Mergs PDF files using GhostScript

merge_pdfs.sh

#!/bin/sh

if [ $# -eq 0 ]; then
    echo 1>&2 Usage: $0 output.pdf source.pdf [source2.pdf ...]
    exit 127
fi

for arg in $*
do
    let "i += 1"
    if [ $i -eq 1 ];
    then
        output=$arg
    else
        pdfs="$pdfs $arg"
    fi
done

gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=$output $pdfs