Tonight’s Live at the Rock free concert series pays homage to the Man in Black with the Johnny Cash tribute group, The Partly Jack Band, at Saturday night’s 8 p.m. free concert at Tortoise Rock Casino. “Live at the Rock” presents a new tribute band on the outdoor stage every Saturday night. The Partly Jack Band covers Johnny Cash classics from his six decades in music, including “Ring of Fire,” “Walk the Line,” “Hurt,” and more. And don’t miss coming tributes to Ozzy Osbourne, then we close out August with a tribute to The Who.