wizard

wizard n.  1. A person who knows how a complex piece of
   software or hardware works (that is, who {grok}s it); esp.
   someone who can find and fix bugs quickly in an emergency.  Someone
   is a {hacker} if he or she has general hacking ability, but is a
   wizard with respect to something only if he or she has specific
   detailed knowledge of that thing.  A good hacker could become a
   wizard for something given the time to study it.  2. A person who
   is permitted to do things forbidden to ordinary people; one who has
   {wheel} privileges on a system.  3. A UNIX expert, esp. a UNIX
   systems programmer.  This usage is well enough established that
   `UNIX Wizard' is a recognized job title at some corporations and to
   most headhunters.  See {guru}, {lord high fixer}.  See also
   {deep magic}, {heavy wizardry}, {incantation}, {magic},
   {mutter}, {rain dance}, {voodoo programming}, {wave a
   dead chicken}.