#!/bin/bash
# find-splitpara.sh
#  Finds split paragraphs in a text file,
#+ and tags the line numbers.


ARGCOUNT=1       # Expect one arg.
OFF=0            # Flag states.
ON=1
E_WRONGARGS=85

file="$1"        # Target filename.
lineno=1         # Line number. Start at 1.
Flag=$OFF        # Blank line flag.

if [ $# -ne "$ARGCOUNT" ]
then
  echo "Usage: `basename $0` FILENAME"
  exit $E_WRONGARGS
fi  

file_read ()     # Scan file for pattern, then print line.
{
while read line
do

  if [[ "$line" =~ ^[a-z] && $Flag -eq $ON ]]
     then  # Line begins with lowercase character, following blank line.
     echo -n "$lineno::   "
     echo "$line"
  fi


  if [[ "$line" =~ ^$ ]]
     then       #  If blank line,
     Flag=$ON   #+ set flag.
  else
     Flag=$OFF
  fi

  ((lineno++))

done
} < $file  # Redirect file into function's stdin.

file_read


exit $?


# ----------------------------------------------------------------
This is line one of an example paragraph, bla, bla, bla.
This is line two, and line three should follow on next line, but

there is a blank line separating the two parts of the paragraph.
# ----------------------------------------------------------------

Running this script on a file containing the above paragraph
yields:

4::   there is a blank line separating the two parts of the paragraph.


There will be additional output for all the other split paragraphs
in the target file.