battery-level

This utility reports on the remaining battery percentage and charging status of macOS-based computers. It is intended to be incorprated into shell prompts, terminal-based editor status-lines, scripts, etc.

Usage

Macs can have multiple power sources (though it's rare). Use the --list flag to tell you how many sources you have, and then --index:<num> to select the source you want. Note that it is a zero-based array, so if you have one source, then use --index:0. The default output is the percentage of battery remaining.

$ battery-level --list
1
$ battery-level --index:0
48

There is also a handy --default flag to automatically select the first source.

$ battery-level --default
48

You can pass the flag --charging, which will return 1 if the battery is currently charging, and 0 if it is not. Cases where it will return 0 include when the computer is not plugged in, as well as when it is plugged in but the battery is full.

Both of these result in the same output:

$ battery-level --index:0 --charging
0
$ battery-level --default --charging
0

Example Shell Integration

You can put the following in your ~/.bashrc

prompt_battery() {
  charge=$(battery-level --default --charging)
  if [[ $charge -eq 1 ]]; then
    echo '⚡️'
  fi
}

export PS1="\$(prompt_battery) \d \@ \w $ "

And, if the battery is charging, your prompt will look like

⚡️  Mon Feb 27 10:18 AM ~/Development/battery-level $