perl -wle '$_="|<br />|"; s{<br />}{\par}ig; print'
Unrecognized escape \p passed through at -e line 1.
|par|

##</code><code>##

perl5.10.0 -wle '$_="!<br />!"; s{<br />}{\\par}ig; print'|hexdump -C
00000000  21 5c 70 61 72 21 0a                              |!\par!.|
00000007