EzWinScore Renaming Shell Script

This is a script to rename the output files from EzWinScore for emailing. I don't like spaces in the names, and the finals files aren't named properly.

#!/bin/sh

BASE=`ls -1 | perl -e 'while (<>) { print $1 and exit if ($_ =~ "(.{4}_[0-9]{4}_[0-9]{2}_[0-9]{2})") }'`

if [ -z ${BASE} ] ; then
  echo "*"
  echo "* Couldn't find any files that matched the regex!  Aborting..."
  echo "*"
  exit
else
  if [ ! -e "Pistol All divisions.txt" ] ; then
    echo "*"
    echo "*  Eeek!  File 'Pistol All divisions.txt' doesn't exist!  Aborting..."
    echo "*"
    exit
  fi

  if [ ! -e "Pistol Finals  All divisions.txt" ] ; then
    echo "*"
    echo "*  Eeek!  File 'Pistol Finals  All divisions.txt' doesn't exist!  Aborting..."
    echo "*"
    exit
  fi

  mv "Pistol All divisions.txt" ${BASE}_Pistol_All_Divisions.txt
  mv "Pistol Finals  All divisions.txt" ${BASE}_Pistol_Finals_All_Divisions.txt

  if [ -e "${BASE}_Single Stack.txt" ] ; then
    mv "${BASE}_Single Stack.txt" "${BASE}_Single_Stack.txt"
  fi
fi