thanks very much for the advice and info..will do.thanks again....

I'm not sure whether you can buy a paper Eurail pass in Barcelona. You could call Renfe (+34 91 232 03 20) to ask in advance.

You can buy a mobile pass anytime though, also after arriving in Spain.

As said reservations are required on some trains (extra costs), particularly in Spain, France and Italy.

Barcelona - Paris is a long journey across France so you want to make sure you can arrive safely at your destination.

Book the required reservations in advance (possible without a pass) as if they're sold out you'll have to take a slower route. Fortunately looks like plenty of seats left on a February weekday. Your itinerary will be as follows :

- TGV Barcelona-Sants - Paris Gare de Lyon 09:28 - 16:12 or 13:25 - 20:18 35€

Which day are you going to Switzerland ? There are plenty of options on this route :

- direct TGVs to Basel for 29€

- TGV to Mulhouse or Strasbourg for 10-20€ + reservation-free regional train across the border

- etc.

Fortunately reservations aren't a thing in Switzerland (and optional in the other countries). You're always allowed to board.

Questions welcome. General links (please read them!) :

https://www.seat61.com/how-to-use-a-eurail-pass.htm

https://www.seat61.com/interrail-and-eurail-reservations.htm

https://www.raileurope.com/en for reservations in and around France (desktop version, not mobile)

The pass itself you can buy a couple of hours before you travel.

Reservations are needed for some trains, otherwise you won’t be able to board. Especially the TGV Barcelona-Paris you’ll need to reserve in advance. Best do this soon. There are not a lot of trains, and these are very popular.

The rest of the trains will be okay, but all long distance trains in France (TGV) need a seat reservation. Switzerland, Germany, Austria, Belgium,… are doable without reservations as long as you don’t take night trains or Eurostars (they can be easily avoided).

planning to by a global pass on barcelona eurail aid office (barcelona sant) on the second day of arrival…(in barcelona)

for 6 eu  countries,,paris,,zurich..interlaken (switzerland)..germany..austria,,belguim,,amsterdam..

or its required to buy in advance on line…

thanks