esp-idf/examples/storage/spiffs/README.md

SPIFFS example

This example demonstrates how to use SPIFFS with ESP32. Example does the following steps:

1. Use an "all-in-one" esp_vfs_spiffs_register function to:
   • initialize SPIFFS,
   • mount SPIFFS filesystem using SPIFFS library (and format, if the filesystem can not be mounted),
   • register SPIFFS filesystem in VFS, enabling C standard library and POSIX functions to be used.
2. Create a file using fopen and write to it using fprintf.
3. Rename the file. Before renaming, check if destination file already exists using stat function, and remove it using unlink function.
4. Open renamed file for reading, read back the line, and print it to the terminal.

Example output

Here is an example console output. In this case format_if_mount_failed parameter was set to true in the source code. SPIFFS was unformatted, so the initial mount has failed. SPIFFS was then formatted, and mounted again.

I (195) example: Initializing SPIFFS
E (195) SPIFFS: mount failed, -10025. formatting...
I (4525) example: Opening file
I (4635) example: File written
I (4685) example: Renaming file
I (4735) example: Reading file
I (4735) example: Read from file: 'Hello World!'
I (4735) example: SPIFFS unmounted