Ten pubs, more or less, clustered around the Square and the streets running off it. You can walk the lot.
Around the Square
The Galtee Inn on the Square is the one to try first if you want a pint and something to eat in the same sitting. It is a traditional pub with a proper kitchen behind it, and its reputation locally is built on generous, unfussy food at fair prices rather than on anything clever.
The Punters Rest is also on the Square, at number 11, and leans sporting. Matches on the screens, a darts board, a crowd in for whatever is on. Live music on Sunday evenings. Of the town centre pubs it is the one most reliably busy.
Morrissey's is the third of the central ones and the plainest. A bar, and a good one.
Live music
Irwins is the live music pub in Cahir, and has a reasonable claim to being one of the better small venues in south Tipperary. Bands and DJs at weekends, not a fiddle in the corner. Go for a night out, not a quiet session. Have a look at the building while you are there.
The Shamrock Lounge also puts on music at weekends.
For traditional music specifically, Cahir Comhaltas is the branch of the national traditional music organisation covering the town, and their page is a better guide to what is on than any list here can be. Sessions move, and they move for the same reasons everything else does in a town this size.
The rest of them
Cahir also has The Abbey Tavern, The Lady Gregory Bar, The Bell, Brendan's Lounge and the Farmhouse Bar. Local bars, used by locals. Nobody is going to drive across the county for any of them and nobody expects you to.
Food, coffee and the rest
Several of the pubs do bar food, and the Galtee Inn is the most consistent of them. For a sit down meal, the best places to eat in Cahir covers the restaurants, Sunday lunch in Cahir covers the carvery end of it and takeaway food in Cahir covers the rest. During the day, cafes in Cahir is the coffee list.
Getting there and getting home
Cahir sits on the M8 and the N24, and the town centre pubs are a short walk from the bus stops. The Square has on street parking if you drive, though in a town this compact the car is dead weight after the first stop. Evening public transport is thinner than you would like: getting to Cahir is easier than getting out of it late at night, so check what is running before you count on it.
Pubs close and pubs change hands. Everything above was trading when the page was written, and where a pub keeps a Facebook page that will be more current than this one, and will tell you whether there is music on.