Downloading only images using curl or wget?

Question

UPDATED:

I've found using this Bash script fixes the problem of having GIF files with a .jpg extension.

---

I'm attempting to download images from a forum who's url uses the following format:

http://www.someforum.com/attachment.php&id=XXX

I wrote a bash script that uses wget to retrieve these images:

for i in {1..10}

do
    wget --accept .jpg,.jpeg --cookies=on --load-cookies=cookies.txt -p "http://www.someforum.com/attachment.php&id=${i}" -O "image${i}.jpg"

done

It works and downloads the images. However if there isn't an image it still downloads the resulting HTML and stuffs it in XX.jpg.

Curl does the same:

for i in {1..10}

do
    curl --cookie cookies.txt "http://www.someforum.com/attachment.php&id=${i}" -o "image${i}.jpg"

done

Is there anyway to reject results that are not /image/*? Right now I am assuming that the images are jpeg, it would be nice to detect the MIME/TYPE and use the appropriate filename.

Finally, wget is giving 500 response codes when an image isn't found, if I can filter 200 response codes this may yield a solution.

Bash, Ruby, Python answers are acceptable.

Answer 1

wget returns a non-zero exit code on error; it specifically sets exit status == 8 if the remote issued a 4xx or 5xx status. So, you can modify your bash loop to unlink the file if wget doesn't exit with success:

for i in {1..10}
do
    wget --accept .jpg,.jpeg --cookies=on --load-cookies=cookies.txt -p "http://www.someforum.com/attachment.php&id=${i}" -O "image${i}.jpg" || rm "image${i}.jpg"
done

Similarly, curl has a --fail option, with which it wont save the file and returns exit status 22 when the http status is >= 400.