#!/usr/bin/perl -w

###############  The Range Operators and the $. Special Variable  ##############
open(F, "$ARGV[0]") or die "Cannot open $ARGV[0]!\n";

while (<F>)
{
    print if /#/../#/;   #####  Won't be what you want in all likelihood!
}

open(F, "$ARGV[0]") or die "Cannot open $ARGV[0]!\n";
print "*" x 50, "\n";   ####  Divider line between output of 1st and 2nd loops!

while (<F>)
{
    print if /#/.../#/;   #####  This ** is ** what you want in all likelihood!
}
############################  Program Output  #################################

$ dot.pl x    #####  Program invocation.

Contents of input file (x)
--------------------------

this is junk.
this is more junk.
#   abc  #
123
456
#   xyz  #
hi there
#  testing, testing! 
inside
outside
USA
#end of test
more garbage.

Screen Output
-------------

#   abc  #
#   xyz  #
#  testing, testing! 
#end of test
**************************************************
#   abc  
123
456
#   xyz  
#  testing, testing! 
inside
outside
USA
#end of test

########  The moral of this story?  If you're using /regexp/ then use ...
########  and not ..