bGain

bgain [-h] [-o] [-c <path to config>]

Retrieves your latest blood glucose and the change since your last reading from your Nightscout server. Publishes a string containing both, along with a trend arrow, to a temporary file in your filesystem. Repeats after an interval approximately matching the interval at which your server gets readings.

This program is intended to facilitate placing a blood glucose indicator on your desktop, a status bar, or in your own programs. Your script can simply read from the temporary file. bGain will make sure that the file is up-to-date.

Rust and Cargo are required to compile bGain. To install, clone the repository, then run the following in its directory:

$ make install
$ make service # if you use systemd

You must configure bGain with your server’s URL and access token. By default, bGain reads configuration from ~/.config/bgain/bgain.cfg. You can copy the provided bgain.def.cfg example file to that path, then insert the URL and token for your server. The example file has explanatory comments.

After installing the systemd unit file, run systemctl --user enable --now bgain to start bGain, which will run indefinitely, updating its temporary file promptly with each new reading.

Here’s an example shell script to update your X root window title with your current blood glucose:

#!/usr/bin/bash

gluc=$(cat /tmp/bgain-latest)
xsetroot -name "$gluc"

bGain uses Linux x86-64 system calls directly and will not work without modification on other operating systems or architectures. Known compatible with the API of Nightscout cgm-remote-monitor versions 14 and higher.

Run with the -h option to show help and exit. Run with the -o option to retrieve only one reading and exit. Run with the -c option and provide a file path to read configuration from any location.