[OT] iMac backups

[Greg Keogh]

Folks, I have to take a snapshot of about 9GB of files on my El Capitan
iMac. On Windows I would plugin a stick or portable and run robocopy with
the /XD and /XF switches to exclude junk, but I'm not sure what the
equivalent is on OSX. Does anyone have a handy technique for doing this
sort of thing? Perhaps there are mysterious Unix commands I can use from
the Terminal prompt -- *Greg K*