#!/bin/sh

fn=/tmp/$USER.$$

if [ $# -eq 0 ]; then
  cat > $fn
elif [ $# -eq 1 ]; then
  if [ ! -f "$1" ]; then
    echo "Cannot access file $1" >&2
    exit 1
  else
    cat "$1" > $fn
  fi
else
  echo "usage: mail_strip [ file ]" >&2
  exit 1
fi

set "a "`head -1 $fn | grep '^From [^ ]'`

if [ $# -eq 1 ]; then
  echo "Not a mail file" >&2
  rm -f $fn
  exit 1
fi

nm=`grep '^From [^ ]' $fn | wc -l`


while [ $nm -gt 1 ]; do
  em=`sed -n '1s/From \([^ 	]*\).*/\1/p' $fn`
  echo "writing to $em" >&2
  ed - $fn << EOF
  1s/^//
  /^From [^ ]/,\$d
  W $em
  q
EOF
  ed - $fn << EOF
  1s/^//
  1,/^From [^ ]/-1d
  w
  q
EOF
nm=`echo $nm - 1 | bc`
done

em=`sed -n '1s/From \([^      ]*\).*/\1/p' $fn`
echo "writing to $em" >&2
cat $fn >> $em
rm -f $fn