diff --git a/flash-it.sh b/flash-it.sh
index cf95837..417f108 100755
--- a/flash-it.sh
+++ b/flash-it.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 VERSION="0.3.3"
 BRANCH=master
@@ -28,202 +28,225 @@ MOUNT_BOOT=./boot
 
 # Parse arguments
 # https://stackoverflow.com/questions/192249/how-do-i-parse-command-line-arguments-in-bash
-POSITIONAL=()
-while [[ $# -gt 0 ]]
-do
-key="$1"
+unset POSITIONAL
+while [ "$#" -gt 0 ]; do
+	case "$1" in
+		-b|--branch)
+			BRANCH="$2"
+			shift 2
+			;;
+		-h|--help)
+			printf '%s\n'  "Sailfish OS flashing script for Pine64 devices
+This script will download the latest Sailfish OS image for the Pine
+Phone, Pine Phone dev kit, or Pine Tab. It requires that you have a
+micro SD card inserted into the computer.
 
-case $key in
-    -b|--branch)
-        BRANCH="$2"
-        shift
-        shift
-        ;;
-    -h|--help)
-        echo "Sailfish OS flashing script for Pine64 devices"
-        echo ""
-        printf '%s\n' \
-               "This script will download the latest Sailfish OS image for the Pine" \
-               "Phone, Pine Phone dev kit, or Pine Tab. It requires that you have a" \
-               "micro SD card inserted into the computer." \
-               "" \
-               "usage: flash-it.sh [-b BRANCH]" \
-               "" \
-               "Options:" \
-               "" \
-               "	-c, --custom		Install from custom dir. Just put you rootfs.tar.bz2" \
-               "				and u-boot-sunxi-with-spl.bin into dir and system will "\
-               "				istalled from it" \
-               "	-b, --branch BRANCH	Download images from a specific Git branch." \
-               "	-h, --help		Print this help and exit." \
-               "" \
-               "This command requires: parted, sudo, wget, tar, unzip, lsblk," \
-               "mkfs.ext4." \
-               ""\
-               "Some distros do not have parted on the PATH. If necessary, add" \
-               "parted to the PATH before running the script."
+usage: flash-it.sh [-b BRANCH]
 
-        exit 0
-        shift
-        ;;
-	-c|--custom)
-		CUSTOM="$2"
-		shift
-		shift
-		;;
-    *) # unknown argument
-        POSITIONAL+=("$1") # save it in an array for later
-        shift # past argument
-        ;;
-esac
+Options:
+
+-c, --custom Install from custom dir. Just put you rootfs.tar.bz2
+             and u-boot-sunxi-with-spl.bin into dir and system will
+             istalled from it
+-b, --branch BRANCH	Download images from a specific Git branch.
+-h, --help   Print this help and exit.
+
+This command requires: parted; sudo, doas or su; wget or curl; tar, unzip, lsblk,
+and mkfs.ext4.
+
+Some distros do not have parted on the PATH. If necessary, add
+parted to the PATH before running the script."
+			exit 0
+			;;
+		-c|--custom)
+			CUSTOM="$2"
+			shift 2
+			;;
+		*) # unknown argument
+			POSITIONAL="$POSITIONAL:$1" # save it in a list for later
+			shift # past argument
+			;;
+	esac
 done
-set -- "${POSITIONAL[@]}" # restore positional parameters
+# Retrieve saved arguments
+IFS=: set -- ${POSITIONAL#:}
 
 # Helper functions
-# Error out if the given command is not found on the PATH.
-function check_dependency {
-    dependency=$1
-    command -v $dependency >/dev/null 2>&1 || {
-        echo >&2 "${dependency} not found. Please make sure it is installed and on your PATH."; exit 1;
-    }
+
+# Run as root
+as_root() {
+	command -V sudo >/dev/null 2>&1 && {
+		sudo "$@"
+		return "$?"
+	}
+	command -V doas >/dev/null 2>&1 && {
+		doas "$@"
+		return "$?"
+	}
+	command -V su >/dev/null 2>&1 && {
+		su -c "$*"
+		return "$?"
+	}
 }
 
-# Add sbin to the PATH to check for commands available to sudo
-function check_sudo_dependency {
-    dependency=$1
-    local PATH=$PATH:/sbin:/usr/sbin:/usr/local/sbin
-    check_dependency $dependency
+# Print message to stderr and exit
+die() {
+	printf '%s\n' "$*" >&2
+	exit "${status:-2}"
+}
+# Error out if the given command is not found on the PATH.
+check_dependency() {
+    command -V "$1" >/dev/null 2>&1 ||
+        status=1 die "$1 not found. Please make sure it is installed and in your PATH."
+}
+
+# Check if one or more of depends are present
+check_alternative_dependencies() {
+	IFS=', ' all="$*"
+	unset found
+	while [ "$1" ]; do
+		command -V "$1" >/dev/null 2>&1 && {
+			found=y
+			break
+		}
+		shift
+	done
+
+	[ "$found" ] || die "None of '$all found'. Please make sure one of them is installed and in your PATH."
 }
 
 # Determine if wget supports the --show-progress option (introduced in
 # 1.16). If so, make use of that instead of spewing out redirects and
 # loads of info into the terminal.
-function wget_cmd {
-    wget --show-progress > /dev/null 2>&1
-    status=$?
+set_wget_cmd() {
+	if command -V wget >/dev/null 2>&1; then
 
-    # Exit code 2 means command parsing error (i.e. option does not
-    # exist).
-    if [ "$status" == "2" ]; then
-        echo "wget -O"
-    else
-        echo "wget -q --show-progress -O"
-    fi
+		if wget --help 2>&1 | grep -q 'show-progress'; then
+			WGET="wget -q --show-progress -O"
+		else
+			WGET="wget -O"
+		fi
+
+	else
+		WGET="curl -Lo"
+	fi
 }
 
+# Add sbin to the PATH to make sure all commands are found
+export PATH="$PATH:/sbin:/usr/sbin:/usr/local/sbin"
 # Check dependencies
-check_dependency "sudo"
-check_dependency "wget"
-check_dependency "tar"
-check_dependency "unzip"
-check_dependency "lsblk"
-check_sudo_dependency "parted"
-check_sudo_dependency "mkfs.ext4"
-check_sudo_dependency "losetup"
+check_alternative_dependencies sudo doas su
+check_alternative_dependencies wget curl
+check_dependency tar
+check_dependency unzip
+check_dependency lsblk
+check_dependency parted
+check_dependency mkfs.ext4
+check_dependency losetup
 
 # If use custom dir check it
-if [ "$CUSTOM" != "" ]; then
-	if ! [ -d "$CUSTOM" ]; then
-		echo -e "\e[1m\e[97m!!! Directory ${CUSTOM} not exist !!!\e[0m"
-		exit 2;
+if [ "$CUSTOM" ]; then
+	if [ ! -d "$CUSTOM" ]; then
+		die "!!! Directory $CUSTOM not exist !!!"
 	fi
 
-	if ! [ -f "$CUSTOM/rootfs.tar.bz2" ]; then
-		echo -e "\e[1m\e[97m!!! rootfs ${CUSTOM}/rootfs.tar.bz2 not found !!!\e[0m"
-		exit 2;
+	if [ ! -f "$CUSTOM/rootfs.tar.bz2" ]; then
+		die "!!! rootfs $CUSTOM/rootfs.tar.bz2 not found !!!"
 	fi
 
-	if ! [ -f "$CUSTOM/u-boot-sunxi-with-spl.bin" ]; then
-		echo -e "\e[1m\e[97m!!! uboot image ${CUSTOM}/u-boot-sunxi-with-spl.bin not found !!!\e[0m"
-		exit 2;
+	if [ ! -f "$CUSTOM/u-boot-sunxi-with-spl.bin" ]; then
+		die "!!! uboot image $CUSTOM/u-boot-sunxi-with-spl.bin not found !!!"
 	fi
 
 	if ! [ -f "$CUSTOM/boot.scr" ]; then
-		echo -e "\e[1m\e[97m!!! uboot config ${CUSTOM}/boot.scr not found !!!\e[0m"
-		exit 2;
+		die "!!! uboot config $CUSTOM/boot.scr not found !!!"
 	fi
 else
-# Different branch for some reason?
-if [ "${BRANCH}" != "master" ]; then
-    echo -e "\e[1m\e[97m!!! Will flash image from ${BRANCH} branch !!!\e[0m"
-fi
+	# Different branch for some reason?
+	if [ "$BRANCH" != master ]; then
+		printf '%s\n' "!!! Will flash image from $BRANCH branch !!!"
+	fi
 
-# Header
-echo -e "\e[1m\e[91mSailfish OS Pine64 device flasher V$VERSION\e[0m"
-echo "======================================"
-echo ""
+	# Header
+	printf '%s\n' "Sailfish OS Pine64 device flasher V$VERSION
+======================================
+"
 
-# Image selection
-echo -e "\e[1mWhich image do you want to flash?\e[0m"
-select OPTION in "PinePhone 1.0 (Development) device" "PinePhone 1.1 (Brave Heart) or 1.2 (Community Editions) device" "PineTab device" "PineTab Dev device" "Dont Be Evil devkit"; do
-    case $OPTION in
-        "PinePhone 1.0 (Development) device" ) ROOTFS_JOB=$ROOTFS_PINEPHONE_1_0_JOB; ROOTFS_DIR=$ROOTFS_PINEPHONE_1_0_DIR; UBOOT_DEV_DIR=$UBOOT_PINEPHONE_1_0_DIR; break;;
-        "PinePhone 1.1 (Brave Heart) or 1.2 (Community Editions) device" ) ROOTFS_JOB=$ROOTFS_PINEPHONE_1_1_JOB; ROOTFS_DIR=$ROOTFS_PINEPHONE_1_1_DIR; UBOOT_DEV_DIR=$UBOOT_PINEPHONE_1_1_DIR; break;;
-        "PineTab device" ) ROOTFS_JOB=$ROOTFS_PINETAB_JOB; ROOTFS_DIR=$ROOTFS_PINETAB_DIR; UBOOT_DEV_DIR=$UBOOT_PINETAB_DIR; break;;
-        "PineTab Dev device" ) ROOTFS_JOB=$ROOTFS_PINETABDEV_JOB; ROOTFS_DIR=$ROOTFS_PINETABDEV_DIR; UBOOT_DEV_DIR=$UBOOT_PINETABDEV_DIR; break;;
-        "Dont Be Evil devkit" ) ROOTFS_JOB=$ROOTFS_DEVKIT_JOB; ROOTFS_DIR=$ROOTFS_DEVKIT_DIR; UBOOT_DEV_DIR=$UBOOT_DEVKIT_DIR; break;;
-    esac
-done
+	# Image selection
+	printf '%s\n' "Which image do you want to flash?"
 
-# Downloading images
-echo -e "\e[1mDownloading images...\e[0m"
-WGET=$(wget_cmd)
-UBOOT_DOWNLOAD="https://gitlab.com/sailfishos-porters-ci/dont_be_evil-ci/-/jobs/artifacts/$BRANCH/download?job=$UBOOT_JOB"
-$WGET "${UBOOT_JOB}.zip" "${UBOOT_DOWNLOAD}" || {
-	echo >&2 "UBoot image download failed. Aborting."
-	exit 2
-}
+	: $(( i = 0 ))
+	for opt in "PinePhone 1.0 (Development) device" "PinePhone 1.1 (Brave Heart) or 1.2 (Community Editions) device" "PineTab device" "PineTab Dev device" "Dont Be Evil devkit"; do
+		: $(( i += 1 ))
+		printf '%s\n' "$i) $opt"
+	done
+	printf '%s' "#? "
+	read -r OPTION
 
-UBOOT_DOWNLOAD2="https://gitlab.com/pine64-org/crust-meta/-/jobs/artifacts/master/raw/u-boot-sunxi-with-spl-pinephone.bin?job=build"
-$WGET "u-boot-sunxi-with-spl-pinephone.bin" "${UBOOT_DOWNLOAD2}" || {
-	echo >&2 "UBoot image download failed. Aborting."
-	exit 2
-}
+	case "$OPTION" in
+		1) ROOTFS_JOB=$ROOTFS_PINEPHONE_1_0_JOB; ROOTFS_DIR=$ROOTFS_PINEPHONE_1_0_DIR; UBOOT_DEV_DIR=$UBOOT_PINEPHONE_1_0_DIR;;
+		2) ROOTFS_JOB=$ROOTFS_PINEPHONE_1_1_JOB; ROOTFS_DIR=$ROOTFS_PINEPHONE_1_1_DIR; UBOOT_DEV_DIR=$UBOOT_PINEPHONE_1_1_DIR;;
+		3) ROOTFS_JOB=$ROOTFS_PINETAB_JOB; ROOTFS_DIR=$ROOTFS_PINETAB_DIR; UBOOT_DEV_DIR=$UBOOT_PINETAB_DIR;;
+		4) ROOTFS_JOB=$ROOTFS_PINETABDEV_JOB; ROOTFS_DIR=$ROOTFS_PINETABDEV_DIR; UBOOT_DEV_DIR=$UBOOT_PINETABDEV_DIR;;
+		5) ROOTFS_JOB=$ROOTFS_DEVKIT_JOB; ROOTFS_DIR=$ROOTFS_DEVKIT_DIR; UBOOT_DEV_DIR=$UBOOT_DEVKIT_DIR;;
+		*) die "Invalid selection";;
+	esac
 
+	# Downloading images
+	printf '%s\n' "Downloading images..."
+	set_wget_cmd
+	UBOOT_DOWNLOAD="https://gitlab.com/sailfishos-porters-ci/dont_be_evil-ci/-/jobs/artifacts/$BRANCH/download?job=$UBOOT_JOB"
+	$WGET "$UBOOT_JOB.zip" "$UBOOT_DOWNLOAD" || {
+		die "UBoot image download failed. Aborting."
+	}
 
-ROOTFS_DOWNLOAD="https://gitlab.com/sailfishos-porters-ci/dont_be_evil-ci/-/jobs/artifacts/$BRANCH/download?job=$ROOTFS_JOB"
-$WGET "${ROOTFS_JOB}.zip" "${ROOTFS_DOWNLOAD}" || {
-	echo >&2 "Root filesystem image download failed. Aborting."
-	exit 2
-}
+	UBOOT2_JOB=u-boot-sunxi-with-spl-pinephone.bin
+	UBOOT_DOWNLOAD2="https://gitlab.com/pine64-org/crust-meta/-/jobs/artifacts/master/raw/u-boot-sunxi-with-spl-pinephone.bin?job=build"
+	$WGET "$UBOOT2_JOB" "$UBOOT_DOWNLOAD2" || {
+		die "UBoot image download failed. Aborting."
+	}
+
+	ROOTFS_DOWNLOAD="https://gitlab.com/sailfishos-porters-ci/dont_be_evil-ci/-/jobs/artifacts/$BRANCH/download?job=$ROOTFS_JOB"
+	$WGET "$ROOTFS_JOB.zip" "$ROOTFS_DOWNLOAD" || {
+		die "Root filesystem image download failed. Aborting."
+	}
 fi
 
 # Select flash target
-echo -e "\e[1mWhich SD card do you want to flash?\e[0m"
+printf '%s\n' "Which SD card do you want to flash?"
 lsblk
-echo "raw"
-read -p "Device node (/dev/sdX): " DEVICE_NODE
-echo "Flashing image to: $DEVICE_NODE"
-echo "WARNING: All data will be erased! You have been warned!"
-echo "Some commands require root permissions, you might be asked to enter your sudo password."
+printf '%s\n%s\n' "raw" "Device node (/dev/sdX): "
+read -r DEVICE_NODE
+printf '%s\n' "Flashing image to: $DEVICE_NODE
+WARNING: All data will be erased! You have been warned!
+Some commands require root permissions, you might be asked to enter your password."
 
 #create loop file for raw.img
-if [ $DEVICE_NODE == "raw" ]; then
-	sudo dd if=/dev/zero of=sdcard.img bs=1 count=0 seek=4G
-	DEVICE_NODE="./sdcard.img"
+if [ "$DEVICE_NODE" = raw ]; then
+	as_root dd if=/dev/zero of=sdcard.img bs=1 count=0 seek=4G
+	DEVICE_NODE=./sdcard.img
 fi
 
 # Creating EXT4 file system
-echo -e "\e[1mCreating EXT4 file system...\e[0m"
-for PARTITION in $(ls ${DEVICE_NODE}*)
-do
+printf '%s\n' "Creating EXT4 file system..."
+for PARTITION in "$DEVICE_NODE"*; do
     echo "Unmounting $PARTITION"
-    sudo umount $PARTITION
+    as_root umount "$PARTITION"
 done
-sudo parted $DEVICE_NODE mklabel msdos --script
-sudo parted $DEVICE_NODE mkpart primary ext4 1MB 250MB --script
-sudo parted $DEVICE_NODE mkpart primary ext4 250MB 100% --script
+as_root parted "$DEVICE_NODE" mklabel msdos --script
+as_root parted "$DEVICE_NODE" mkpart primary ext4 1MB 250MB --script
+as_root parted "$DEVICE_NODE" mkpart primary ext4 250MB 100% --script
 
-if [ $DEVICE_NODE == "./sdcard.img" ]; then
-	echo "Prepare loop file"
-	sudo losetup -D
-	sudo losetup -Pf sdcard.img
-	LOOP_NODE=`ls /dev/loop?p1 | cut -c10-10`
+if [ "$DEVICE_NODE" = ./sdcard.img ]; then
+	printf '%s\n' "Prepare loop file"
+	as_root losetup -D
+	as_root losetup -Pf sdcard.img
+	LOOP_NODE="$(echo /dev/loop?p1 | cut -c10-10)"
 	DEVICE_NODE="/dev/loop$LOOP_NODE"
 fi
 
 # use p1, p2 extentions instead of 1, 2 when using sd drives
-if [ $(echo $DEVICE_NODE | grep mmcblk || echo $DEVICE_NODE | grep loop) ]; then
+if echo "$DEVICE_NODE" | grep -q -E 'mmcblk|loop'; then
 	BOOTPART="${DEVICE_NODE}p1"
 	DATAPART="${DEVICE_NODE}p2"
 else
@@ -231,67 +254,63 @@ else
 	DATAPART="${DEVICE_NODE}2"
 fi
 
-sudo mkfs.ext4 -F -L boot $BOOTPART # 1st partition = boot
-sudo mkfs.ext4 -F -L data $DATAPART # 2nd partition = data
+as_root mkfs.ext4 -F -L boot "$BOOTPART" # 1st partition = boot
+as_root mkfs.ext4 -F -L data "$DATAPART" # 2nd partition = data
 
 # Flashing u-boot
-echo -e "\e[1mFlashing U-boot...\e[0m"
-if [ "$CUSTOM" != "" ]; then
-sudo dd if="${CUSTOM}/u-boot-sunxi-with-spl.bin" of="$DEVICE_NODE" bs=8k seek=1
+printf '%s\n' "Flashing U-boot..."
+if [ "$CUSTOM" ]; then
+	as_root dd if="$CUSTOM/u-boot-sunxi-with-spl.bin" of="$DEVICE_NODE" bs=8k seek=1
 else
-unzip "${UBOOT_JOB}.zip"
-sudo dd if="./u-boot-sunxi-with-spl-pinephone.bin" of="$DEVICE_NODE" bs=8k seek=1
+	unzip "$UBOOT_JOB.zip"
+	as_root dd if="./u-boot-sunxi-with-spl-pinephone.bin" of="$DEVICE_NODE" bs=8k seek=1
 fi
 sync
 
 # Flashing rootFS
-echo -e "\e[1mFlashing rootFS...\e[0m"
+printf '%s\n' "Flashing rootFS..."
 mkdir "$MOUNT_DATA"
-if [ "$CUSTOM" != "" ]; then
-    TEMP="${CUSTOM}/rootfs.tar.bz2"
+if [ "$CUSTOM" ]; then
+    TEMP="$CUSTOM/rootfs.tar.bz2"
 else
-    unzip "${ROOTFS_JOB}.zip"
-    TEMP=`ls $ROOTFS_DIR/*/*.tar.bz2`
+    unzip "$ROOTFS_JOB.zip"
+	TEMP="$(echo $ROOTFS_DIR/*/*.tar.bz2)"
     echo "$TEMP"
 fi
-sudo mount $DATAPART "$MOUNT_DATA" # Mount data partition
-sudo tar -xpf "$TEMP" -C "$MOUNT_DATA"
+as_root mount "$DATAPART" "$MOUNT_DATA" # Mount data partition
+as_root tar -xpf "$TEMP" -C "$MOUNT_DATA"
 sync
 
 # Copying kernel to boot partition
-echo -e "\e[1mCopying kernel to boot partition...\e[0m"
+printf '%s\n' "Copying kernel to boot partition..."
 mkdir "$MOUNT_BOOT"
-sudo mount $BOOTPART "$MOUNT_BOOT" # Mount boot partition
-echo "Boot partition mount: $MOUNT_BOOT"
-sudo sh -c "cp -r $MOUNT_DATA/boot/* $MOUNT_BOOT"
+as_root mount "$BOOTPART" "$MOUNT_BOOT" # Mount boot partition
+printf '%s\n' "Boot partition mount: $MOUNT_BOOT"
+as_root chmod a+rx "$MOUNT_DATA/boot"
+as_root cp -r "$MOUNT_DATA/boot"/* "$MOUNT_BOOT"
 
-echo `ls $MOUNT_BOOT`
-if [ "$CUSTOM" != "" ]; then
-    sudo sh -c "cp '${CUSTOM}/boot.scr' '$MOUNT_BOOT/boot.scr'"
+echo "$MOUNT_BOOT"
+if [ "$CUSTOM" ]; then
+    as_root cp "$CUSTOM/boot.scr" "$MOUNT_BOOT/boot.scr"
 else
-    sudo sh -c "cp './u-boot-bootloader/$UBOOT_DEV_DIR/boot.scr' '$MOUNT_BOOT/boot.scr'"
+    as_root cp "./u-boot-bootloader/$UBOOT_DEV_DIR/boot.scr" "$MOUNT_BOOT/boot.scr"
 fi
 sync
 
 # Clean up files
-echo -e "\e[1mCleaning up!\e[0m"
-for PARTITION in $(ls ${DEVICE_NODE}*)
-do
+printf '%s\n' "Cleaning up!"
+for PARTITION in "$DEVICE_NODE"*; do
     echo "Unmounting $PARTITION"
-    sudo umount $PARTITION
+    as_root umount "$PARTITION"
 done
 
-sudo losetup -D
+as_root losetup -D
 
-if [ "$CUSTOM" == "" ]; then
-    rm "${UBOOT_JOB}.zip"
-    rm -r "$UBOOT_DIR"
-    rm "${ROOTFS_JOB}.zip"
-    rm -r "$ROOTFS_DIR"
+if [ -z "$CUSTOM" ]; then
+    rm -r "$UBOOT_JOB.zip" "$UBOOT2_JOB" "$UBOOT_DIR" "$ROOTFS_JOB.zip" "$ROOTFS_DIR"
 fi
-sudo rm -rf "$MOUNT_DATA"
-sudo rm -rf "$MOUNT_BOOT"
+as_root rm -rf "$MOUNT_DATA" "$MOUNT_BOOT"
 
 # Done :)
-echo -e "\e[1mFlashing $DEVICE_NODE OK!\e[0m"
-echo "You may now remove the SD card and insert it in your Pine64 device!"
+printf '%s\n' "Flashing $DEVICE_NODE OK!
+You may now remove the SD card and insert it in your Pine64 device!"