#!/bin/sh size=1024 fstype=ext4 label=casper-rw print_usage() { echo 'Usage: CreatePersistentImg.sh [ -s size ] [ -t fstype ] [ -l LABEL ]' echo ' OPTION: (optional)' echo ' -s size in MB, default is 1024' echo ' -t filesystem type, default is ext4 ext2/ext3/ext4/xfs are supported now' echo ' -l label, default is casper-rw' echo '' } while [ -n "$1" ]; do if [ "$1" = "-s" ]; then shift size=$1 elif [ "$1" = "-t" ]; then shift fstype=$1 elif [ "$1" = "-l" ]; then shift label=$1 elif [ "$1" = "-h" ] || [ "$1" = "--help" ]; then print_usage exit 0 else print_usage exit 1 fi shift done # check label if [ -z "$label" ]; then echo "The label can NOT be empty." exit 1 fi # check size if echo $size | grep -q "^[0-9][0-9]*$"; then if [ $size -le 1 ]; then echo "Invalid size $size" exit 1 fi else echo "Invalid size $size" exit 1 fi # check file system type # nodiscard must be set for ext2/3/4 # -K must be set for xfs if echo $fstype | grep -q '^ext[234]$'; then fsopt='-E nodiscard' elif [ "$fstype" = "xfs" ]; then fsopt='-K' else echo "unsupported file system $fstype" exit 1 fi # 00->ff avoid sparse file dd if=/dev/zero bs=1M count=$size | tr '\000' '\377' > persistence.dat sync freeloop=$(losetup -f) losetup $freeloop persistence.dat mkfs -t $fstype $fsopt -L $label $freeloop sync losetup -d $freeloop