1) “R.J. Decker” (ABC) or “Line of Fire” (NBC), both 8 p.m. Most scripted shows haven’t started their seasons yet, but these two began early and have reruns here. For “Decker” (10 p.m. Tuesdays), it’s the second episode, with a missing man and a dangerous stranger. For “Fire” (10 p.m. Mondays), it’s the pilot film, ending with a stark game-changer; shown here is the second generation in a family of federal agents.
2) “20/20” (ABC) or “Dateline” (NBC) season-openers, 9-11 p.m. Both news magazines — well, mostly true-crime shows — will again be head-to-head all season. Starting next week, ABC will have “Celebrity Wheel of Fortune” at 8. NBC will wait until Oct. 23 for “Happy’s Place” and “Newlyweds.”
3) “Sing America 250,” 9-10:30 p.m., PBS. The intentions are good, the music is sometimes splendid, but the TV production (especially in the first half) is quite inept. This offers optimistic choral and orchestral music, combining several Minnesota groups.
4) “S.W.A,T.: Exiles,” 10 p.m., Starz. After eight CBS seasons, the show returns, this time with Hondo (Shemar Moore) assembling a team of mostly rejects. That wraps a busy week for streamers and premium networks, including “Brothers” on Apple and both a “Different World” reboot and a “Willy Wonka” reality show on Netflix.
5) ALSO: “Sheriff Country” and “Boston Blue” have reruns at 9 and 10 p.m., preceded by the season’s final “Big Brother: Unlocked.” And at 9 ET, Turner Classic Movies has “The Great Dictator” (1940), Charlie Chaplin’s first not-silent movie, linking comedy with satire of Hitler. It’s preceded at 8 by a documentary showing parallels in the two men’s lives.