To interpolate a variable within a string, enclose it in " " quotes. If you want to interpret the string literally, you can use ' ' quotes. See perldata for more information.

To concatenate strings, use the . operator as discussed in perlop.

Your code features several lines of the form:

$telnet->print('helo '$v_server);

Note that you attempt to pass a literal string ('helo') and concatenate it (with $v_server), but you didn't use the concatenation operator, hence the syntax error.

I believe you were looking for either of the following:

$telnet->print('helo '.$v_server); # Concatenation method
$telnet->print("helo $v_server");  # Interpolation method
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Lastly, your suspicions about $telnet->print('helo $v_server'); were correct -- it does not interpolate, and consequently prints the literal string: helo $v_server.