZ} ]; then
         echo "firmware file not downloaded" 1>&2
         exit 1
     fi
 
     format="gz"
-    if [ -f $FW_DIR/$FW_FILE_XZ ]; then
+    if [ -f ${FW_DIR}/${FW_FILE_XZ} ]; then
         format="xz"
     fi
 
-    rm -f $FW_DIR/$FW_FILE_EXTR
-    rm -f $FW_DIR/$GUNZIP_PID_FILE $FW_DIR/$XZCAT_PID_FILE
+    rm -f ${FW_DIR}/${FW_FILE_EXTR}
+    rm -f ${FW_DIR}/${GUNZIP_PID_FILE} ${FW_DIR}/${XZCAT_PID_FILE}
 
-    if [ "$format" == "xz" ]; then
-        DECOMPRESS_LOG_FILE=$FW_DIR/$XZCAT_LOG_FILE
-        DECOMPRESS_PID_FILE=$FW_DIR/$XZCAT_PID_FILE
-        xzcat $FW_DIR/$FW_FILE_XZ > $FW_DIR/$FW_FILE_EXTR 2>$FW_DIR/$XZCAT_LOG_FILE &
-    elif [ "$format" == "gz" ]; then
-        DECOMPRESS_LOG_FILE=$FW_DIR/$GUNZIP_LOG_FILE
-        DECOMPRESS_PID_FILE=$FW_DIR/$GUNZIP_PID_FILE
-        gunzip -k -c $FW_DIR/$FW_FILE_GZ > $FW_DIR/$FW_FILE_EXTR 2>$FW_DIR/$GUNZIP_LOG_FILE &
+    if [ "${format}" == "xz" ]; then
+        DECOMPRESS_LOG_FILE=${FW_DIR}/${XZCAT_LOG_FILE}
+        DECOMPRESS_PID_FILE=${FW_DIR}/${XZCAT_PID_FILE}
+        xzcat ${FW_DIR}/${FW_FILE_XZ} > ${FW_DIR}/${FW_FILE_EXTR} 2>${FW_DIR}/${XZCAT_LOG_FILE} &
+    elif [ "${format}" == "gz" ]; then
+        DECOMPRESS_LOG_FILE=${FW_DIR}/${GUNZIP_LOG_FILE}
+        DECOMPRESS_PID_FILE=${FW_DIR}/${GUNZIP_PID_FILE}
+        gunzip -k -c ${FW_DIR}/${FW_FILE_GZ} > ${FW_DIR}/${FW_FILE_EXTR} 2>${FW_DIR}/${GUNZIP_LOG_FILE} &
     else
-        echo "firmware compression format $format not supported" 1>&2
+        echo "firmware compression format ${format} not supported" 1>&2
         exit 1
     fi
     
     pid=$!
-    echo $pid > $DECOMPRESS_PID_FILE
-    wait $pid
+    echo ${pid} > ${DECOMPRESS_PID_FILE}
+    wait ${pid}
 
     if [ "$?" != 0 ]; then
-        cat $DECOMPRESS_LOG_FILE
+        cat ${DECOMPRESS_LOG_FILE}
         exit 1
     fi
     
     # verify available partition space
     
-    fw_boot_info=$(fdisk --bytes -l -o device,start,end,size $FW_DIR/$FW_FILE_EXTR | grep "${FW_FILE_EXTR}1")
-    fw_boot_info=($fw_boot_info)
+    fw_boot_info=$(fdisk --bytes -l -o device,start,end,size ${FW_DIR}/${FW_FILE_EXTR} | grep "${FW_FILE_EXTR}1")
+    fw_boot_info=(${fw_boot_info})
     fw_boot_size=${fw_boot_info[3]}
 
-    fw_root_info=$(fdisk --bytes -l -o device,start,end,size $FW_DIR/$FW_FILE_EXTR | grep "${FW_FILE_EXTR}2")
-    fw_root_info=($fw_root_info)
+    fw_root_info=$(fdisk --bytes -l -o device,start,end,size ${FW_DIR}/${FW_FILE_EXTR} | grep "${FW_FILE_EXTR}2")
+    fw_root_info=(${fw_root_info})
     fw_root_size=${fw_root_info[3]}
     
-    disk_boot_info=$(fdisk --bytes -l -o device,start,end,size $DISK_DEV | grep $BOOT_DEV)
-    disk_boot_info=($disk_boot_info)
+    disk_boot_info=$(fdisk --bytes -l -o device,start,end,size ${DISK_DEV} | grep ${BOOT_DEV})
+    disk_boot_info=(${disk_boot_info})
     disk_boot_size=${disk_boot_info[3]}
     
-    disk_root_info=$(fdisk --bytes -l -o device,start,end,size $DISK_DEV | grep $ROOT_DEV)
-    disk_root_info=($disk_root_info)
+    disk_root_info=$(fdisk --bytes -l -o device,start,end,size ${DISK_DEV} | grep ${ROOT_DEV})
+    disk_root_info=(${disk_root_info})
     disk_root_size=${disk_root_info[3]}
     
-    if [[ $disk_boot_size -lt $fw_boot_size ]]; then
-        echo "not enough space on boot partition ($fw_boot_size needed, $disk_boot_size available)" 1>&2
+    if [[ ${disk_boot_size} -lt ${fw_boot_size} ]]; then
+        echo "not enough space on boot partition (${fw_boot_size} needed, ${disk_boot_size} available)" 1>&2
         exit 1
     fi
 
-    if [[ $disk_root_size -lt $fw_root_size ]]; then
-        echo "not enough space on root partition ($fw_root_size needed, $disk_root_size available)" 1>&2
+    if [[ ${disk_root_size} -lt ${fw_root_size} ]]; then
+        echo "not enough space on root partition (${fw_root_size} needed, ${disk_root_size} available)" 1>&2
         exit 1
     fi
 
@@ -280,21 +281,21 @@ function do_extract() {
 }
 
 function extract_status() {
-    if [ -f $FW_DIR/$XZCAT_PID_FILE ]; then
-        pid=$(cat $FW_DIR/$XZCAT_PID_FILE)
-        if kill -0 $pid &>/dev/null; then
+    if [ -f ${FW_DIR}/${XZCAT_PID_FILE} ]; then
+        pid=$(cat ${FW_DIR}/${XZCAT_PID_FILE})
+        if kill -0 ${pid} &>/dev/null; then
             echo "running"
             return
         fi
-    elif [ -f $FW_DIR/$GUNZIP_PID_FILE ]; then
-        pid=$(cat $FW_DIR/$GUNZIP_PID_FILE)
-        if kill -0 $pid &>/dev/null; then
+    elif [ -f ${FW_DIR}/${GUNZIP_PID_FILE} ]; then
+        pid=$(cat ${FW_DIR}/${GUNZIP_PID_FILE})
+        if kill -0 ${pid} &>/dev/null; then
             echo "running"
             return
         fi
     fi
 
-    if [ -f $FW_DIR/$FW_FILE_EXTR ]; then
+    if [ -f ${FW_DIR}/${FW_FILE_EXTR} ]; then
         echo "done"
     fi
 }
@@ -305,12 +306,12 @@ function extract_status() {
 function flash_boot() {
     echo "flashing boot..."
     
-    rm -f $FW_DIR/$BOOT_READY_FILE
+    rm -f ${FW_DIR}/${BOOT_READY_FILE}
 
     set +e
-    board=$(cat $SYS_BOARD_FILE)
+    board=$(cat ${SYS_BOARD_FILE})
 
-    cp -r /boot $FW_DIR/old_boot
+    cp -r /boot ${FW_DIR}/old_boot
     umount /boot
     trap flash_cleanup EXIT
 
@@ -318,22 +319,22 @@ function flash_boot() {
     mv /sbin/reboot /sbin/reboot.bak
     ln -s /bin/true /sbin/reboot
     
-    boot_info=$(fdisk --bytes -l -o device,start,end,size $FW_DIR/$FW_FILE_EXTR | grep "${FW_FILE_EXTR}1")
-    boot_info=($boot_info)
+    boot_info=$(fdisk --bytes -l -o device,start,end,size ${FW_DIR}/${FW_FILE_EXTR} | grep "${FW_FILE_EXTR}1")
+    boot_info=(${boot_info})
     boot_start=$((${boot_info[1]} / 2048))  # in MB
     boot_size=$((${boot_info[3]} / 1048576))  # in MB
 
-    root_info=$(fdisk --bytes -l -o device,start,end,size $FW_DIR/$FW_FILE_EXTR | grep "${FW_FILE_EXTR}2")
-    root_info=($root_info)
+    root_info=$(fdisk --bytes -l -o device,start,end,size ${FW_DIR}/${FW_FILE_EXTR} | grep "${FW_FILE_EXTR}2")
+    root_info=(${root_info})
     root_start=$((${root_info[1]} / 2048))  # in MB
     root_size=$((${root_info[3]} / 1048576))  # in MB
     
-    echo $root_start $root_size > $FW_DIR/$ROOT_INFO_FILE
+    echo ${root_start} ${root_size} > ${FW_DIR}/${ROOT_INFO_FILE}
 
-    dd if=$FW_DIR/$FW_FILE_EXTR skip=$boot_start of=$BOOT_DEV bs=1048576 count=$boot_size &>$FW_DIR/$DD_LOG_FILE &
+    dd if=${FW_DIR}/${FW_FILE_EXTR} skip=${boot_start} of=${BOOT_DEV} bs=1048576 count=${boot_size} &>${FW_DIR}/${DD_LOG_FILE} &
     pid=$!
-    echo $pid > $FW_DIR/$DD_PID_FILE
-    wait $pid
+    echo ${pid} > ${FW_DIR}/${DD_PID_FILE}
+    wait ${pid}
 
     mount -T /etc/fstab.disk -o rw /boot
     
@@ -341,21 +342,21 @@ function flash_boot() {
     # and should restore any /boot configuration that needs to be preserved across updates
     # from the old boot dir to the current (new) /boot dir
     if [ -x /usr/libexec/fw-restore-boot-cfg ]; then
-        /usr/libexec/fw-restore-boot-cfg $FW_DIR/old_boot 2>/dev/null || true
+        /usr/libexec/fw-restore-boot-cfg ${FW_DIR}/old_boot 2>/dev/null || true
     fi
-    touch $FW_DIR/$BOOT_READY_FILE
+    touch ${FW_DIR}/${BOOT_READY_FILE}
 }
 
 function flash_boot_status() {
-    if [ -f $FW_DIR/$DD_PID_FILE ]; then
-        pid=$(cat $FW_DIR/$DD_PID_FILE)
-        if kill -0 $pid &>/dev/null; then
+    if [ -f ${FW_DIR}/${DD_PID_FILE} ]; then
+        pid=$(cat ${FW_DIR}/${DD_PID_FILE})
+        if kill -0 ${pid} &>/dev/null; then
             echo "running"
             return
         fi
     fi
 
-    if [ -f $FW_DIR/$BOOT_READY_FILE ]; then
+    if [ -f ${FW_DIR}/${BOOT_READY_FILE} ]; then
         echo "done"
     fi
 }
@@ -375,7 +376,7 @@ function flash_cleanup() {
 function flash_reboot() {
     echo "preparing for reboot..."
 
-    board=$(cat $SYS_BOARD_FILE)
+    board=$(cat ${SYS_BOARD_FILE})
     
     # the /usr/libexec/fw-prepare-boot script should be present and should
     # make the necessary changes to the current boot configuration so that
@@ -398,28 +399,28 @@ function flash_reboot() {
 
 function show_status() {
     status=$(flash_boot_status)
-    if [ "$status" == "running" ]; then
+    if [ "${status}" == "running" ]; then
         echo "flashing boot $(new_version)"
         return
-    elif [ "$status" == "done" ]; then
+    elif [ "${status}" == "done" ]; then
         echo "boot ready $(new_version)"
         return
     fi
 
     status=$(extract_status)
-    if [ "$status" == "running" ]; then
+    if [ "${status}" == "running" ]; then
         echo "extracting $(new_version)"
         return
-    elif [ "$status" == "done" ]; then
+    elif [ "${status}" == "done" ]; then
         echo "extracted $(new_version)"
         return
     fi
     
     status=$(download_status)
-    if [ "$status" == "running" ]; then
+    if [ "${status}" == "running" ]; then
         echo "downloading $(new_version)"
         return
-    elif [ -n "$status" ]; then
+    elif [ -n "${status}" ]; then
         echo "downloaded $(new_version)"
         return
     fi
@@ -449,7 +450,7 @@ function do_upgrade() {
 
 
 function new_version() {
-    cat $FW_DIR/$VER_FILE
+    cat ${FW_DIR}/${VER_FILE}
 }
 
 
@@ -457,7 +458,7 @@ case "$1" in
     versions)
         show_json="false"
         test "$2" == "-j" && show_json="true"
-        show_versions $show_json
+        show_versions ${show_json}
         ;;
 
     current)
diff --git a/board/common/overlay/usr/bin/gpio.sh b/board/common/overlay/usr/bin/gpio.sh
index c291e7c6c8..aaa62843de 100755
--- a/board/common/overlay/usr/bin/gpio.sh
+++ b/board/common/overlay/usr/bin/gpio.sh
@@ -7,14 +7,14 @@ usage() {
     exit 1
 }
 
-test -z "$GPIO" && usage
-test -e /sys/class/gpio/gpio$GPIO || echo $GPIO > /sys/class/gpio/export
+test -z "${GPIO}" && usage
+test -e /sys/class/gpio/gpio${GPIO} || echo ${GPIO} > /sys/class/gpio/export
 
 if [ -n "$2" ]; then
-    echo out > /sys/class/gpio/gpio$GPIO/direction
-    echo $2 > /sys/class/gpio/gpio$GPIO/value
+    echo out > /sys/class/gpio/gpio${GPIO}/direction
+    echo $2 > /sys/class/gpio/gpio${GPIO}/value
 else
-    echo in > /sys/class/gpio/gpio$GPIO/direction
-    cat /sys/class/gpio/gpio$GPIO/value
+    echo in > /sys/class/gpio/gpio${GPIO}/direction
+    cat /sys/class/gpio/gpio${GPIO}/value
 fi
 
diff --git a/board/common/overlay/usr/libexec/list-versions-bitbucket b/board/common/overlay/usr/libexec/list-versions-bitbucket
index f11b796185..6f1d7fb9f3 100755
--- a/board/common/overlay/usr/libexec/list-versions-bitbucket
+++ b/board/common/overlay/usr/libexec/list-versions-bitbucket
@@ -7,22 +7,22 @@ fi
 
 function check_prerelease() {
     read line
-    if [[ "$line" =~ ^[0-9._]+\| ]]; then
-        echo "$line"
+    if [[ "${line}" =~ ^[0-9._]+\| ]]; then
+        echo "${line}"
     else
-        echo "$line" | sed 's/|false|/|true|/'
+        echo "${line}" | sed 's/|false|/|true|/'
     fi
 }
 
 extensions=".img.gz .img.xz .img"
 opts="-s -S -f"
-test -n "$FW_USERNAME" && opts+=" --user $FW_USERNAME:$FW_PASSWORD"
+test -n "${FW_USERNAME}" && opts+=" --user ${FW_USERNAME}:${FW_PASSWORD}"
 url="https://api.bitbucket.org/2.0/repositories/$1/downloads?pagelen=100&_=$(date +%s)"
 
-rtrimstr=$(for e in $extensions; do echo -n " | rtrimstr(\"$e\")"; done)
+rtrimstr=$(for e in ${extensions}; do echo -n " | rtrimstr(\"${e}\")"; done)
 jq_expr=".values[] | [{a: .name | split(\"-\"), url: .links.self.href, date: .created_on | split(\"T\")[0]}] |
-         map((.a[2] $rtrimstr), \"false\", .a[1], .url, .date) | join(\"|\")"
+         map((.a[2] ${rtrimstr}), \"false\", .a[1], .url, .date) | join(\"|\")"
 
-curl $opts $url | jq --raw-output "$jq_expr" | while read line; do echo "$line" | check_prerelease; done
+curl ${opts} ${url} | jq --raw-output "${jq_expr}" | while read line; do echo "${line}" | check_prerelease; done
 exit ${PIPESTATUS[0]}
 
diff --git a/board/common/overlay/usr/libexec/list-versions-github b/board/common/overlay/usr/libexec/list-versions-github
index f5b1d64197..8ac8b0e356 100755
--- a/board/common/overlay/usr/libexec/list-versions-github
+++ b/board/common/overlay/usr/libexec/list-versions-github
@@ -6,13 +6,13 @@ if [ -z "$1" ]; then
 fi
 
 opts="-s -S -f"
-test -n "$FW_USERNAME" && opts+=" --user $FW_USERNAME:$FW_PASSWORD"
+test -n "${FW_USERNAME}" && opts+=" --user ${FW_USERNAME}:${FW_PASSWORD}"
 url=https://api.github.com/repos/$1/releases
 
 jq_expr='.[] | {version: .name, prerelease: .prerelease | tostring} + 
          (.assets[] | {name: .name | split("-")[1], url: .browser_download_url}) + 
          ({date: .created_at | split("T")[0]}) | flatten | join("|")'
 
-curl $opts $url | jq --raw-output "$jq_expr"
+curl ${opts} ${url} | jq --raw-output "${jq_expr}"
 exit ${PIPESTATUS[0]}
 
diff --git a/board/common/overlay/usr/sbin/adminpasswd b/board/common/overlay/usr/sbin/adminpasswd
index 8779fead1d..a5c2cbccfc 100755
--- a/board/common/overlay/usr/sbin/adminpasswd
+++ b/board/common/overlay/usr/sbin/adminpasswd
@@ -23,8 +23,8 @@ rm -f /data/etc/shadow-
 
 # set root and admin passwords (admin is just an alias for root)
 
-echo -en "$PASSWORD\n$PASSWORD\n" | passwd -a md5 &>/dev/null # root
-echo -en "$PASSWORD\n$PASSWORD\n" | passwd -a md5 admin &>/dev/null # admin
+echo -en "${PASSWORD}\n${PASSWORD}\n" | passwd -a md5 &>/dev/null # root
+echo -en "${PASSWORD}\n${PASSWORD}\n" | passwd -a md5 admin &>/dev/null # admin
 
 sed -r -i 's/root:([^:]+):[[:digit:]]+:/root:\1::/' /data/etc/shadow # removes pwd expiration
 sed -r -i 's/admin:([^:]+):[[:digit:]]+:/admin:\1::/' /data/etc/shadow # removes pwd expiration
@@ -32,7 +32,7 @@ sed -r -i 's/admin:([^:]+):[[:digit:]]+:/admin:\1::/' /data/etc/shadow # removes
 # call admin password hooks in /etc/adminpasswd.d
 if [ -d /etc/adminpasswd.d ]; then
     for script in /etc/adminpasswd.d/*; do
-        test -x $script && $script
+        test -x ${script} && ${script}
     done
 fi
 
diff --git a/board/common/postscript.sh b/board/common/postscript.sh
index f315019cdd..a10cee1305 100755
--- a/board/common/postscript.sh
+++ b/board/common/postscript.sh
@@ -3,50 +3,50 @@
 set -e
 
 export TARGET="$1"
-export BOARD=$(basename $(dirname $TARGET))
+export BOARD=$(basename $(dirname ${TARGET}))
 export COMMON_DIR=$(dirname $0)
-export BOARD_DIR=$COMMON_DIR/../$BOARD
-export BOOT_DIR=$TARGET/../images/boot/
-export IMG_DIR=$TARGET/../images
+export BOARD_DIR=${COMMON_DIR}/../${BOARD}
+export BOOT_DIR=${TARGET}/../images/boot/
+export IMG_DIR=${TARGET}/../images
 
-mkdir -p $BOOT_DIR
+mkdir -p ${BOOT_DIR}
 
-if [ -x $BOARD_DIR/postscript.sh ]; then
-    $BOARD_DIR/postscript.sh
+if [ -x ${BOARD_DIR}/postscript.sh ]; then
+    ${BOARD_DIR}/postscript.sh
 fi
 
 # cleanups
-$COMMON_DIR/cleanups.sh
-if [ -x $BOARD_DIR/cleanups.sh ]; then
-    $BOARD_DIR/cleanups.sh
+${COMMON_DIR}/cleanups.sh
+if [ -x ${BOARD_DIR}/cleanups.sh ]; then
+    ${BOARD_DIR}/cleanups.sh
 fi
 
 # transform /var contents as needed
-rm -rf $TARGET/var/cache
-rm -rf $TARGET/var/lib
-rm -rf $TARGET/var/lock
-rm -rf $TARGET/var/log
-rm -rf $TARGET/var/run
-rm -rf $TARGET/var/spool
-rm -rf $TARGET/var/tmp
+rm -rf ${TARGET}/var/cache
+rm -rf ${TARGET}/var/lib
+rm -rf ${TARGET}/var/lock
+rm -rf ${TARGET}/var/log
+rm -rf ${TARGET}/var/run
+rm -rf ${TARGET}/var/spool
+rm -rf ${TARGET}/var/tmp
 
-ln -s /tmp $TARGET/var/cache
-ln -s /data/varlib $TARGET/var/lib
-ln -s /tmp $TARGET/var/lock
-ln -s /data/log $TARGET/var/log
-ln -s /tmp $TARGET/var/run
-ln -s /tmp $TARGET/var/spool
-ln -s /tmp $TARGET/var/tmp
-ln -s /tmp $TARGET/run
+ln -s /tmp ${TARGET}/var/cache
+ln -s /data/varlib ${TARGET}/var/lib
+ln -s /tmp ${TARGET}/var/lock
+ln -s /data/log ${TARGET}/var/log
+ln -s /tmp ${TARGET}/var/run
+ln -s /tmp ${TARGET}/var/spool
+ln -s /tmp ${TARGET}/var/tmp
+ln -s /tmp ${TARGET}/run
 
 # board-specific os.conf
-if [ -r $BOARD_DIR/os.conf ]; then
-    for line in $(cat $BOARD_DIR/os.conf); do
-        key=$(echo $line | cut -d '=' -f 1)
-        sed -i -r "s/$key=.*/$line/" /$TARGET/etc/os.conf
+if [ -r ${BOARD_DIR}/os.conf ]; then
+    for line in $(cat ${BOARD_DIR}/os.conf); do
+        key=$(echo ${line} | cut -d '=' -f 1)
+        sed -i -r "s/${key}=.*/${line}/" /${TARGET}/etc/os.conf
     done
 fi
 
 # add admin user alias
-echo "admin:x:0:0:root:/root:/bin/sh" >> $TARGET/etc/passwd
+echo "admin:x:0:0:root:/root:/bin/sh" >> ${TARGET}/etc/passwd
 
diff --git a/board/nanopineo/cpinitramfs.sh b/board/nanopineo/cpinitramfs.sh
index 7c5af3f0e4..6b79ac324c 100755
--- a/board/nanopineo/cpinitramfs.sh
+++ b/board/nanopineo/cpinitramfs.sh
@@ -1,4 +1,4 @@
 #!/bin/bash
 
-cp $IMG_DIR/rootfs.cpio.uboot $BOARD_DIR/uInitrd
+cp ${IMG_DIR}/rootfs.cpio.uboot ${BOARD_DIR}/uInitrd
 
diff --git a/board/nanopineo/mkimage.sh b/board/nanopineo/mkimage.sh
index ad35c4810e..60c5170a55 100755
--- a/board/nanopineo/mkimage.sh
+++ b/board/nanopineo/mkimage.sh
@@ -1,13 +1,13 @@
 #!/bin/bash -e
 
 BOARD_DIR=$(dirname $0)
-COMMON_DIR=$BOARD_DIR/../common
+COMMON_DIR=${BOARD_DIR}/../common
 
-export BOARD=$(basename $BOARD_DIR)
-export IMG_DIR=$BOARD_DIR/../../output/$BOARD/images/
-export UBOOT_BIN=$BOARD_DIR/u-boot-with-spl.bin
+export BOARD=$(basename ${BOARD_DIR})
+export IMG_DIR=${BOARD_DIR}/../../output/${BOARD}/images/
+export UBOOT_BIN=${BOARD_DIR}/u-boot-with-spl.bin
 export UBOOT_SEEK=16
 export BOOT_START=20
-source $COMMON_DIR/mkimage.sh
+source ${COMMON_DIR}/mkimage.sh
 
 
diff --git a/board/nanopineo/os.conf b/board/nanopineo/os.conf
index dc77b07e6d..bbfeece44c 100644
--- a/board/nanopineo/os.conf
+++ b/board/nanopineo/os.conf
@@ -1,2 +1,2 @@
-os_tty_login="ttyS0"
+OS_TTY_LOGIN="ttyS0"
 
diff --git a/board/nanopineo/postscript.sh b/board/nanopineo/postscript.sh
index 48f12d845a..913b6e0760 100755
--- a/board/nanopineo/postscript.sh
+++ b/board/nanopineo/postscript.sh
@@ -2,10 +2,10 @@
 
 set -e
 
-$HOST_DIR/bin/mkimage -C none -A arm -T script -d $BOARD_DIR/boot.cmd $BOOT_DIR/boot.scr
-$HOST_DIR/bin/mkimage -C none -A arm -T script -d $BOARD_DIR/boot-fwupdater.cmd $BOOT_DIR/boot-fwupdater.scr
+${HOST_DIR}/bin/mkimage -C none -A arm -T script -d ${BOARD_DIR}/boot.cmd ${BOOT_DIR}/boot.scr
+${HOST_DIR}/bin/mkimage -C none -A arm -T script -d ${BOARD_DIR}/boot-fwupdater.cmd ${BOOT_DIR}/boot-fwupdater.scr
 
-cp $IMG_DIR/zImage $BOOT_DIR
-cp $BOARD_DIR/sun8i-h3-nanopi-neo.dtb $BOOT_DIR
-cp $BOARD_DIR/rootfs.cpio.uboot $BOOT_DIR
+cp ${IMG_DIR}/zImage ${BOOT_DIR}
+cp ${BOARD_DIR}/sun8i-h3-nanopi-neo.dtb ${BOOT_DIR}
+cp ${BOARD_DIR}/rootfs.cpio.uboot ${BOOT_DIR}
 
diff --git a/board/nanopineo2/cpinitramfs.sh b/board/nanopineo2/cpinitramfs.sh
index 7c5af3f0e4..6b79ac324c 100755
--- a/board/nanopineo2/cpinitramfs.sh
+++ b/board/nanopineo2/cpinitramfs.sh
@@ -1,4 +1,4 @@
 #!/bin/bash
 
-cp $IMG_DIR/rootfs.cpio.uboot $BOARD_DIR/uInitrd
+cp ${IMG_DIR}/rootfs.cpio.uboot ${BOARD_DIR}/uInitrd
 
diff --git a/board/nanopineo2/mkimage.sh b/board/nanopineo2/mkimage.sh
index ad35c4810e..60c5170a55 100755
--- a/board/nanopineo2/mkimage.sh
+++ b/board/nanopineo2/mkimage.sh
@@ -1,13 +1,13 @@
 #!/bin/bash -e
 
 BOARD_DIR=$(dirname $0)
-COMMON_DIR=$BOARD_DIR/../common
+COMMON_DIR=${BOARD_DIR}/../common
 
-export BOARD=$(basename $BOARD_DIR)
-export IMG_DIR=$BOARD_DIR/../../output/$BOARD/images/
-export UBOOT_BIN=$BOARD_DIR/u-boot-with-spl.bin
+export BOARD=$(basename ${BOARD_DIR})
+export IMG_DIR=${BOARD_DIR}/../../output/${BOARD}/images/
+export UBOOT_BIN=${BOARD_DIR}/u-boot-with-spl.bin
 export UBOOT_SEEK=16
 export BOOT_START=20
-source $COMMON_DIR/mkimage.sh
+source ${COMMON_DIR}/mkimage.sh
 
 
diff --git a/board/nanopineo2/os.conf b/board/nanopineo2/os.conf
index dc77b07e6d..bbfeece44c 100644
--- a/board/nanopineo2/os.conf
+++ b/board/nanopineo2/os.conf
@@ -1,2 +1,2 @@
-os_tty_login="ttyS0"
+OS_TTY_LOGIN="ttyS0"
 
diff --git a/board/nanopineo2/postscript.sh b/board/nanopineo2/postscript.sh
index c86407b13e..91996d8ac1 100755
--- a/board/nanopineo2/postscript.sh
+++ b/board/nanopineo2/postscript.sh
@@ -2,10 +2,10 @@
 
 set -e
 
-$HOST_DIR/bin/mkimage -C none -A arm -T script -d $BOARD_DIR/boot.cmd $BOOT_DIR/boot.scr
-$HOST_DIR/bin/mkimage -C none -A arm -T script -d $BOARD_DIR/boot-fwupdater.cmd $BOOT_DIR/boot-fwupdater.scr
+${HOST_DIR}/bin/mkimage -C none -A arm -T script -d ${BOARD_DIR}/boot.cmd ${BOOT_DIR}/boot.scr
+${HOST_DIR}/bin/mkimage -C none -A arm -T script -d ${BOARD_DIR}/boot-fwupdater.cmd ${BOOT_DIR}/boot-fwupdater.scr
 
-cp $IMG_DIR/Image $BOOT_DIR
-cp $BOARD_DIR/sun50i-h5-nanopi-neo2.dtb $BOOT_DIR
-cp $BOARD_DIR/rootfs.cpio.uboot $BOOT_DIR
+cp ${IMG_DIR}/Image ${BOOT_DIR}
+cp ${BOARD_DIR}/sun50i-h5-nanopi-neo2.dtb ${BOOT_DIR}
+cp ${BOARD_DIR}/rootfs.cpio.uboot ${BOOT_DIR}
 
diff --git a/board/odroidc1/cpinitramfs.sh b/board/odroidc1/cpinitramfs.sh
index 7c5af3f0e4..6b79ac324c 100755
--- a/board/odroidc1/cpinitramfs.sh
+++ b/board/odroidc1/cpinitramfs.sh
@@ -1,4 +1,4 @@
 #!/bin/bash
 
-cp $IMG_DIR/rootfs.cpio.uboot $BOARD_DIR/uInitrd
+cp ${IMG_DIR}/rootfs.cpio.uboot ${BOARD_DIR}/uInitrd
 
diff --git a/board/odroidc1/mkimage.sh b/board/odroidc1/mkimage.sh
index 3c8d0af446..df30d7ab96 100755
--- a/board/odroidc1/mkimage.sh
+++ b/board/odroidc1/mkimage.sh
@@ -1,16 +1,16 @@
 #!/bin/bash -e
 
 BOARD_DIR=$(dirname $0)
-COMMON_DIR=$BOARD_DIR/../common
+COMMON_DIR=${BOARD_DIR}/../common
 
-export BOARD=$(basename $BOARD_DIR)
-export IMG_DIR=$BOARD_DIR/../../output/$BOARD/images/
-export UBOOT_BIN=$IMG_DIR/u-boot.bin
+export BOARD=$(basename ${BOARD_DIR})
+export IMG_DIR=${BOARD_DIR}/../../output/${BOARD}/images/
+export UBOOT_BIN=${IMG_DIR}/u-boot.bin
 export UBOOT_SEEK=64
-BL1=$IMG_DIR/bl1.bin.hardkernel
+BL1=${IMG_DIR}/bl1.bin.hardkernel
 
-source $COMMON_DIR/mkimage.sh
+source ${COMMON_DIR}/mkimage.sh
 
-dd conv=notrunc if=$BL1 of=$DISK_IMG bs=1 count=442
-dd conv=notrunc if=$BL1 of=$DISK_IMG bs=512 skip=1 seek=1
+dd conv=notrunc if=${BL1} of=${DISK_IMG} bs=1 count=442
+dd conv=notrunc if=${BL1} of=${DISK_IMG} bs=512 skip=1 seek=1
 
diff --git a/board/odroidc1/os.conf b/board/odroidc1/os.conf
index dc77b07e6d..bbfeece44c 100644
--- a/board/odroidc1/os.conf
+++ b/board/odroidc1/os.conf
@@ -1,2 +1,2 @@
-os_tty_login="ttyS0"
+OS_TTY_LOGIN="ttyS0"
 
diff --git a/board/odroidc1/postscript.sh b/board/odroidc1/postscript.sh
index ccf44bb4e0..8261cc1275 100755
--- a/board/odroidc1/postscript.sh
+++ b/board/odroidc1/postscript.sh
@@ -3,23 +3,23 @@
 set -e
 
 # boot directory
-mkdir -p $BOOT_DIR
+mkdir -p ${BOOT_DIR}
 
-cp $IMG_DIR/uImage $BOOT_DIR
-cp $IMG_DIR/meson8b_odroidc.dtb $BOOT_DIR
-cp $BOARD_DIR/bl1.bin.hardkernel $IMG_DIR
-cp $BOARD_DIR/u-boot.bin $IMG_DIR
-cp $BOARD_DIR/boot.ini $BOOT_DIR
-cp $BOARD_DIR/uInitrd $BOOT_DIR
+cp ${IMG_DIR}/uImage ${BOOT_DIR}
+cp ${IMG_DIR}/meson8b_odroidc.dtb ${BOOT_DIR}
+cp ${BOARD_DIR}/bl1.bin.hardkernel ${IMG_DIR}
+cp ${BOARD_DIR}/u-boot.bin ${IMG_DIR}
+cp ${BOARD_DIR}/boot.ini ${BOOT_DIR}
+cp ${BOARD_DIR}/uInitrd ${BOOT_DIR}
 
 # fix some lib dirs
-if ! [ -L $TARGET/lib/arm-linux-gnueabihf ]; then
-    mv $TARGET/lib/arm-linux-gnueabihf/* $TARGET/lib
-    rmdir $TARGET/lib/arm-linux-gnueabihf
-    ln -s /lib $TARGET/lib/arm-linux-gnueabihf
+if ! [ -L ${TARGET}/lib/arm-linux-gnueabihf ]; then
+    mv ${TARGET}/lib/arm-linux-gnueabihf/* ${TARGET}/lib
+    rmdir ${TARGET}/lib/arm-linux-gnueabihf
+    ln -s /lib ${TARGET}/lib/arm-linux-gnueabihf
 fi
 
-if ! [ -L $TARGET/usr/lib/arm-linux-gnueabihf ]; then
-    ln -s /usr/lib $TARGET/usr/lib/arm-linux-gnueabihf
+if ! [ -L ${TARGET}/usr/lib/arm-linux-gnueabihf ]; then
+    ln -s /usr/lib ${TARGET}/usr/lib/arm-linux-gnueabihf
 fi
 
diff --git a/board/odroidc2/cpinitramfs.sh b/board/odroidc2/cpinitramfs.sh
index 7c5af3f0e4..6b79ac324c 100755
--- a/board/odroidc2/cpinitramfs.sh
+++ b/board/odroidc2/cpinitramfs.sh
@@ -1,4 +1,4 @@
 #!/bin/bash
 
-cp $IMG_DIR/rootfs.cpio.uboot $BOARD_DIR/uInitrd
+cp ${IMG_DIR}/rootfs.cpio.uboot ${BOARD_DIR}/uInitrd
 
diff --git a/board/odroidc2/mkimage.sh b/board/odroidc2/mkimage.sh
index 39e8b5f230..aaf47fd7fc 100755
--- a/board/odroidc2/mkimage.sh
+++ b/board/odroidc2/mkimage.sh
@@ -1,16 +1,16 @@
 #!/bin/bash -e
 
 BOARD_DIR=$(dirname $0)
-COMMON_DIR=$BOARD_DIR/../common
+COMMON_DIR=${BOARD_DIR}/../common
 
-export BOARD=$(basename $BOARD_DIR)
-export IMG_DIR=$BOARD_DIR/../../output/$BOARD/images/
-export UBOOT_BIN=$IMG_DIR/u-boot.bin
+export BOARD=$(basename ${BOARD_DIR})
+export IMG_DIR=${BOARD_DIR}/../../output/${BOARD}/images/
+export UBOOT_BIN=${IMG_DIR}/u-boot.bin
 export UBOOT_SEEK=97
-BL1=$IMG_DIR/bl1.bin.hardkernel
+BL1=${IMG_DIR}/bl1.bin.hardkernel
 
-source $COMMON_DIR/mkimage.sh
+source ${COMMON_DIR}/mkimage.sh
 
-dd conv=notrunc if=$BL1 of=$DISK_IMG bs=1 count=442
-dd conv=notrunc if=$BL1 of=$DISK_IMG bs=512 skip=1 seek=1
+dd conv=notrunc if=${BL1} of=${DISK_IMG} bs=1 count=442
+dd conv=notrunc if=${BL1} of=${DISK_IMG} bs=512 skip=1 seek=1
 
diff --git a/board/odroidc2/os.conf b/board/odroidc2/os.conf
index dc77b07e6d..bbfeece44c 100644
--- a/board/odroidc2/os.conf
+++ b/board/odroidc2/os.conf
@@ -1,2 +1,2 @@
-os_tty_login="ttyS0"
+OS_TTY_LOGIN="ttyS0"
 
diff --git a/board/odroidc2/postscript.sh b/board/odroidc2/postscript.sh
index 0296849600..68aa180144 100755
--- a/board/odroidc2/postscript.sh
+++ b/board/odroidc2/postscript.sh
@@ -3,12 +3,12 @@
 set -e
 
 # boot directory
-mkdir -p $BOOT_DIR
+mkdir -p ${BOOT_DIR}
 
-cp $IMG_DIR/Image $BOOT_DIR
-cp $IMG_DIR/meson64_odroidc2.dtb $BOOT_DIR
-cp $BOARD_DIR/bl1.bin.hardkernel $IMG_DIR
-cp $BOARD_DIR/u-boot.bin $IMG_DIR
-cp $BOARD_DIR/boot.ini $BOOT_DIR
-cp $BOARD_DIR/uInitrd $BOOT_DIR
+cp ${IMG_DIR}/Image ${BOOT_DIR}
+cp ${IMG_DIR}/meson64_odroidc2.dtb ${BOOT_DIR}
+cp ${BOARD_DIR}/bl1.bin.hardkernel ${IMG_DIR}
+cp ${BOARD_DIR}/u-boot.bin ${IMG_DIR}
+cp ${BOARD_DIR}/boot.ini ${BOOT_DIR}
+cp ${BOARD_DIR}/uInitrd ${BOOT_DIR}
 
diff --git a/board/odroidxu4/cpinitramfs.sh b/board/odroidxu4/cpinitramfs.sh
index 7c5af3f0e4..6b79ac324c 100755
--- a/board/odroidxu4/cpinitramfs.sh
+++ b/board/odroidxu4/cpinitramfs.sh
@@ -1,4 +1,4 @@
 #!/bin/bash
 
-cp $IMG_DIR/rootfs.cpio.uboot $BOARD_DIR/uInitrd
+cp ${IMG_DIR}/rootfs.cpio.uboot ${BOARD_DIR}/uInitrd
 
diff --git a/board/odroidxu4/mkimage.sh b/board/odroidxu4/mkimage.sh
index 409d891605..aefe63b134 100755
--- a/board/odroidxu4/mkimage.sh
+++ b/board/odroidxu4/mkimage.sh
@@ -1,19 +1,19 @@
 #!/bin/bash -e
 
 BOARD_DIR=$(dirname $0)
-COMMON_DIR=$BOARD_DIR/../common
+COMMON_DIR=${BOARD_DIR}/../common
 
-export BOARD=$(basename $BOARD_DIR)
-export IMG_DIR=$BOARD_DIR/../../output/$BOARD/images/
-export UBOOT_BIN=$IMG_DIR/u-boot.bin
+export BOARD=$(basename ${BOARD_DIR})
+export IMG_DIR=${BOARD_DIR}/../../output/${BOARD}/images/
+export UBOOT_BIN=${IMG_DIR}/u-boot.bin
 export UBOOT_SEEK=63
-BL1=$IMG_DIR/bl1.bin.hardkernel
-BL2=$IMG_DIR/bl2.bin.hardkernel
-TZSW=$IMG_DIR/tzsw.bin.hardkernel
-source $COMMON_DIR/mkimage.sh
+BL1=${IMG_DIR}/bl1.bin.hardkernel
+BL2=${IMG_DIR}/bl2.bin.hardkernel
+TZSW=${IMG_DIR}/tzsw.bin.hardkernel
+source ${COMMON_DIR}/mkimage.sh
 
-dd conv=notrunc if=$BL1 of=$DISK_IMG bs=512 seek=1
-dd conv=notrunc if=$BL2 of=$DISK_IMG bs=512 seek=31
-dd conv=notrunc if=$TZSW of=$DISK_IMG bs=512 seek=719
-dd conv=notrunc if=/dev/zero of=$DISK_IMG bs=512 seek=1231 count=32
+dd conv=notrunc if=${BL1} of=${DISK_IMG} bs=512 seek=1
+dd conv=notrunc if=${BL2} of=${DISK_IMG} bs=512 seek=31
+dd conv=notrunc if=${TZSW} of=${DISK_IMG} bs=512 seek=719
+dd conv=notrunc if=/dev/zero of=${DISK_IMG} bs=512 seek=1231 count=32
 
diff --git a/board/odroidxu4/overlay/etc/init.d/S02waiteth b/board/odroidxu4/overlay/etc/init.d/S02waiteth
index 6873243889..5088e50eb9 100755
--- a/board/odroidxu4/overlay/etc/init.d/S02waiteth
+++ b/board/odroidxu4/overlay/etc/init.d/S02waiteth
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-test -n "$os_version" || source /etc/init.d/base
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 case "$1" in
     start)
diff --git a/board/odroidxu4/postscript.sh b/board/odroidxu4/postscript.sh
index 1a965ae5c8..22749d3b2f 100755
--- a/board/odroidxu4/postscript.sh
+++ b/board/odroidxu4/postscript.sh
@@ -3,15 +3,15 @@
 set -e
 
 # boot directory
-mkdir -p $BOOT_DIR
+mkdir -p ${BOOT_DIR}
 
-cp $BOARD_DIR/bl1.bin.hardkernel $IMG_DIR
-cp $BOARD_DIR/bl2.bin.hardkernel $IMG_DIR
-cp $BOARD_DIR/tzsw.bin.hardkernel $IMG_DIR
-cp $BOARD_DIR/u-boot.bin $IMG_DIR
+cp ${BOARD_DIR}/bl1.bin.hardkernel ${IMG_DIR}
+cp ${BOARD_DIR}/bl2.bin.hardkernel ${IMG_DIR}
+cp ${BOARD_DIR}/tzsw.bin.hardkernel ${IMG_DIR}
+cp ${BOARD_DIR}/u-boot.bin ${IMG_DIR}
 
-cp $IMG_DIR/zImage $BOOT_DIR
-cp $IMG_DIR/exynos5422-odroidxu4.dtb $BOOT_DIR
-cp $BOARD_DIR/boot.ini $BOOT_DIR
-cp $BOARD_DIR/uInitrd $BOOT_DIR
+cp ${IMG_DIR}/zImage ${BOOT_DIR}
+cp ${IMG_DIR}/exynos5422-odroidxu4.dtb ${BOOT_DIR}
+cp ${BOARD_DIR}/boot.ini ${BOOT_DIR}
+cp ${BOARD_DIR}/uInitrd ${BOOT_DIR}
 
diff --git a/board/orangepione/cpinitramfs.sh b/board/orangepione/cpinitramfs.sh
index 7c5af3f0e4..6b79ac324c 100755
--- a/board/orangepione/cpinitramfs.sh
+++ b/board/orangepione/cpinitramfs.sh
@@ -1,4 +1,4 @@
 #!/bin/bash
 
-cp $IMG_DIR/rootfs.cpio.uboot $BOARD_DIR/uInitrd
+cp ${IMG_DIR}/rootfs.cpio.uboot ${BOARD_DIR}/uInitrd
 
diff --git a/board/orangepione/mkimage.sh b/board/orangepione/mkimage.sh
index b4e6ff16d9..2e53952649 100755
--- a/board/orangepione/mkimage.sh
+++ b/board/orangepione/mkimage.sh
@@ -1,13 +1,13 @@
 #!/bin/bash -e
 
 BOARD_DIR=$(dirname $0)
-COMMON_DIR=$BOARD_DIR/../common
+COMMON_DIR=${BOARD_DIR}/../common
 
-export BOARD=$(basename $BOARD_DIR)
-export IMG_DIR=$BOARD_DIR/../../output/$BOARD/images/
-export UBOOT_BIN=$IMG_DIR/u-boot-sunxi-with-spl.bin
+export BOARD=$(basename ${BOARD_DIR})
+export IMG_DIR=${BOARD_DIR}/../../output/${BOARD}/images/
+export UBOOT_BIN=${IMG_DIR}/u-boot-sunxi-with-spl.bin
 export UBOOT_SEEK=16
 export BOOT_START=20
-source $COMMON_DIR/mkimage.sh
+source ${COMMON_DIR}/mkimage.sh
 
 
diff --git a/board/orangepione/postscript.sh b/board/orangepione/postscript.sh
index 6b2bf27881..f4bfc82c78 100755
--- a/board/orangepione/postscript.sh
+++ b/board/orangepione/postscript.sh
@@ -2,9 +2,9 @@
 
 set -e
 
-$HOST_DIR/bin/mkimage -C none -A arm -T script -d $BOARD_DIR/boot.cmd $BOOT_DIR/boot.scr
-$HOST_DIR/bin/mkimage -C none -A arm -T script -d $BOARD_DIR/boot-fwupdater.cmd $BOOT_DIR/boot-fwupdater.scr
+${HOST_DIR}/bin/mkimage -C none -A arm -T script -d ${BOARD_DIR}/boot.cmd ${BOOT_DIR}/boot.scr
+${HOST_DIR}/bin/mkimage -C none -A arm -T script -d ${BOARD_DIR}/boot-fwupdater.cmd ${BOOT_DIR}/boot-fwupdater.scr
 
-cp $IMG_DIR/zImage $BOOT_DIR
-cp $IMG_DIR/sun8i-h3-orangepi-one.dtb $BOOT_DIR
-cp $BOARD_DIR/rootfs.cpio.uboot $BOOT_DIR
+cp ${IMG_DIR}/zImage ${BOOT_DIR}
+cp ${IMG_DIR}/sun8i-h3-orangepi-one.dtb ${BOOT_DIR}
+cp ${BOARD_DIR}/rootfs.cpio.uboot ${BOOT_DIR}
diff --git a/board/pine64/cpinitramfs.sh b/board/pine64/cpinitramfs.sh
index 7c5af3f0e4..6b79ac324c 100755
--- a/board/pine64/cpinitramfs.sh
+++ b/board/pine64/cpinitramfs.sh
@@ -1,4 +1,4 @@
 #!/bin/bash
 
-cp $IMG_DIR/rootfs.cpio.uboot $BOARD_DIR/uInitrd
+cp ${IMG_DIR}/rootfs.cpio.uboot ${BOARD_DIR}/uInitrd
 
diff --git a/board/pine64/mkimage.sh b/board/pine64/mkimage.sh
index d1e83348f9..1cb5440feb 100755
--- a/board/pine64/mkimage.sh
+++ b/board/pine64/mkimage.sh
@@ -1,16 +1,16 @@
 #!/bin/bash -e
 
 BOARD_DIR=$(dirname $0)
-COMMON_DIR=$BOARD_DIR/../common
+COMMON_DIR=${BOARD_DIR}/../common
 
-export BOARD=$(basename $BOARD_DIR)
-export IMG_DIR=$BOARD_DIR/../../output/$BOARD/images/
-export UBOOT_BIN=$BOARD_DIR/u-boot-with-dtb.bin
+export BOARD=$(basename ${BOARD_DIR})
+export IMG_DIR=${BOARD_DIR}/../../output/${BOARD}/images/
+export UBOOT_BIN=${BOARD_DIR}/u-boot-with-dtb.bin
 export UBOOT_SEEK=38192
 export BOOT_START=20
-BOOT0=$BOARD_DIR/boot0.bin
+BOOT0=${BOARD_DIR}/boot0.bin
 
-source $COMMON_DIR/mkimage.sh
+source ${COMMON_DIR}/mkimage.sh
 
-dd conv=notrunc if=$BOOT0 of=$DISK_IMG bs=1k seek=8 count=32 oflag=direct 
+dd conv=notrunc if=${BOOT0} of=${DISK_IMG} bs=1k seek=8 count=32 oflag=direct 
 
diff --git a/board/pine64/postscript.sh b/board/pine64/postscript.sh
index 5e8cc683d1..d106a2323d 100755
--- a/board/pine64/postscript.sh
+++ b/board/pine64/postscript.sh
@@ -3,10 +3,10 @@
 set -e
 
 # boot directory
-mkdir -p $BOOT_DIR/pine64
+mkdir -p ${BOOT_DIR}/pine64
 
-cp $IMG_DIR/Image $BOOT_DIR/kernel.img
-cp $BOARD_DIR/uEnv.txt $BOOT_DIR
-cp $BOARD_DIR/dtb/* $BOOT_DIR/pine64
-cp $BOARD_DIR/fwupdater.img $BOOT_DIR
+cp ${IMG_DIR}/Image ${BOOT_DIR}/kernel.img
+cp ${BOARD_DIR}/uEnv.txt ${BOOT_DIR}
+cp ${BOARD_DIR}/dtb/* ${BOOT_DIR}/pine64
+cp ${BOARD_DIR}/fwupdater.img ${BOOT_DIR}
 
diff --git a/board/raspberrypi/cleanups.sh b/board/raspberrypi/cleanups.sh
index 7e41addaed..81f8694b8a 100755
--- a/board/raspberrypi/cleanups.sh
+++ b/board/raspberrypi/cleanups.sh
@@ -1,5 +1,5 @@
 #!/bin/sh
 
-rm -rf $TARGET/opt/vc/src
-rm -rf $TARGET/opt/vc/include
+rm -rf ${TARGET}/opt/vc/src
+rm -rf ${TARGET}/opt/vc/include
 
diff --git a/board/raspberrypi/cpinitramfs.sh b/board/raspberrypi/cpinitramfs.sh
index ac4e9e8d72..165ff01703 100755
--- a/board/raspberrypi/cpinitramfs.sh
+++ b/board/raspberrypi/cpinitramfs.sh
@@ -1,4 +1,4 @@
 #!/bin/bash
 
-cp $IMG_DIR/rootfs.cpio.gz $BOARD_DIR/fwupdater.gz
+cp ${IMG_DIR}/rootfs.cpio.gz ${BOARD_DIR}/fwupdater.gz
 
diff --git a/board/raspberrypi/mkimage.sh b/board/raspberrypi/mkimage.sh
index 9d0d2dbf71..f09e4b392f 100755
--- a/board/raspberrypi/mkimage.sh
+++ b/board/raspberrypi/mkimage.sh
@@ -1,10 +1,10 @@
 #!/bin/bash -e
 
 BOARD_DIR=$(dirname $0)
-COMMON_DIR=$BOARD_DIR/../common
+COMMON_DIR=${BOARD_DIR}/../common
 
-export BOARD=$(basename $BOARD_DIR)
-export IMG_DIR=$BOARD_DIR/../../output/$BOARD/images/
+export BOARD=$(basename ${BOARD_DIR})
+export IMG_DIR=${BOARD_DIR}/../../output/${BOARD}/images/
 
-$COMMON_DIR/mkimage.sh
+${COMMON_DIR}/mkimage.sh
 
diff --git a/board/raspberrypi/overlay/etc/init.d/S05cpufreq b/board/raspberrypi/overlay/etc/init.d/S05cpufreq
index 82ae420f49..ed1d28f889 100755
--- a/board/raspberrypi/overlay/etc/init.d/S05cpufreq
+++ b/board/raspberrypi/overlay/etc/init.d/S05cpufreq
@@ -1,18 +1,19 @@
 #!/bin/bash
 
-test -n "$os_version" || source /etc/init.d/base
+GOV="ondemand"
+CPUFREQDIR="/sys/devices/system/cpu/cpu0/cpufreq"
+GOVDIR="/sys/devices/system/cpu/cpufreq/${GOV}"
 
-gov="ondemand"
-cpufreqdir="/sys/devices/system/cpu/cpu0/cpufreq"
-govdir="/sys/devices/system/cpu/cpufreq/$gov"
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 configure() {
-    echo $gov > $cpufreqdir/scaling_governor
-    if [[ $gov == "ondemand" ]]; then
-        echo 50 > $govdir/up_threshold
-        echo 100000 > $govdir/sampling_rate
-        echo 50 > $govdir/sampling_down_factor
-        echo 1 > $govdir/io_is_busy
+    echo ${GOV} > ${CPUFREQDIR}/scaling_governor
+    if [[ ${GOV} == "ondemand" ]]; then
+        echo 50 > ${GOVDIR}/up_threshold
+        echo 100000 > ${GOVDIR}/sampling_rate
+        echo 50 > ${GOVDIR}/sampling_down_factor
+        echo 1 > ${GOVDIR}/io_is_busy
     fi
 }
 
diff --git a/board/raspberrypi/overlay/etc/init.d/S11throttlewatch b/board/raspberrypi/overlay/etc/init.d/S11throttlewatch
index a06374158c..4f6a422152 100755
--- a/board/raspberrypi/overlay/etc/init.d/S11throttlewatch
+++ b/board/raspberrypi/overlay/etc/init.d/S11throttlewatch
@@ -1,8 +1,9 @@
 #!/bin/bash
 
-check_interval=30
+CHECK_INTERVAL=30
 
-test -n "$os_version" || source /etc/init.d/base
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 get_throttled_now() {
     t=$(vcgencmd get_throttled | cut -d '=' -f 2)
@@ -21,23 +22,23 @@ get_throttled_since_boot() {
 watch_now() {
     while true; do
         t=$(get_throttled_now)
-        if [[ -n "$t" ]]; then
-            logger -t throttlewatch -s "currently: $t"
+        if [[ -n "${t}" ]]; then
+            logger -t throttlewatch -s "currently: ${t}"
         fi
 
-        sleep $check_interval
+        sleep ${CHECK_INTERVAL}
     done
 }
 
 watch_since_boot() {
     while true; do
         t=$(get_throttled_since_boot)
-        if [[ -n "$t" ]]; then
-            logger -t throttlewatch -s "since boot: $t"
+        if [[ -n "${t}" ]]; then
+            logger -t throttlewatch -s "since boot: ${t}"
             break
         fi
         
-        sleep $check_interval
+        sleep ${CHECK_INTERVAL}
     done
 }
 
diff --git a/board/raspberrypi/overlay/etc/init.d/S13btuart b/board/raspberrypi/overlay/etc/init.d/S13btuart
index f5d51a4148..0ad4deda81 100755
--- a/board/raspberrypi/overlay/etc/init.d/S13btuart
+++ b/board/raspberrypi/overlay/etc/init.d/S13btuart
@@ -1,14 +1,15 @@
 #!/bin/bash
 
-sys_conf="/etc/bluetooth.conf"
-boot_conf="/boot/bluetooth.conf"
-conf="/data/etc/bluetooth.conf"
+SYS_CONF="/etc/bluetooth.conf"
+BOOT_CONF="/boot/bluetooth.conf"
+CONF="/data/etc/bluetooth.conf"
 
-test -f $conf || test -f $boot_conf || test -f $sys_conf || exit 0
+
+test -f ${CONF} || test -f ${BOOT_CONF} || test -f ${SYS_CONF} || exit 0
 
 test -d "/proc/device-tree/soc/gpio@7e200000/uart0_pins" || exit 0  # no rpi bluetooth detected
 
-test -n "$os_version" || source /etc/init.d/base
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 function start() {
     if [[ "$(cat /proc/device-tree/aliases/uart0)" = "$(cat /proc/device-tree/aliases/serial1)" ]] ; then
diff --git a/board/raspberrypi/overlay/usr/libexec/fw-restore-boot-cfg b/board/raspberrypi/overlay/usr/libexec/fw-restore-boot-cfg
index 628189ebf6..a4cf5afe76 100755
--- a/board/raspberrypi/overlay/usr/libexec/fw-restore-boot-cfg
+++ b/board/raspberrypi/overlay/usr/libexec/fw-restore-boot-cfg
@@ -6,5 +6,5 @@ if [ -z "$1" ]; then
 fi
 
 old_boot=$1
-cp $old_boot/config.txt /boot
+cp ${old_boot}/config.txt /boot
 
diff --git a/board/raspberrypi/postscript.sh b/board/raspberrypi/postscript.sh
index 31683c5e03..c87c51c422 100755
--- a/board/raspberrypi/postscript.sh
+++ b/board/raspberrypi/postscript.sh
@@ -2,17 +2,17 @@
 
 set -e
 
-RPI_FW_DIR=$TARGET/../images/rpi-firmware
+RPI_FW_DIR=${TARGET}/../images/rpi-firmware
 
-cp $BOARD_DIR/config.txt $BOOT_DIR
-cp $BOARD_DIR/cmdline.txt $BOOT_DIR
-cp $BOARD_DIR/fwupdater.gz $BOOT_DIR
-cp $IMG_DIR/zImage $BOOT_DIR/kernel.img
-cp $IMG_DIR/bcm2708-rpi-b.dtb $BOOT_DIR
-cp $IMG_DIR/bcm2708-rpi-b-plus.dtb $BOOT_DIR
-cp $IMG_DIR/bcm2708-rpi-cm.dtb $BOOT_DIR
-cp $IMG_DIR/bcm2708-rpi-0-w.dtb $BOOT_DIR
-cp $RPI_FW_DIR/bootcode.bin $BOOT_DIR
-cp $RPI_FW_DIR/start.elf $BOOT_DIR
-cp $RPI_FW_DIR/fixup.dat $BOOT_DIR
+cp ${BOARD_DIR}/config.txt ${BOOT_DIR}
+cp ${BOARD_DIR}/cmdline.txt ${BOOT_DIR}
+cp ${BOARD_DIR}/fwupdater.gz ${BOOT_DIR}
+cp ${IMG_DIR}/zImage ${BOOT_DIR}/kernel.img
+cp ${IMG_DIR}/bcm2708-rpi-b.dtb ${BOOT_DIR}
+cp ${IMG_DIR}/bcm2708-rpi-b-plus.dtb ${BOOT_DIR}
+cp ${IMG_DIR}/bcm2708-rpi-cm.dtb ${BOOT_DIR}
+cp ${IMG_DIR}/bcm2708-rpi-0-w.dtb ${BOOT_DIR}
+cp ${RPI_FW_DIR}/bootcode.bin ${BOOT_DIR}
+cp ${RPI_FW_DIR}/start.elf ${BOOT_DIR}
+cp ${RPI_FW_DIR}/fixup.dat ${BOOT_DIR}
 
diff --git a/board/raspberrypi2/overlay/etc/init.d/S05cpufreq b/board/raspberrypi2/overlay/etc/init.d/S05cpufreq
index 82ae420f49..ed1d28f889 100755
--- a/board/raspberrypi2/overlay/etc/init.d/S05cpufreq
+++ b/board/raspberrypi2/overlay/etc/init.d/S05cpufreq
@@ -1,18 +1,19 @@
 #!/bin/bash
 
-test -n "$os_version" || source /etc/init.d/base
+GOV="ondemand"
+CPUFREQDIR="/sys/devices/system/cpu/cpu0/cpufreq"
+GOVDIR="/sys/devices/system/cpu/cpufreq/${GOV}"
 
-gov="ondemand"
-cpufreqdir="/sys/devices/system/cpu/cpu0/cpufreq"
-govdir="/sys/devices/system/cpu/cpufreq/$gov"
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 configure() {
-    echo $gov > $cpufreqdir/scaling_governor
-    if [[ $gov == "ondemand" ]]; then
-        echo 50 > $govdir/up_threshold
-        echo 100000 > $govdir/sampling_rate
-        echo 50 > $govdir/sampling_down_factor
-        echo 1 > $govdir/io_is_busy
+    echo ${GOV} > ${CPUFREQDIR}/scaling_governor
+    if [[ ${GOV} == "ondemand" ]]; then
+        echo 50 > ${GOVDIR}/up_threshold
+        echo 100000 > ${GOVDIR}/sampling_rate
+        echo 50 > ${GOVDIR}/sampling_down_factor
+        echo 1 > ${GOVDIR}/io_is_busy
     fi
 }
 
diff --git a/board/raspberrypi2/overlay/etc/init.d/S11throttlewatch b/board/raspberrypi2/overlay/etc/init.d/S11throttlewatch
index a06374158c..4f6a422152 100755
--- a/board/raspberrypi2/overlay/etc/init.d/S11throttlewatch
+++ b/board/raspberrypi2/overlay/etc/init.d/S11throttlewatch
@@ -1,8 +1,9 @@
 #!/bin/bash
 
-check_interval=30
+CHECK_INTERVAL=30
 
-test -n "$os_version" || source /etc/init.d/base
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 get_throttled_now() {
     t=$(vcgencmd get_throttled | cut -d '=' -f 2)
@@ -21,23 +22,23 @@ get_throttled_since_boot() {
 watch_now() {
     while true; do
         t=$(get_throttled_now)
-        if [[ -n "$t" ]]; then
-            logger -t throttlewatch -s "currently: $t"
+        if [[ -n "${t}" ]]; then
+            logger -t throttlewatch -s "currently: ${t}"
         fi
 
-        sleep $check_interval
+        sleep ${CHECK_INTERVAL}
     done
 }
 
 watch_since_boot() {
     while true; do
         t=$(get_throttled_since_boot)
-        if [[ -n "$t" ]]; then
-            logger -t throttlewatch -s "since boot: $t"
+        if [[ -n "${t}" ]]; then
+            logger -t throttlewatch -s "since boot: ${t}"
             break
         fi
         
-        sleep $check_interval
+        sleep ${CHECK_INTERVAL}
     done
 }
 
diff --git a/board/raspberrypi2/overlay/usr/libexec/fw-restore-boot-cfg b/board/raspberrypi2/overlay/usr/libexec/fw-restore-boot-cfg
index 628189ebf6..a4cf5afe76 100755
--- a/board/raspberrypi2/overlay/usr/libexec/fw-restore-boot-cfg
+++ b/board/raspberrypi2/overlay/usr/libexec/fw-restore-boot-cfg
@@ -6,5 +6,5 @@ if [ -z "$1" ]; then
 fi
 
 old_boot=$1
-cp $old_boot/config.txt /boot
+cp ${old_boot}/config.txt /boot
 
diff --git a/board/raspberrypi2/postscript.sh b/board/raspberrypi2/postscript.sh
index bb556320bd..e3d49b2fab 100755
--- a/board/raspberrypi2/postscript.sh
+++ b/board/raspberrypi2/postscript.sh
@@ -2,14 +2,14 @@
 
 set -e
 
-RPI_FW_DIR=$TARGET/../images/rpi-firmware
+RPI_FW_DIR=${TARGET}/../images/rpi-firmware
 
-cp $BOARD_DIR/config.txt $BOOT_DIR
-cp $BOARD_DIR/cmdline.txt $BOOT_DIR
-cp $BOARD_DIR/fwupdater.gz $BOOT_DIR
-cp $IMG_DIR/zImage $BOOT_DIR/kernel.img
-cp $IMG_DIR/bcm2709-rpi-2-b.dtb $BOOT_DIR
-cp $RPI_FW_DIR/bootcode.bin $BOOT_DIR
-cp $RPI_FW_DIR/start.elf $BOOT_DIR
-cp $RPI_FW_DIR/fixup.dat $BOOT_DIR
+cp ${BOARD_DIR}/config.txt ${BOOT_DIR}
+cp ${BOARD_DIR}/cmdline.txt ${BOOT_DIR}
+cp ${BOARD_DIR}/fwupdater.gz ${BOOT_DIR}
+cp ${IMG_DIR}/zImage ${BOOT_DIR}/kernel.img
+cp ${IMG_DIR}/bcm2709-rpi-2-b.dtb ${BOOT_DIR}
+cp ${RPI_FW_DIR}/bootcode.bin ${BOOT_DIR}
+cp ${RPI_FW_DIR}/start.elf ${BOOT_DIR}
+cp ${RPI_FW_DIR}/fixup.dat ${BOOT_DIR}
 
diff --git a/board/raspberrypi3/overlay/etc/init.d/S05cpufreq b/board/raspberrypi3/overlay/etc/init.d/S05cpufreq
index 82ae420f49..ed1d28f889 100755
--- a/board/raspberrypi3/overlay/etc/init.d/S05cpufreq
+++ b/board/raspberrypi3/overlay/etc/init.d/S05cpufreq
@@ -1,18 +1,19 @@
 #!/bin/bash
 
-test -n "$os_version" || source /etc/init.d/base
+GOV="ondemand"
+CPUFREQDIR="/sys/devices/system/cpu/cpu0/cpufreq"
+GOVDIR="/sys/devices/system/cpu/cpufreq/${GOV}"
 
-gov="ondemand"
-cpufreqdir="/sys/devices/system/cpu/cpu0/cpufreq"
-govdir="/sys/devices/system/cpu/cpufreq/$gov"
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 configure() {
-    echo $gov > $cpufreqdir/scaling_governor
-    if [[ $gov == "ondemand" ]]; then
-        echo 50 > $govdir/up_threshold
-        echo 100000 > $govdir/sampling_rate
-        echo 50 > $govdir/sampling_down_factor
-        echo 1 > $govdir/io_is_busy
+    echo ${GOV} > ${CPUFREQDIR}/scaling_governor
+    if [[ ${GOV} == "ondemand" ]]; then
+        echo 50 > ${GOVDIR}/up_threshold
+        echo 100000 > ${GOVDIR}/sampling_rate
+        echo 50 > ${GOVDIR}/sampling_down_factor
+        echo 1 > ${GOVDIR}/io_is_busy
     fi
 }
 
diff --git a/board/raspberrypi3/overlay/etc/init.d/S11throttlewatch b/board/raspberrypi3/overlay/etc/init.d/S11throttlewatch
index a06374158c..4f6a422152 100755
--- a/board/raspberrypi3/overlay/etc/init.d/S11throttlewatch
+++ b/board/raspberrypi3/overlay/etc/init.d/S11throttlewatch
@@ -1,8 +1,9 @@
 #!/bin/bash
 
-check_interval=30
+CHECK_INTERVAL=30
 
-test -n "$os_version" || source /etc/init.d/base
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 get_throttled_now() {
     t=$(vcgencmd get_throttled | cut -d '=' -f 2)
@@ -21,23 +22,23 @@ get_throttled_since_boot() {
 watch_now() {
     while true; do
         t=$(get_throttled_now)
-        if [[ -n "$t" ]]; then
-            logger -t throttlewatch -s "currently: $t"
+        if [[ -n "${t}" ]]; then
+            logger -t throttlewatch -s "currently: ${t}"
         fi
 
-        sleep $check_interval
+        sleep ${CHECK_INTERVAL}
     done
 }
 
 watch_since_boot() {
     while true; do
         t=$(get_throttled_since_boot)
-        if [[ -n "$t" ]]; then
-            logger -t throttlewatch -s "since boot: $t"
+        if [[ -n "${t}" ]]; then
+            logger -t throttlewatch -s "since boot: ${t}"
             break
         fi
         
-        sleep $check_interval
+        sleep ${CHECK_INTERVAL}
     done
 }
 
diff --git a/board/raspberrypi3/overlay/etc/init.d/S13btuart b/board/raspberrypi3/overlay/etc/init.d/S13btuart
index 513842ba6a..0ad4deda81 100755
--- a/board/raspberrypi3/overlay/etc/init.d/S13btuart
+++ b/board/raspberrypi3/overlay/etc/init.d/S13btuart
@@ -1,12 +1,15 @@
 #!/bin/bash
 
-sys_conf="/etc/bluetooth.conf"
-boot_conf="/boot/bluetooth.conf"
-conf="/data/etc/bluetooth.conf"
+SYS_CONF="/etc/bluetooth.conf"
+BOOT_CONF="/boot/bluetooth.conf"
+CONF="/data/etc/bluetooth.conf"
 
-test -f $conf || test -f $boot_conf || test -f $sys_conf || exit 0
 
-test -n "$os_version" || source /etc/init.d/base
+test -f ${CONF} || test -f ${BOOT_CONF} || test -f ${SYS_CONF} || exit 0
+
+test -d "/proc/device-tree/soc/gpio@7e200000/uart0_pins" || exit 0  # no rpi bluetooth detected
+
+test -n "${OS_VERSION}" || source /etc/init.d/base
 
 function start() {
     if [[ "$(cat /proc/device-tree/aliases/uart0)" = "$(cat /proc/device-tree/aliases/serial1)" ]] ; then
diff --git a/board/raspberrypi3/overlay/usr/libexec/fw-restore-boot-cfg b/board/raspberrypi3/overlay/usr/libexec/fw-restore-boot-cfg
index 628189ebf6..a4cf5afe76 100755
--- a/board/raspberrypi3/overlay/usr/libexec/fw-restore-boot-cfg
+++ b/board/raspberrypi3/overlay/usr/libexec/fw-restore-boot-cfg
@@ -6,5 +6,5 @@ if [ -z "$1" ]; then
 fi
 
 old_boot=$1
-cp $old_boot/config.txt /boot
+cp ${old_boot}/config.txt /boot
 
diff --git a/board/raspberrypi3/postscript.sh b/board/raspberrypi3/postscript.sh
index df98ae0de2..318d9637ca 100755
--- a/board/raspberrypi3/postscript.sh
+++ b/board/raspberrypi3/postscript.sh
@@ -2,16 +2,16 @@
 
 set -e
 
-RPI_FW_DIR=$TARGET/../images/rpi-firmware
+RPI_FW_DIR=${TARGET}/../images/rpi-firmware
 
-cp $BOARD_DIR/config.txt $BOOT_DIR
-cp $BOARD_DIR/cmdline.txt $BOOT_DIR
-cp $BOARD_DIR/fwupdater.gz $BOOT_DIR
-cp $IMG_DIR/zImage $BOOT_DIR/kernel.img
-cp $IMG_DIR/bcm2710-rpi-3-b.dtb $BOOT_DIR
-cp $IMG_DIR/bcm2710-rpi-3-b-plus.dtb $BOOT_DIR
-cp $IMG_DIR/bcm2710-rpi-cm3.dtb $BOOT_DIR
-cp $RPI_FW_DIR/bootcode.bin $BOOT_DIR
-cp $RPI_FW_DIR/start.elf $BOOT_DIR
-cp $RPI_FW_DIR/fixup.dat $BOOT_DIR
+cp ${BOARD_DIR}/config.txt ${BOOT_DIR}
+cp ${BOARD_DIR}/cmdline.txt ${BOOT_DIR}
+cp ${BOARD_DIR}/fwupdater.gz ${BOOT_DIR}
+cp ${IMG_DIR}/zImage ${BOOT_DIR}/kernel.img
+cp ${IMG_DIR}/bcm2710-rpi-3-b.dtb ${BOOT_DIR}
+cp ${IMG_DIR}/bcm2710-rpi-3-b-plus.dtb ${BOOT_DIR}
+cp ${IMG_DIR}/bcm2710-rpi-cm3.dtb ${BOOT_DIR}
+cp ${RPI_FW_DIR}/bootcode.bin ${BOOT_DIR}
+cp ${RPI_FW_DIR}/start.elf ${BOOT_DIR}
+cp ${RPI_FW_DIR}/fixup.dat ${BOOT_DIR}
 
diff --git a/build.sh b/build.sh
index ab9791ee18..d1d3a4866a 100755
--- a/build.sh
+++ b/build.sh
@@ -17,7 +17,7 @@ board=$1
 target=${*:2}
 cd $(dirname $0)
 basedir=$(pwd)
-gzip=$(which pigz || which gzip)
+gzip=$(which pigz 2> /dev/null || which gzip 2> /dev/null)
 
 # extra environment from local file
 test -f $basedir/.build-env && source $basedir/.build-env
@@ -26,14 +26,14 @@ test -f $basedir/.build-env && source $basedir/.build-env
 if [ -n "$THINGOS_SHORT_NAME" ]; then
     osname=$THINGOS_SHORT_NAME
 else
-    osname=$(source $basedir/board/common/overlay/etc/version && echo $os_short_name)
+    osname=$(source $basedir/board/common/overlay/etc/version && echo $OS_SHORT_NAME)
 fi
 
 # OS version
 if [ -n "$THINGOS_VERSION" ]; then
     osversion=$THINGOS_VERSION
 else
-    osversion=$(source $basedir/board/common/overlay/etc/version && echo $os_version)
+    osversion=$(source $basedir/board/common/overlay/etc/version && echo $OS_VERSION)
 fi
 
 # when the special "boards" keyword is used for board, simply list all known boards