Add backup script.

bin/backup.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+set -o nounset
+set -o errexit
+
+DEFAULT=`echo /media/${USER}/[bB]ackup/${USER}/`
+DEST="${1:-${DEFAULT}}"
+
+function verify_dest {
+  arr=($1)
+  items=${#arr[@]}
+  if [ $items -ne 1 ] ; then
+    echo "Bad count of backup destinations." > /dev/stderr
+    exit 1
+  fi
+  dir="$1"
+  end=$((${#dir}-1))
+  last="${dir:$end:1}"
+  if [ "$last" != "/" ] ; then
+    echo -n "Destination $dir does not end in a /, " > /dev/stderr
+    echo "this is probably not what you want!" > /dev/stderr
+    echo "Press a key to continue, or CTRL-C to cancel." > /dev/stderr
+    read
+  fi
+}
+
+verify_dest "$DEST"
+
+rsync -Hax --delete-before --exclude-from="$HOME/.rsync_ignore" "${HOME}/" "$DEST"