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

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| Supported Targets | ESP32 | ESP32-C3 | ESP32-C6 | ESP32-S2 | ESP32-S3 |
| ----------------- | ----- | -------- | -------- | -------- | -------- |
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# SPIFFS example
(See the README.md file in the upper level 'examples' directory for more information about examples.)
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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.
SPIFFS 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.
## How to use example
### Hardware required
This example does not require any special hardware, and can be run on any common development board.
### Configure the project
* Open the project configuration menu (`idf.py menuconfig`)
* Configure SPIFFS settings under "SPIFFS Example menu". See note about `esp_spiffs_check` function on [SPIFFS Filesystem](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/storage/spiffs.html) page.
### Build and flash
Replace PORT with serial port name:
```
idf.py -p PORT flash monitor
```
(To exit the serial monitor, type ``Ctrl-]``.)
See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
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## 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 (324) example: Initializing SPIFFS
W (324) SPIFFS: mount failed, -10025. formatting...
I (19414) example: Partition size: total: 896321, used: 0
I (19414) example: Opening file
I (19504) example: File written
I (19544) example: Renaming file
I (19584) example: Reading file
I (19584) example: Read from file: 'Hello World!'
I (19584) example: SPIFFS unmounted
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```
To erase the contents of SPIFFS partition, run `idf.py erase-flash` command. Then upload the example again as described above.