#! /usr/bin/perl -w

#   scr07D.pl
#   How to search a text string among incoming lines?  
#   Please use "Regular Expression" which has a whole set of text matching grammar.
#   Regular Expression is placed in two regular slashes /.../.



open (IN, "Ref.txt");

while( <IN> )       ## Get One-line each time from an external file "Ref.txt".
{   

                                        ## If incoming text line has my favorite nuts,
                                        ## then print out only that text line. 
                                        ## <=  Here comes a Regular Expression.
   if ( /chestnut/ || /walnut/ ) {    
       print "Found a line of text, which has my favorite nuts : $_";     
   }
}

close (IN);