Computer:~ Me$ sudo '/Applications/Gnucash.app/Contents/Resources/bin/gnc-fq-dump' yahoo_europe RMG.L
Finance::Quote fields Gnucash uses:
    symbol: RMG.L                <=== required
      date: 08/24/2015           <=== required
  currency: GBP                  <=== required
      last: 4.6758               <=\
       nav:                      <=== one of these
     price: 4.6758               <=/
  timezone:                      <=== optional