Hi, I mention my problem:
I have some txt files in an sd, I want (for now) that the user to be able to type an entire variable (1,2,3,4) in the serial monitor and depending on which variable it is, open and show the file in question (in the serial monitor too), I appreciate if you can help me, I'm a bit new in the management of sd.
First of all: Serial.parseInt() (https://www.arduino.cc/reference/en/language/functions/communication/serial/parseint/)
Then you'll have to somehow map those numbers to their corresponding file names, either by a lookup table or by a pattern in the naming (e.g. "FILE0001.txt").