sd.sh -- spool and sniff stdin stream to dispatch depending on contents

sd.sh

#!/bin/bash
#
# sd.sh -- spool and sniff stdin stream to dispatch depending on contents
#
# Dependencies: basename, bash, cat, head, mktemp, stat, tail, tr.
#

set -e

header=$(mktemp -t $(basename $0)-XXXXXX)
trap "rm -f $header" EXIT

head -c 262 > $header

size=$(stat --printf="%s" $header)

if [ $size -eq 262 -a "$(tail --bytes=5 $header | tr -d '\0')" = "ustar" ]; then
  echo "tarball: yes" 1>&2
else
  echo "tarball: no" 1>&2
fi

exec cat $header -