#!/bin/sh

# This runs the given COMMAND on a sliding window of pairs of arguments.
# For example, "pairwise diff f1 f2 f3 f4 f5" becomes:
#     diff f1 f2
#     diff f2 f3
#     diff f3 f4
#     diff f4 f5

: ${1?"Usage: $0 COMMAND ARG1 ARG2 ARG3 ... ARGN"}

COMMAND=$1
shift

fn1=''
for fn in "$@"; do
	if [ -z "${fn1}" ]; then
		fn1=${fn}
		continue
	fi
	"${COMMAND}" "${fn1}" "${fn}"
	fn1=${fn}
done