Shell Programming and Scripting

ISA^M00^M          ^M00^M          ^M14^M006929681900   ^M01^M095449419      ^M061130^M2240^MU^M00401^M000003791^M0^MP^M>~GS^MPO^M006929681900^M095449419^M20061130^M2240^M41^MX^M004010~ST^M850^M000000059~BEG^M00^MNE^M11302346F2600^M^M20061130~REF^MIA^M0028910^MTANKO COMPANY~FOB^MPP^MDE^M00300DO~ITD^M^M^M^M^M^M^M^M^M^M^M^M 02%  60  DAYS~DTM^M010^M20061214~TD5^M^M^M^M^MAUTHORIZED CARRIER~

Now all I want is :
1) To identify my delimiter character at 4th position(which is ^M[single character] for this file and it could be varying for other files) 
2) Change the delimiter character whatever it is to *(asterisk)
3) To identify my newline character at 105 position(which is a tilde(~) in this file and it could be varying for other files)
4) Break into new line when ever there is a newline character which cud be ~ or any thing else.
5)Finally changed file should look like below :
ISA*00*          *00*          *14*006929681900   *01*095449419      *061130*2240*U*00401*000003791*0*P*>
GS*PO*006929681900*095449419*20061130*2240*41*X*004010
ST*850*000000059
BEG*00*NE*11302346F2600**20061130
REF*IA*0028910*TANKO COMPANY
FOB*PP*DE*00300DO
ITD************ 02%  60  DAYS
DTM*010*20061214
TD5*****AUTHORIZED CARRIER
6)Also when the script is run on already formatted file like above it should not disturb the file since it is already in perfect shape.

sed -e 's/^M/*/g' -e 's/~/\n/g' file

Char4=`head -1 input_file | cut -c4`
Char106=`head -1 input_file | cut -c106`
sed -e "s/$Char4/*/g" -e "s/$Char106/\n/g" input_file

#!/usr/bin/ksh
set -x
#======================================================#
# char_count = Number of characters in the first line of file                  
# sed is used to trim the leading blank spaces in the char_count variable     
#======================================================#
char_count=$(head -1 $1 | wc -c)
char_count=`echo "${char_count}" | sed 's/^ *//'`
# If char_count <> 106 (which means whole file content is in 1 line then format
if [[ $char_count -ne 106 ]]
then
#======================================================#
# Finds the delimiter character from 4th position in file and replaces the
# delimiter with '*' using 'tr'. Stores into temp1.txt
#======================================================#
field_delimiter=$(cut -c 4 $1)
tr "$field_delimiter" '*' < $1 > temp1.txt
#======================================================#
#Finds the newline character at 106th position
# Replaces all newline characters in temp1.txt to '\n' and stores as temp2.txt
#======================================================#
newline_char=$(cut -c 106 $1)
tr "$newline_char" '\n' < temp1.txt > temp2.txt
#======================================================#
# Deletes all the blank lines from the file                                    
#======================================================#
sed '/^$/d' temp2.txt > $1
#======================================================#
# Deletes temp1.txt and temp2.txt files                                        
#======================================================#
rm -f temp1.txt temp2.txt
#======================================================#
fi