while (<IN>) {
   # print if /$pattern/; # normal "grep"
   print unless /$pattern/; # grep -v
}

##</code><code>##

print $_ unless $_ =~ /$pattern/;

##</code><code>##

perl -e 'print "How sweet does a rose smell? "; chomp ($n = <STDIN>); $rose = "smells sweet to degree $n"; *other_name = *rose; print "$other_name\n"'