Sigh. Trivial syntax errors like this should be picked up and fixed in no time flat, and with strictures they are. Add use strict; use warnings; to your code and you will see:

syntax error at noname.pl line 4, near "tr/[/url][/["
Missing right curly or square bracket at noname.pl line 4, at end of l
+ine
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reported. Code that you obtain from elsewhere ought to have strictures added and then any issues flaged ought to be looked at. Note though that there is valid code around that will throw up warnings and errors - often because the code is using techniques that have been deemed unsafe in some sense. Edit with care!