Document environment variables in README.md

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Didier A 2023-02-15 13:33:20 +01:00 committed by GitHub
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@ -102,6 +102,17 @@ file per device in a nfc/devices.d directory:
printf 'name = "My first device"\nconnstring = "pn532_uart:/dev/ttyACM0"\n' | sudo tee /etc/nfc/devices.d/first.conf
printf 'name = "My second device"\nconnstring = "pn532_uart:/dev/ttyACM1"\n' | sudo tee /etc/nfc/devices.d/second.conf
Environment Variables
=====================
You can override certain configuration options at runtime using the following environment variables:
+ `LIBNFC_DEFAULT_DEVICE=<connstring>`: `LIBNFC_DEFAULT_DEVICE=pn532_uart:/dev/ttyACM0` will use pn532 on /dev/ttyACM0 as default device
+ `LIBNFC_DEVICE=<connstring>` will ignore all devices in the config files and use only the one defined in the variable
+ `LIBNFC_AUTO_SCAN=<true|false>` overrides `allow_autoscan` option in the config file
+ `LIBNFC_INTRUSIVE_SCAN=<true|false>` overrides `allow_intrusive_scan` option in the config file
+ `LIBNFC_LOG_LEVEL=<0|1|2|3>` overrides `log_level` option in the config file
To obtain the connstring of a recognized device, you can use `nfc-scan-device`: `LIBNFC_AUTO_SCAN=true nfc-scan-device` will show the names & connstrings of all found devices.
How to report bugs
==================