BeOS‘ query engine works just as well from the command line as it does from Tracker. In fact, it can do some things Tracker can’t especially when combined with other shell tools.
The easiest way to build a query is to construct it normally in the GUI query tool, then use the drop-down to switch to „Formula“ mode. Select the entire formula and copy it to the clipboard.
Now, in a Terminal window, type query "", then backspace so your cursor is between the quote marks, paste from the clipboard, and hit Enter. Now you can do things like build your queries into scripts, or run the query results through other shell tools to create lists (e.g. create a text dump of all your Person files who live in California).