Enlarge filesystem to use the entire device storage space after dd image to device

enlarge_image.sh

#!/bin/bash

# This script is doing exactly the opposite of what shrink_image.sh is,
# which will resize the filesystem to use maximum storage space of
# the given device
#
# This is typically done after dd a shrinked image file to this given device
#

DEVICE_FILE=$1

function perr_and_exit()
{
  echo "$1" >&2
  exit 1
}

function is_device_file()
{
  if [[ $(stat -c "%t" $1) == "8" ]]; then
    return 0
  else
    return 1
  fi
}

function usage()
{
  cat << EOM
Usage: $0 device_file

This script is designed to enlarge filesystem to use all unallocated spaces. This is typically done after dd a shrinked image file to a device. Using it improperly may cause unrecoverable damage. Use at your own risk!

Example: $0 /dev/sda

EOM
}

if [[ ! $(whoami) =~ "root" ]]; then
  echo "This script requires root privilege!"
  exit 1
fi

if ! is_device_file $DEVICE_FILE; then
  echo "ERROR: $DEVICE_FILE is not an device file!"
  exit 2
fi

if mount | egrep -q "^$DEVICE_FILE"; then
  perr_and_exit "ERROR: Device file $DEVICE_FILE should be umounted first"
fi

if [[ $(ls -1 ${DEVICE_FILE}?? | wc -l) != "1" ]]; then
  perr_and_exit "ERROR: Only support image containing one partition."
fi

DEVICE_PARTITION_1=$(ls -1 ${DEVICE_FILE}??)

if ! parted $DEVICE_PARTITION_1 p | tail -n 2 | head -n 1 | grep ext4 &>/dev/null; then
  perr_and_exit "ERROR: Only ext4 filesystem is supported"
fi

# Enlarge partition first
parted $DEVICE_FILE rm 1 mkpart primary ext4 0% 100% || perr_and_exit "ERROR: Failed to run parted on device $DEVICE_FILE"

# Check disk status
e2fsck -f $DEVICE_PARTITION_1 || perr_and_exit "ERROR: Failed to run e2fsck on partition $DEVICE_PATITION_1"

# Enlarge file system
resize2fs $DEVICE_PARTITION_1