File Sensor

The file sensor platform reads the entries from a plain-text file and shows the found value. Only the last line of the file is used. This is similar to do $ tail -n 1 sensor.txt on the command-line. Note that file paths must be added to whitelist_external_dirs.


To enable the file sensor, add the following lines to your configuration.yaml:

# Example configuration.yaml entry
  - platform: file
    file_path: /home/user/.homeassistant/sensor-data.txt

Configuration variables:

  • file_path (Required): path to file that stores the sensor data.
  • name (Optional): Name of the sensor to use in the frontend. Defaults to File.
  • unit_of_measurement (Optional): Defines the units of measurement of the sensor, if any.
  • value_template (Optional): Defines a template to extract a value from the payload.


In this section you find some real life examples of how to use this sensor.

Entries as JSON

Assuming that the log file contains multiple values formatted as JSON like shown below:

{"temperature": 21, "humidity": 39}
{"temperature": 22, "humidity": 36}

This would require the following entry in the configuration.yaml file to extract the temperature:

# Example configuration.yaml entry
  - platform: file
    name: Temperature
    file_path: /home/user/.homeassistant/sensor.json
    value_template: '{{ value_json.temperature }}'
    unit_of_measurement: '°C'