Use echo and Append Percentage Symbol

Instead of straightforwardly calling `cat`, I've encased the command in
`echo` to enable appending strings. This allows me to add a percentage
symbol after calling `cat "$battery"`!

This also suppresses any `echo`s for machines without battery
(i.e. a desktop environment)

Author: thekpaul

scripts/battery_percentage.sh

@@ -5,41 +5,43 @@ CURRENT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 source "$CURRENT_DIR/helpers.sh"
 
 print_battery_percentage() {
-	# percentage displayed in the 2nd field of the 2nd row
-	if is_wsl; then
-		local battery
-		battery=$(find /sys/class/power_supply/*/capacity | tail -n1)
-		cat "$battery"
-	elif command_exists "pmset"; then
-		pmset -g batt | grep -o "[0-9]\{1,3\}%"
-	elif command_exists "acpi"; then
-		acpi -b | grep -m 1 -Eo "[0-9]+%"
-	elif command_exists "upower"; then
+  # percentage displayed in the 2nd field of the 2nd row
+  if is_wsl; then
+    local battery=$(find /sys/class/power_supply/*/capacity | tail -n1)
+    if [ -n "$battery" ]; then
+      echo $(cat "$battery")%
+      return
+    fi
+  elif command_exists "pmset"; then
+    pmset -g batt | grep -o "[0-9]\{1,3\}%"
+  elif command_exists "acpi"; then
+    acpi -b | grep -m 1 -Eo "[0-9]+%"
+  elif command_exists "upower"; then
         # use DisplayDevice if available otherwise battery
-		local battery=$(upower -e | grep -E 'battery|DisplayDevice'| tail -n1)
-		if [ -z "$battery" ]; then
-			return
-		fi
-		local percentage=$(upower -i $battery | awk '/percentage:/ {print $2}')
-		if [ "$percentage" ]; then
-			echo ${percentage%.*%}
-			return
-		fi
-		local energy
-		local energy_full
-		energy=$(upower -i $battery | awk -v nrg="$energy" '/energy:/ {print nrg+$2}')
-		energy_full=$(upower -i $battery | awk -v nrgfull="$energy_full" '/energy-full:/ {print nrgfull+$2}')
-		if [ -n "$energy" ] && [ -n "$energy_full" ]; then
-			echo $energy $energy_full | awk '{printf("%d%%", ($1/$2)*100)}'
-		fi
-	elif command_exists "termux-battery-status"; then
-		termux-battery-status | jq -r '.percentage' | awk '{printf("%d%%", $1)}'
-	elif command_exists "apm"; then
-		apm -l
-	fi
+    local battery=$(upower -e | grep -E 'battery|DisplayDevice'| tail -n1)
+    if [ -z "$battery" ]; then
+      return
+    fi
+    local percentage=$(upower -i $battery | awk '/percentage:/ {print $2}')
+    if [ "$percentage" ]; then
+      echo ${percentage%.*%}
+      return
+    fi
+    local energy
+    local energy_full
+    energy=$(upower -i $battery | awk -v nrg="$energy" '/energy:/ {print nrg+$2}')
+    energy_full=$(upower -i $battery | awk -v nrgfull="$energy_full" '/energy-full:/ {print nrgfull+$2}')
+    if [ -n "$energy" ] && [ -n "$energy_full" ]; then
+      echo $energy $energy_full | awk '{printf("%d%%", ($1/$2)*100)}'
+    fi
+  elif command_exists "termux-battery-status"; then
+    termux-battery-status | jq -r '.percentage' | awk '{printf("%d%%", $1)}'
+  elif command_exists "apm"; then
+    apm -l
+  fi
 }
 
 main() {
-	print_battery_percentage
+  print_battery_percentage
 }
 main