diff-cmd.sh

#! /bin/bash

opt=()
while test $# -gt 0 -a "${1:0:1}" = -; do
    opt=("${opt[@]}" "$1")
    shift
done

if test $# -lt 3; then 
    echo Usage: $0 [diff options] command [command options] file-a file-b
    exit 1
fi

cmd=${@:1:$(($#-2))}
shift $(($#-2))

exec diff ${opt[@]} --label "$1" --label "$2" <(${cmd[@]} "$1") <(${cmd[@]} "$2")