#!/bin/sh
if [ $# -eq 0 ] || [ "$1" = "-h" ]; then
cat <<EOF
Usage: ${0##*/} STRING FILES
Prepend STRING to FILES. STRING may not contain pipes ('|').
EOF
exit
fi
VAR="$1"
shift
sed -ni '1{s|^|'$VAR'\n|;h};1!H;${x;p}' "$@"