#! /bin/sh
set -euf

# require flock from util-linux
if test "${FLOCK-}" != "$state_file"; then
  exec env FLOCK="$state_file" flock "$state_file" "$0" "$@"
fi

from="$_prefix"
to="$1"; shift
msg="$*"
date=$(date)

# TODO tell now, if already joined
printf '%s %s <%s> %s\n' "$to" "$from" "$date" "$msg" >> "$state_file"

echo 'Consider it noted.' # that's what lambdabot says...