Make resin.io SD image burning a little less painful on a Mac

resin.img.burner.sh

#!/bin/bash
echo "------------------------------------------------------------------------"
if [[ "$#" -ne 2 ]]; then
    echo "IMG Burner -- Built for macbook pros w/ the SD card slot on the right."
    echo " - Insert a blank SD card"
    echo " - run with two args - img file and destination disk (typically disk2, disk3, etc.  NEVER disk1 or sda1)"
    echo " - run $ mount  to see what disks are available"
    echo " - Example: $ ./resin.img.burn.sh path/to/resin.img disk2"
    exit
fi
SRC=$1
DEVICE=$2
DEST="/dev/${DEVICE}s1"
DDOF="/dev/r${DEVICE}"


# make sure our source image exists
if [[ -f "$SRC" ]]; then
    IFS=' ' read -ra BYTES <<< `wc -c $SRC`
    # figure out the destination file size
    echo " + Found $SRC -- $BYTES bytes"
else
    echo " ! Could not find $SRC"
    exit 1
fi

# make sure we have a device @ the expected location
if mount | grep $DEST > /dev/null;  then
    echo " + Found an SD Card @ $DEST (hope you don't have anything important on it)"
else
    echo " ! Cannot find an SD card @ $DEST -- insert one and verify $DEVICE is the right disk"
    exit 1
fi

# start a clock
START=$(date +%s)

echo " + Unmounting $DEST (requires your password)"
sudo diskutil unmount $DEST

echo " + Burning $SRC to $DEST"
echo " + Writing $BYTES bytes total..."
echo "   (CTRL+t for progress...)"

# do the actual work
sudo dd bs=1m if=$SRC of=$DDOF
afplay /System/Library/Sounds/Ping.aiff
sudo diskutil unmountDisk $DDOF

# stop the clock
END=$(date +%s)
DIFF=$(echo "$END - $START" | bc)
echo " + Finished in $DIFF seconds!"
echo " + The SD card is unmounted, so yank it out and do another."
echo "------------------------------------------------------------------------"
echo ""