OT: Bash script for Mailman export of email addresses

[Nigel Ridley]

Due to circumstances beyond my control I have to move my personal mailing list from Mailman to 
another mailing solution.
I need to export all the email addresses for my subscribers to a csv file and have found a 
one-liner bash script that is supposed to do it but it spits out an error message. The webpage 
for the script is here:
http://literalbarrage.org/blog/2011/11/14/export-mailman-subscriber-address-lists-without-sshshell-access/

The actual script is:
wget -O - --post-data 'adminpw=${admin password}'  http://${listserv domain 
name}/admin.cgi/${list name}/members | egrep "_realname" | sed 
's/^.*value="\([^"]*\)".*value="\([^"]*\)".*$/\1,\2/' | sed 's/%40/@/' > maillist.csv

The error I get is:
bash: http://${box220.bluehost.com/mailman/admin/**********/}/admin.cgi/${*********}/members: bad 
substitution

I have written to the owner of the above website but had no replies as of yet and time is running 
out.

Can someone who is familiar with bash spot any obvious reasons for the error?

Any help would be greatly appreciated.

TIA,

Nigel