A simple Spotlight search can be performed by clicking the Spotlight icon in the top-right corner of your Mac's screen while a more advanced search (based on kind, date, name, contents, device make, album, artist, bit rate, city, codec, EXIF data, language, height, width, etc.) can be performed by using the Spotlight search box in the top-right corner of a Finder window.
These simple or advanced searches can also be performed on the command line by using the mdfind utility.
To perform a simple search, enter a command like this:
To perform a search in a specific directory, enter a command like this to search only the "Documents" folder in your "Home" folder:
mdfind -onlyin ~/Documents geekology
To see a count of matches instead of the actual matches, add the "-count" argument to the command:
mdfind -count -onlyin ~/Documents geekology
To see a live (continually updated) list (or count) of results, use a command like this:
mdfind -live -onlyin ~/Documents geekology
To search for results based on a specific metatag (e.g. "kMDItemTitle"), use a command like this:
mdfind -onlyin ~/Documents "kMDItemTitle == '*geekology*'"
For more information on mdfind's arguments, see it's man page:
To see a specific file's metatags, use the mdls utility:
…and to see all possible metatags use this command: