Shell Programming and Scripting

#!/bin/ksh

# The fact that we set IFS only on new line is that in this question
# space and tabs are not considered as delimiters, only new lines
IFS='
'

FINAL_RESULT=""
RESULT=""

function concatenate
{
    VARIABLE1=$1
    VARIABLE2=$2
    
        
    CURRENT_LINE_NUMBER_IN_VARIABLE1=1
    CURRENT_LINE_NUMBER_IN_VARIABLE2=1
    
    for ITERATOR1 in $VARIABLE1
    do
        CURRENT_LINE_NUMBER_IN_VARIABLE2=1
        for ITERATOR2 in $VARIABLE2
        do
            if (( CURRENT_LINE_NUMBER_IN_VARIABLE2 < 
                 CURRENT_LINE_NUMBER_IN_VARIABLE1 ))
            then
                (( CURRENT_LINE_NUMBER_IN_VARIABLE2 = 
                      CURRENT_LINE_NUMBER_IN_VARIABLE2 + 1 ))
                
            else
                FINAL_RESULT="$FINAL_RESULT\n$ITERATOR1$ITERATOR2"
                (( CURRENT_LINE_NUMBER_IN_VARIABLE2 = 
                      CURRENT_LINE_NUMBER_IN_VARIABLE2 + 1 ))
                break;
            fi
        done
    
    (( CURRENT_LINE_NUMBER_IN_VARIABLE1 = 
            CURRENT_LINE_NUMBER_IN_VARIABLE1 + 1 ))
    done
    
(( TOTAL_LENGTH_MINUS_FIRST_NEW_LINE = ${#FINAL_RESULT} - 2 ))
FINAL_RESULT=${FINAL_RESULT:2:$TOTAL_LENGTH_MINUS_FIRST_NEW_LINE}
}

# In this example we suppose VARIABLE1 and VARIABLE2 are those lines
# that have to be concatenated, each line by its corresponding in
# another variable
VARIABLE1="var1 first line
var1 second line
var1 third line
var1 forth line
var1 fifth line"

VARIABLE2="var2 first line
var2 second line
var2 third line
var2 forth line
var2 fifth line"



concatenate "$VARIABLE1" "$VARIABLE2"

print $FINAL_RESULT