replace string within file and the filename

I have a string test.cgi@action=<action-name>

<action-name> can be any string

I would like to replace the above string with <action-name>.html

Can any one please let me know how I can proceed with t开发者_开发知识库his using a Perl script?

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$string =~ s/test\.cgi@action=(.*?)/$1.html/g;