Many restaurants host an evening for friends and family before a formal opening as a dress rehearsal for the real thing. Such was the case on Sept. 16 at the Brooklyn bistro 21 Greenpoint, formerly known as River Styx. It was reopening, under the same owners, with a new menu and a new look.

Most friends-and-family nights are intimate affairs. Not this one. There were camera crews on the sidewalk and a line of people stretching from Greenpoint Avenue nearly to the East River.

The restaurant’s co-owner, Homer Murray, had let it be known that there would be a special guest bartender on duty that night: his father, the actor and urban folk hero Bill Murray. But at 7:15 the 65-year-old star of “Ghostbusters,” “Groundhog Day” and “Lost in Translation” had yet to arrive for a shift scheduled to begin at 7.

From inside 21 Greenpoint, the younger Mr. Murray and the restaurant’s bar director, Sean Patrick McClure, a veteran of Le Bernardin and Dirty French, kept an eye on the growing crowd. Asked to describe his father’s bartending skills, Mr. Murray said: “He just kind of pours Slovenia Vodka into people’s glasses when they look thirsty. He’s about efficiency. Turn-and-burn.”