Synopsis:
   $open(<file> R|W)

Technical:
   This functions allows the client to open an arbitrary file for reading or
   writing.  Write mode appends to the file.  The function returns a file
   descriptor for the open file; the file descriptor is an integer.  Tilde-
   expansion is permitted.

Practical:
   The $open() function is the doorway to external file access from within
   the client (aside from EXECing a process).  Assuming the file has the
   appropriate permissions, it allows you to open the file for read or
   write access (but not both).  Write access only appends to the file, so
   you'll need to use $unlink() or $rename() if you want to start fresh.

Returns:
   file descriptor, or nothing if error

Options:
   R   open file for reading
   W   open file for writing

Examples:
   $open(~/.ircrc W)                 open your .ircrc for writing
   $open(~/.irclog R)                open your logfile for reading
   $open(/etc/passwd W)              will probably fail

See Also:
   close(6); randread(6); read(6); rename(6); unlink(6);
   write(6); writeb(6)