regex match with interpolated pattern

drock has asked for the wisdom of the Perl Monks concerning the following question:

I have tried to match a pattern stored in a variable like so 08/14/04.


my $dm=08/14/04;
open F, file
while (<F>) {
if ( $_ =~ /$dm/ ) {

blah
blah 
blah
}

if ( $_ =~ m/^\$dm/ ) 

if ( $_ =~ m/[$dm]/ )
[download]

I cannot get it to pull on certain dates from a file. My file looks like 08/14/04 timestampe exxxxx

20040819 Edit by broquaint: Changed title from 'reg exp'