docker-mailserver/target/bin/addmailuser

#! /bin/bash

# shellcheck disable=SC2094

# shellcheck source=../scripts/helper-functions.sh
. /usr/local/bin/helper-functions.sh

DATABASE=${DATABASE:-/tmp/docker-mailserver/postfix-accounts.cf}

USER="${1}"
shift
PASSWD="${*}"

function usage  { echo "Usage: addmailuser <user@domain> [<password>]" ; }

[[ -z ${USER} ]] && { usage ; errex "no username specified" ; }
[[ "${USER}" =~ .*\@.* ]] || { usage ; errex "username must include the domain" ; }

# Protect config file with lock to avoid race conditions
touch "${DATABASE}"
(
  flock -e 200

  grep -qi "^$(escape "${USER}")|" "${DATABASE}" 2>/dev/null &&
    errex "User \"${USER}\" already exists"

  if [[ -z ${PASSWD} ]]
  then
    read -r -s -p "Enter Password: " PASSWD
    echo
    [[ -z ${PASSWD} ]] && errex "Password must not be empty"
  fi

  HASH="$(doveadm pw -s SHA512-CRYPT -u "${USER}" -p "${PASSWD}")"
  echo "${USER}|${HASH}" >> "${DATABASE}"
) 200< "${DATABASE}"