Add battery-logging systemd timer

systemd/system/log_battery.service

@@ -0,0 +1,9 @@
+[Unit]
+Description=Log the current battery charge
+Wants=log_battery.timer
+
+[Service]
+User=root
+Group=root
+Type=oneshot
+ExecStart=/usr/local/bin/log_battery.sh /org/freedesktop/UPower/devices/battery_BAT0 /home/emiliko/safe/loggers/battery/battery.csv

systemd/system/log_battery.timer

@@ -0,0 +1,11 @@
+[Unit]
+Description=Log the current battery charge
+Requires=log_battery.service
+
+[Timer]
+Unit=log_battery.service
+OnCalendar=*-*-* *:00/1:00
+RandomizedDelaySec=10s
+
+[Install]
+WantedBy=timers.target

systemd/system/timer-scripts/log_battery.sh

@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+# Look through `upower --dump` to set this variable
+declare -r BATTERY_PATH="$1"
+declare -r WRITE_PATH="$2"
+
+if [[ $# -ne 2 ]]; then
+  echo "USAGE: $(basename "$0") <battery-path> <csv-path>"
+  exit 1
+elif [[ ! -e "$WRITE_PATH" && -d "$(dirname "$WRITE_PATH")" ]]; then
+  echo "hostname,time,charge,percent,state" > "$WRITE_PATH"
+fi
+
+declare -r tmp_file="$(mktemp)"
+
+upower --dump > "$tmp_file"
+
+declare system_name="$(hostname)"
+declare current_time="$(date -u +"%Y-%m-%d %H:%M:%S UTC")"
+declare current_power="$(cat "$tmp_file" | awk '
+BEGIN { b = "'"$BATTERY_PATH"'"; t=0 }
+
+match($0, b) { t=1 }
+
+t && match($0, /energy:/) {
+  split($0,a," ")
+  print a[2]
+  exit
+}')"
+declare current_percentage="$(cat "$tmp_file" | awk '
+BEGIN { b = "'"$BATTERY_PATH"'"; t=0 }
+
+match($0, b) { t=1 }
+
+t && match($0, /percentage:/) {
+  split($0,a," ")
+  print a[2]
+  exit
+}')"
+declare current_state="$(cat "$tmp_file" | awk '
+BEGIN { b = "'"$BATTERY_PATH"'"; t=0 }
+
+match($0, b) { t=1 }
+
+t && match($0, /state:/) {
+  split($0,a," ")
+  print a[2]
+  exit
+}')"
+
+echo "$system_name,$current_time,$current_power,$current_percentage,$current_state" >> "$WRITE_PATH"