b> - name of primary group of local user
  <li><b>%h</b> - client's DNS name
  <li><b>%m</b> - FTP command (e.g. RETR, STOR, etc)
  <li><b>%r</b> - full FTP command
  <li><b>%U</b> - original username sent by client
  <li><b>%u</b> - name of local user
  <li><b>%v</b> - name of server handling session
  <li><b>%w</b> - RNFR path ("whence" a rename comes, <i>i.e.</i> the source path)
</ul>
The <i>value</i> parameter may be also be &quot;-&quot;, which indicates that
the current value of the environment varia