/a/b/c/dir1|50
/a/b/c/dir2|50
/a/b/c/dir3|50

while read file_rec
do
        dir_name=`echo "${file_rec}" | cut -d "|" -f 1`
        purge_days=`echo "${file_rec}" | cut -d "|" -f 2`

You dont need to call external commands to split strings. Either use parameter expansion:

Code:

dir_name=${file_rec%|*}
purge_days=${file_rec#*|}

Or use multiple variables in your read command:

Code:

IFS='|' read dir_name purge_days

  if [ -d $dir_name ]

Quote your variable references:

Code:

  if [ -d "$dir_name" ]

  then
    echo "#### The purge days for the directory ${dir_name} is ${purge_days} ####" >> $log
    # To list files with the format YY-MM-DD
	  find ${dir_name} -type f -name \"*[1-2][09][0-9][0-9]-[01][0-9]-[0-3][0-9]*\" -mtime +${purge_days} -exec ls -ltr {} \\; >> $log

Don't escape the quotes or the backslash:

Code:

find "$dir_name" -type f -name "*[1-2][09][0-9][0-9]-[01][0-9]-[0-3][0-9]*" \
                                -mtime +"$purge_days" -exec ls -ltr {} \; >> $log

The -t and -r options to ls will not do anything as you are giving ls a single filename

  else
    echo "*** The directory $dir_name does not exists ***" >> $log
  fi
  dir_name=""
  purge_days=""
  done < dirs.conf