tree-hash-combine

#!/bin/bash -e

file1=$1
file2=$2
outfile=$(echo "hash.$file1.$file2" | sed 's,part,,g' | sed 's,\.hash,,g' | sed -E 's,\.+,.,g')

# only run if both args are specified
if [ -n "$file1" -a -n "$file2" ]; then
  tempfile=$(mktemp);
  cat "$file1" "$file2" \
    | openssl dgst -sha256 -binary \
    > $tempfile

  mv $tempfile $file1
  rm $file2
fi