docker-mailserver/target/bin/listmailuser

#! /bin/bash

# ? This is done to ignore the message "Make sure not to read and write
# ? the same file in the same pipeline", which is a result of ${DATABASE}
# ? being used below. (This disables the message file-wide.)
# shellcheck disable=SC2094

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

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

[[ -f ${DATABASE} ]] || errex "Error: No postfix-virtual.cf file"
[[ -s ${DATABASE} ]] || errex "Error: Empty postfix-virtual.cf - no aliases have been added"

# Lock database even though we are only reading
(
  flock -e 200
  ( grep -v "^\s*$\|^\s*\#" "${DATABASE}" || true ) | awk -F '|' '{ print $1; }'
) 200< "${DATABASE}"