Improved encrypted paper backup guide

how-to-create-encrypted-paper-backup/secure-erase.sh

@@ -0,0 +1,71 @@
+#! /bin/bash
+
+iterations=3
+
+positional=()
+while [[ $# -gt 0 ]]; do
+  argument="$1"
+  case $argument in
+    -h|--help)
+    printf "%s\n" \
+    "Usage: secure-erase.sh [options]" \
+    "" \
+    "Options:" \
+    "  --iterations   overwrite n times (defauls to 3)" \
+    "  --zero         overwrite with zeros to hide secure erase" \
+    "  -h, --help     display help for command"
+    exit 0
+    ;;
+    --iterations)
+    iterations=$2
+    shift
+    shift
+    ;;
+    --zero)
+    zero=true
+    shift
+    ;;
+    *)
+    positional+=("$1")
+    shift
+    ;;
+  esac
+done
+
+set -- "${positional[@]}"
+
+red=$(tput setaf 1)
+normal=$(tput sgr0)
+
+dev="/dev/sda1"
+
+tput reset
+
+waitForUsbThumbDrive () {
+  if [ ! -e $dev ]; then
+    printf "Insert USB flash drive and press enter"
+    read -r confirmation
+    waitForUsbThumbDrive
+  fi
+}
+
+waitForUsbThumbDrive
+
+printf "$red%s$normal\n" "Secure erase USB flash drive? (y or n)? "
+
+read -r answer
+if [ "$answer" = "y" ]; then
+  array=($(seq 1 1 $iterations))
+  for iteration in ${array[@]}; do
+    printf "%s\n" "Erasing… (iteration $iteration of $iterations)"
+    sudo dd bs=1M if=/dev/urandom of=$dev
+  done
+  if [ "$zero" = true ]; then
+    printf "%s\n" "Writing zeros…"
+    sudo dd bs=1M if=/dev/zero of=$dev
+  fi
+else
+  exit 0
+fi
+
+printf "%s\n" "Done"