if [[ -z "$1" ]]; then
  echo No input file
  exit
fi

input=$1
middle=`mktemp -t pdf_2on1`.pdf

if [[ -z "$2" ]]; then
  name="${input%.*}"
  ext="${input##*.}"
  output=${name}_2on1.$ext
else
  output=$2
fi

pdfnup --frame true "$input" "$input" --outfile "$middle" 2>/dev/null
pdfjam --landscape --trim '1mm 1mm 1mm 1mm' --clip true "$middle" --outfile "$output" 2>/dev/null
rm "$middle"