If you get stranded at Udupi in the night and are looking for sleeping options you have the retiring room which has three beds. Booking for the retiring room can be done on konkanrailway.com If this you cannot get, then there is a 'boarding and lodging' hotel just opposite the station ( I am sorry but I cant remember the name)
There is a Veg Refreshment Room in the basement. There is a stair case going down right opposite the booking windows
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There is a stall selling 'ethinic' food an the platform (further away on the left side as you enter the platform #1. Serves Mirchi bhajjis, Mangaluru Bondas etc and if you are lucky you could get them hot as the frying is done in front of you. Mirchi Bajjis cost Rs 20 for 4 pieces and you can convince him to give 2 pieces for Rs 10.
Please look at the date of the magazines before you buy magazines. The stall selling magazines display the older issues while 'hiding' the latest issues
Most trains arrive at Platform #1. If you are unlucky and the train lands at platform #2, the FOB is at a high level and you may find it hard to shift to platform # 1
There is a NESTLE stall towards the Kundapura end of Platform # 1 which serves noodles, coffee and chilled mineral water. You can get a tub of noodles for Rs 25