"I tried this script but I got an error message, "EOH" seems to be undefined here....?"

The second EOH needs to be on a line by itself, with no leading or trailing whitespace. See "perlop: Quote-Like Operators: here-document" for details.

[For future reference, please post error messages, in their entirety, between <code>...</code> tags, so that we can see a verbatim copy: a synoptic, prosaic rendering of the message is typically not that helpful.]