Simple script to write to sdcard on OSX

write-to-sdcard

#!/bin/bash

# (c) 2016 Kamil Trzciński <ayufan@ayufan.eu>
# Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php

stderr() {
	echo "$@" 1>&2
}

if [[ $# -ne 1 ]] && [[ $# -ne 2 ]]; then
	stderr "Usage: $0 <file> [disk]"
	exit 1
fi

FILE="$1"

set -eo pipefail

if [[ ! -e "$FILE" ]]; then
	stderr "File $FILE doesn't exist"
	exit 1
fi

is_external() {
	diskutil info $1 | grep -q "\(USB\|Secure Digital\)"
}

devices() {
	diskutil list | grep "^/dev/" | awk '{print $1}'
}

uncompress_file() {
	case "$(basename "$FILE")" in
		*.gz)
			stderr "Uncompressing $FILE to $SELECTED_DISK..."
			gunzip -c
			;;

		*.xz)
			stderr "Uncompressing $FILE to $SELECTED_DISK..."
			unxz -c
			;;

		*)
			stderr "Copying $FILE to $SELECTED_DISK..."
			cat
			;;
	esac
}

SELECTED_DISK=""

for device in $(devices); do
	# Just in case!
	if [[ "$device" == "/dev/disk0" ]]; then
		continue
	fi

	if ! is_external "$device"; then
		continue
	fi

	if [[ -n "$2" ]]; then
		if [[ "$device" == "$2" ]]; then
			SELECTED_DISK="$device"
		fi
		continue
	fi

	if [[ "$SELECTED_DISK" != "" ]]; then
		stderr "Multiple disks found: $device"
		exit 1
	fi

	SELECTED_DISK="$device"
done

if [[ -z "$SELECTED_DISK" ]]; then
	stderr "No disk found."
	exit 1
fi

stderr "Using: $device..."

if ! diskutil unmountDisk "$SELECTED_DISK"; then
	stderr "Failed to unmount $SELECTED_DISK"
	exit 1
fi

if pv "$FILE" | uncompress_file | sudo dd of="$SELECTED_DISK" bs=1m; then
	stderr "Succeeded."
else
	stderr "Failed."
	exit 1
fi