>To: Jim Plank <plank@cs.utk.edu>
>Subject: Use of $ to reference last line of input stream
>
>According to the Oreilly book on SED/AWK (p.61) the $ can be used to
>reference the last line of the input stream ... i.e. sed -n $p should
>print only the last line ... yet this doesn't seem to work on either
>SUNOS or SOLARIS ... have you seen it work anywhere? 

From the lecture notes:

   You can specify an address by its line number, or as a range of line
   numbers, separated by a comma. Thus, you specify lines 6 through 10 as
   ``6,10''. The last line can be specified by the dollar sign.

UNIX> sed '2,$d' usopen                        # delete all but the first line
     1  Ernie Els -- -4     -4    0 
UNIX>

To do your example, you need to have the '$p' in single quotes.  
Otherwise the shell tries to substitute the binding for the 'p' 
environment variable.

UNIX> sed -n $p usopen
p: Undefined variable.
UNIX> sed -n '$p' usopen
    20  Lee Westwood -- +6     -4    10
UNIX>