BeagleBone format_sd Script

format_sd.sh

#!/bin/bash

# Format an SD card for use in a TI development kit to boot u-boot and Linux.
# The layout is a small 32 MB FAT partition and a larger (remainder of device)
# ext4 partition.  The FAT partition starts at 1 MB and the ext4 partition
# immediately follows.

# Stop execution on any error condition
set -e

# Echo all executed statements, useful for debugging
#set -x

echo_usage() {
	echo "Usage: $0 [DEVICE]"
	echo "Format an SD card DEVICE for use in TI dev kits"
	echo
	echo "DEVICE should be a block device like /dev/mmcblk0 or /dev/sdc."
	echo "The device needs to be unmounted for this script to function."
}

# Exit showing a human readable string plus error number in red
die() {
	local _num=${1}
	local _name=${2}
	if [ ! ${_num} ]; then
		_num="255"
	fi
	if [ ! "${_name}" ]; then
		_name="unspecified"
	fi
	if [ ${_num} -ne 0 ]; then
		echo -e "\e[1;31mError: ${_name}, exiting with status ${_num}\e[0m" >&2
	fi
	exit ${_num}
}

#########################
# Execution Starts Here #
#########################

# Ensure host has all the needed commands installed
awk -V > /dev/null || die 1 "could not find awk executable on your PATH"
fdisk -h > /dev/null || die 1 "could not find fdisk executable on your PATH"
sfdisk -h > /dev/null || die 1 "could not find sfdisk executable on your PATH"
which mkfs.vfat > /dev/null || die 1 "could not find mkfs.vfat executable on your PATH"
which mkfs.ext4 > /dev/null || die 1 "could not find mkfs.ext4 executable on your PATH"

# Determine the version of sfdisk as versions from util-linux 2.26 and newer
# do not support the old style parameters or command line switches and need a
# new type.
NEWSFDISK=0
_SFDISKVER=`sfdisk -v | cut -d' ' -f 4`
_SFDISKVERMAJOR=`echo ${_SFDISKVER} | cut -d'.' -f 1`
_SFDISKVERMINOR=`echo ${_SFDISKVER} | cut -d'.' -f 2`
if [[ ${_SFDISKVERMAJOR} -gt 2 || ( ${_SFDISKVERMAJOR} -eq 2 && ${_SFDISKVERMINOR} -gt 25) ]]; then
	NEWSFDISK=1
fi

# Determine the version of mkfs.ext4 as v1.43 and newer need some defaults
# disabled due to u-boot not supporting them
NEWEXT4DEFAULTS=0
_MKFSEXT4VER=`mkfs.ext4 -V 2>&1 | head -n 1 | cut -d' ' -f 2`
_MKFSEXT4VERMAJOR=`echo ${_MKFSEXT4VER} | cut -d'.' -f 1`
_MKFSEXT4VERMINOR=`echo ${_MKFSEXT4VER} | cut -d'.' -f 2`
if [[ ${_MKFSEXT4VERMAJOR} -gt 1 || ( ${_MKFSEXT4VERMAJOR} -eq 1 && ${_MKFSEXT4VERMINOR} -gt 42 ) ]]; then
	NEWEXT4DEFAULTS=1
fi

if [ ${#} -ne 1 ]; then
	echo_usage
	die 1 "no DEVICE specified"
fi

DEVICE=$1
DEVICE_IS_MOUNTED=`grep ${DEVICE} /proc/self/mounts | wc -l`
if [ ${DEVICE_IS_MOUNTED} -ne 0 ]; then
	die 1 "device is currently mounted"
fi

if [ ! -b "$DEVICE" ] ; then
	die 1 "device is not a block device"
fi

SIZE=`fdisk -l $DEVICE | grep Disk | awk '{print $5}'`

echo
read -p "${DEVICE} is ${SIZE} bytes, continue to format it? [N,y]: " ANSWER

case ${ANSWER} in
	y|Y|yes|Yes)
		;;
	*)
		die 0 "user terminated"
		;;
esac

# Blow away the master boot record and partition the disk
dd if=/dev/zero of=${DEVICE} bs=1024 count=1
if [ ${NEWSFDISK} -eq 1 ]; then
{
echo "label: dos"
echo "start=1MiB size=32MiB type=0x0C bootable"
echo "start=33MiB"
} | sfdisk ${DEVICE}
else
{
echo 1,32,0x0C,*
echo 33,,,-
} | sfdisk ${DEVICE}
fi

# USB connected cards will have their partitions show up like /dev/sdc1 while
# real MMC devices will have their partitions show up like /dev/mmcblk0p1
`echo "${DEVICE}" | grep "mmc"` && DEVICE="${DEVICE}p"

# Format the partitions, ensure the metadata_csum and 64bit options for ext4 are
# disabled as u-boot does not support them yet some versions of mkfs.ext4 will
# use them in the default set of features.
mkfs.vfat -n "BOOT" ${DEVICE}1
if [ ${NEWEXT4DEFAULTS} -eq 1 ]; then
	mkfs.ext4 -L "rootfs" -O ^metadata_csum,^64bit ${DEVICE}2
else
	mkfs.ext4 -L "rootfs" ${DEVICE}2
fi