Cicada 3301 4chan checker

4grab.sh

#!/bin/bash

# Create necessary files
hitfile=$1_hits
checkfile=$1_checkedImgs
echo -n "" > $hitfile

while :
do
	# Grab a list of images from a 4chan board
	imglist=$(curl --silent http://boards.4chan.org/$1/catalog | 
			  grep -oE '"imgurl":"[^"]+"' | 
			  sed -r "s#\"imgurl\":\"([0-9]+)\"#http://i.4cdn.org/$1/\1\.jpg#g")

	# Write checked image file if it doesn't exist
	if [ ! -f $checkfile ] ; then
		echo "$imglist" > $checkfile
		xargs -n 1 curl --silent -O < $checkfile
	else
		# Loop over all images and make sure, they
		# are in the checked images list
		for i in $imglist
		do
			grep -q $i $checkfile
			if [ $? -ne 0 ] ; then
				echo "New image: $i"
				echo $i >> $checkfile
				curl --silent -O $i
			fi
		done
	fi
	
	# Check all downloaded images for outguess/signature
	for file in *.jpg
	do
		grep -q $file $hitfile
		if [ -f $file -a $? -ne 0 ] ; then
			# Check for outguess
			outguess -r $file $file.txt
			if [ $? -eq 0 ] ; then
				# Check for valid signature
				gpg  --verify $file.txt
				if [ $? -eq 0 ] ; then
					echo $file >> $hitfile
				else
					rm $file $file.txt
				fi
			else
				rm $file $file.txt
			fi
		fi
	done
done