mk_save_file.sh

#!/bin/bash
declare -a options="$(getopt -o f:,s:,t: --long input-file:size:,type: -- "$@")"
eval set --"$options"
while [ $# -gt 0 ]; do
  case "$1" in
  -f|--input-file)
     rwbranch=$2;
     shift 2; ;;
   -s|--size)
     size=$2;
     shift 2; ;;
   -t|--type) #Not Yet implemented
     size=$2;
     shift 2; ;;
   *)
     shift; ;; #This should never happen
  esac
done
TMPFILE=$(mktemp -p /tmp)
if [ -z "$rwbranch" ]; then
  echo "create"
  dialog --backtitle "rw image sandbox" --title "Specify name and path of new the file" --fselect `pwd` 8 60 2> $TMPFILE
  rwbranch=`cat $TMPFILE`
  rm $TMPFILE
fi
if [ -z "$size" ]; then

  dialog --title "Create new rw image" --inputbox "Specify size (in megabytes)" 0 40 100 2> $TMPFILE
  size=`cat $TMPFILE`
  rm $TMPFILE
fi
if [ -n "$rwbranch" ]; then
    if [ -f "$rwbranch" ]; then
        echo "$rwbranch already exist - exiting."
        exit
    else
        # get the size
        if [ -n "$size" ]; then
          dialog --title "Create new rw image" --inputbox "Specify size (in megabytes)" 0 40 100 2> $TMPFILE
          size=`cat $TMPFILE`
          rm $TMPFILE
        fi
        if [ -n "$size" ]; then
            if dd if=/dev/zero of="$rwbranch" bs=1 count=0 seek="$size"M; then
                if ! mke2fs -F "$rwbranch"; then
                    echo "I fail to make an ext2 filesystem at $rwbranch, exiting."
                    exit
                fi
            else
                echo "I fail to create a ${size}M file at $rwbranch, exiting."
                exit
            fi
        else
            echo "You didn't specify the size or your press cancel. Exiting."
            exit
        fi
    fi
else
    echo "You didn't specify any file or you pressed cancel. Exiting."
    exit
fi