Fetching mail from pop3 via bash. Accept any pop3 command, augmented with a "last" command.

fetchmail.sh

#!/bin/bash
# Wed Jun 16 16:04:19 EDT 2004
# NAME: p1
# Copyright 2004, Chris F.A. Johnson
# Released under the terms of the GNU General Public License
# Modified by Alexandre Kaspar <xion.luhnis(at)gmail(dot)com>
# Using https://gist.github.com/jjarmoc/1571540

CR=$'\r'  ## carriage return; for removal of

SERV=mysmtp.com
USER=myusername
PASS=mypassword

## connect to POP3 server on local machine, port 110
exec 3<>/dev/tcp/$SERV/110

## get response from server
read ok line <&3

## check that it succeeded
[ "${ok%$CR}" != "+OK" ] && exit 5

## send user name, get response and check that it succeeded
echo user "$USER" >&3
read ok line <&3
[ "${ok%$CR}" != "+OK" ] && exit 5

## send password, get response and check that it succeeded
echo pass "$PASS" >&3
read ok line <&3
[ "${ok%$CR}" != "+OK" ] && exit 5

## get number of messages
echo stat >&3
read ok num x <&3

## display number of messages
echo $num messages

## commands
# @see https://gist.github.com/jjarmoc/1571540
alias qpd='perl -MMIME::QuotedPrint -pe '\''$_=MIME::QuotedPrint::decode($_);'\'''
shopt -s expand_aliases
if [[ $# -ge 1 ]]; then
  # special "last" command
  command="$@"
  if [ "$command" = "last" ]; then
    command="retr $num"
  fi

  # do the command request now
  echo "$command" >&3
  
  # check result
  read ok line <&3
  [ "${ok%$CR}" != "+OK" ] && echo "$ok $line" && exit 5

  while read line <&3;
  do
    # break condition
    [ "$line" = ".$CR" ] && break;

    # display content line
    echo $line | qpd
  done
fi

## close connection
echo quit >&3