#!/usr/bin/perl
while(<>) {
        chomp;
        s/^\s+//;
        s/\s+$//;
        next if /^$/; #Next if empty...
        #do something with the text copied to this loop...
        
        #just to do something as an example...
        print "$_ \n";
}

##</code><code>##

#1st Example
a  #input (a)
a  #output

#2nd Example
a  #input (a newline b pasted to the loop)
ba #input and output
   #press enter
b  #output

#3rd Example
a  #input (a newline b pasted to the loop)
ba #input and output
c  #input (c)
bc #output and output

##</code><code>##

a #input
a #output

a #input (a newline b pasted to the loop)
b #continuing
a #output
b #without pressing enter again