. binds less strong than ~= does. Using double quotes or parentheses makes your code work. Change

                        && ($DOCROOT.$uri !~ /\/$/)) {
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                        && ("$DOCROOT$uri" !~ /\/$/)) {
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or, even better, construct a variable $local_path from $DOCROOT and $uri. Note that your webserver will allow access to directories outside of $DOCROOT if $uri contains for example ../../.