1# SPIFFS example
2
3(See the README.md file in the upper level 'examples' directory for more information about examples.)
4
5This example demonstrates how to use SPIFFS with ESP32. Example does the following steps:
6
71. Use an "all-in-one" `esp_vfs_spiffs_register` function to:
8    - initialize SPIFFS,
9    - mount SPIFFS filesystem using SPIFFS library (and format, if the filesystem can not be mounted),
10    - register SPIFFS filesystem in VFS, enabling C standard library and POSIX functions to be used.
112. Create a file using `fopen` and write to it using `fprintf`.
123. Rename the file. Before renaming, check if destination file already exists using `stat` function, and remove it using `unlink` function.
134. Open renamed file for reading, read back the line, and print it to the terminal.
14
15SPIFFS partition size is set in partitions_example.csv file. See [Partition Tables](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/partition-tables.html) documentation for more information.
16
17## How to use example
18
19### Hardware required
20
21This example does not require any special hardware, and can be run on any common development board.
22
23### Build and flash
24
25Replace PORT with serial port name:
26
27```
28idf.py -p PORT flash monitor
29```
30
31(To exit the serial monitor, type ``Ctrl-]``.)
32
33See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
34
35## Example output
36
37Here 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.
38
39```
40I (324) example: Initializing SPIFFS
41W (324) SPIFFS: mount failed, -10025. formatting...
42I (19414) example: Partition size: total: 896321, used: 0
43I (19414) example: Opening file
44I (19504) example: File written
45I (19544) example: Renaming file
46I (19584) example: Reading file
47I (19584) example: Read from file: 'Hello World!'
48I (19584) example: SPIFFS unmounted
49```
50
51To erase the contents of SPIFFS partition, run `idf.py erase-flash` command. Then upload the example again as described above.
52