docker-mailserver/target/bin/fetchmailrc_split

#! /bin/bash

# Description: This script will split the content of /etc/fetchmailrc into
#              smaller fetchmailrc files per server [poll] entries. Each
#              separate fetchmailrc file is stored in /etc/fetchmailrc.d
#
#              The mail purpose for this is to work around what is known
#              as the Fetchmail IMAP idle issue.
#

FETCHMAILRC="/etc/fetchmailrc"
FETCHMAILRCD="/etc/fetchmailrc.d"
DEFAULT_FILE="${FETCHMAILRCD}/defaults"

if [[ ! -r "${FETCHMAILRC}" ]]
then
  echo "Error: File ${FETCHMAILRC} not found"
  exit 1
fi

if [[ ! -d ${FETCHMAILRCD} ]]
then
  if ! mkdir "${FETCHMAILRCD}"
  then
    echo "Error: Unable to create folder ${FETCHMAILRCD}"
    exit 1
  fi
fi

COUNTER=0
SERVER=0
while read -r LINE
do
  if [[ ${LINE} =~ poll ]]
  then
    # If we read "poll" then we reached a new server definition
    # We need to create a new file with fetchmail defaults from
    # /etc/fetcmailrc
    COUNTER=$((COUNTER+1))
    SERVER=1
    cat "${DEFAULT_FILE}" > "${FETCHMAILRCD}/fetchmail-${COUNTER}.rc"
    echo "${LINE}" >> "${FETCHMAILRCD}/fetchmail-${COUNTER}.rc"
  elif [[ ${SERVER} -eq 0 ]]
  then
    # We have not yet found "poll". Let's assume we are still reading
    # the default settings from /etc/fetchmailrc file
    echo "${LINE}" >> "${DEFAULT_FILE}"
  else
    # Just the server settings that need to be added to the specific rc.d file
    echo "${LINE}" >> "${FETCHMAILRCD}/fetchmail-${COUNTER}.rc"
  fi
# delete commented lines before parsing
done < <(sed '/^[[:space:]]*#/d' "${FETCHMAILRC}")

rm "${DEFAULT_FILE}"