Flicker-free battery monitor for OpenBSD

battmon.sh

#!/bin/sh

# Flicker-free battery monitor for OpenBSD. Requires Python 3
# One could somewhat easily rewrite the Python part in Perl if they want to use base exclusively.

BATT=acpibat0

while true; do
  RATE="$(sysctl -n hw.sensors.$BATT.power0)"
  RATE="${RATE%" ("*}"
  REMAINING="$(sysctl -n hw.sensors.$BATT.watthour3)"
  REMAINING="${REMAINING%" ("*}"
  LASTFULL="$(sysctl -n hw.sensors.$BATT.watthour0)"
  LASTFULL="${LASTFULL%" ("*}"
  DATE=$(date)
  # Don't like this python3 call? Replace the 5 lines after this comment with:
  #   TIMELEFT=$(echo "scale=2;${REMAINING%" "*}/${RATE%" "*}" | bc)
  TIMELEFT=$(python3 -c "rate='$RATE';remaining='$REMAINING';rate=float(rate.split()[0]);remaining=float(remaining.split()[0]);hr=(remaining/rate); print('{}:{:02}'.format(int(hr),int(hr*60)%60))" 2>/dev/null)
  if [[ "x$TIMELEFT" == "x" ]]; then
    # ZeroDivisionError
    TIMELEFT="N/A"
  else
    H=$(echo $TIMELEFT | cut -d: -f1)  # hours
    M=$(echo $TIMELEFT | cut -d: -f2 | cut -c1)  # highest digit of minutes
    # should match 0:00 through 0:19
    if [[ $H == 0 && ( $M == 1  || $M == 0 ) ]]; then
      echo -en '\a'
    fi
  fi
  
  print "\033[H\033[2J$DATE\nTIME LEFT: $TIMELEFT\n---\nRate:      $RATE\nRemaining: $REMAINING\nLast full: $LASTFULL"
  sleep 5
done