First init.

libraries/SD/examples/Files/Files.ino

@@ -0,0 +1,76 @@
+/*
+  SD card basic file example
+
+  This example shows how to create and destroy an SD card file.
+  The circuit. Pin numbers reflect the default
+  SPI pins for Uno and Nano models:
+   SD card attached to SPI bus as follows:
+ ** SDO - pin 11
+ ** SDI - pin 12
+ ** CLK - pin 13
+ ** CS - depends on your SD card shield or module.
+ 		Pin 10 used here for consistency with other Arduino examples
+    (for MKR Zero SD: SDCARD_SS_PIN)
+
+  created   Nov 2010
+  by David A. Mellis
+  modified 24 July 2020
+  by Tom Igoe
+
+  This example code is in the public domain.
+*/
+#include <SD.h>
+
+const int chipSelect = 10;
+File myFile;
+
+void setup() {
+  // Open serial communications and wait for port to open:
+  Serial.begin(9600);
+  // wait for Serial Monitor to connect. Needed for native USB port boards only:
+while (!Serial);
+
+  Serial.print("Initializing SD card...");
+
+  if (!SD.begin(chipSelect)) {
+    Serial.println("initialization failed. Things to check:");
+    Serial.println("1. is a card inserted?");
+    Serial.println("2. is your wiring correct?");
+    Serial.println("3. did you change the chipSelect pin to match your shield or module?");
+    Serial.println("Note: press reset button on the board and reopen this serial monitor after fixing your issue!");
+    while (1);
+  }
+  Serial.println("initialization done.");
+
+  if (SD.exists("example.txt")) {
+    Serial.println("example.txt exists.");
+  } else {
+    Serial.println("example.txt doesn't exist.");
+  }
+
+  // open a new file and immediately close it:
+  Serial.println("Creating example.txt...");
+  myFile = SD.open("example.txt", FILE_WRITE);
+  myFile.close();
+
+  // Check to see if the file exists:
+  if (SD.exists("example.txt")) {
+    Serial.println("example.txt exists.");
+  } else {
+    Serial.println("example.txt doesn't exist.");
+  }
+
+  // delete the file:
+  Serial.println("Removing example.txt...");
+  SD.remove("example.txt");
+
+  if (SD.exists("example.txt")) {
+    Serial.println("example.txt exists.");
+  } else {
+    Serial.println("example.txt doesn't exist.");
+  }
+}
+
+void loop() {
+  // nothing happens after setup finishes.
+}