Download all of the xkcd comics

xkcd.sh

#!/bin/bash

TOTAL=$(curl https://xkcd.com/info.0.json 2> /dev/null | grep -Po '"num": [0-9]+' | grep -Po '[0-9]+')

# download JSON and image file
echo "downloading ..."
for i in $(seq 1 $TOTAL)
do
	echo -ne "\r$i/$TOTAL"

	URL=https://xkcd.com/$i/info.0.json
	JSON=$(curl $URL 2> /dev/null)
	IMG=$(echo $JSON | grep -Po '"img":\s"https:\/\/imgs.xkcd.com\/comics\/[\w\(\)-]+.(png|jpg|gif)"' | grep -Po 'https://imgs.xkcd.com\/comics\/[\w\(\)-]+.(png|jpg|gif)' | sed 's/\\//g')
	TYPE=$(echo $IMG | grep -o "...$")
	NUM=$(echo $JSON | grep -Po '"num": [0-9]+' | grep -Po '[0-9]+')

	echo $JSON > "$NUM.json"
	wget $IMG -O "$NUM.$TYPE" 2> /dev/null
done
echo

# verification, there should be 2 files for each comic (JSON, image)
echo "verifiying ... (some don't have an image (404, 1446, 1608, 1663), so a small amount of errors being reported is ok)"
for i in $(seq 1 $TOTAL)
do
	echo -ne "\r$i/$TOTAL"

	if [[ $(ls $i.* 2> /dev/null | wc -l) -lt 2 ]]
	then
		echo -e "\rerror at $i"
	fi
done
echo

exit 0

I think by combining your script with @WJH's script will make the file name more detailed and easy to remember.
From 1434.jpg and 1434.json to xkcd 1434: Where Do Birds Go.jpg and xkcd 1434: Where Do Birds Go.json

https://gist.github.com/dikiaap/96b9725f8c55d52b603d773de90fd3dd