Finding Missing Images
As part of my blog migration, I discovered one of my images wasn’t showing because it had the wrong case myimage.png vs MyImage.png. This is how I checked what other images were named wrong or missing.
My strategy is to:
- Get the list of images I have
- Find all the image referenced in the blog
- Alert where the reference name <> an actual name
Getting the list of images
This is really easy
ls /images > images_list.csv
Getting the images refereced
This is a bit trickier because I have to look inside the files. grep seems like a good way to do this.
grep -Er '/images/(.+)' _posts > referenced_images.csv
head referenced_images.csv
_posts/2014-07-31-what-version-of-php-am-i-running.md:cover: assets/images/phpapache.jpg
_posts/2011-02-17-a-tour-of-jmeter-part-1.md: You should now have two elements. 
_posts/2011-02-17-a-tour-of-jmeter-part-1.md: JMeter now has your actions recorded 
I don’t need all the info returned. ow do I just get the image name part.
looking at man grep the options -o -h look promising.
-o, --only-matching
Print only the matched (non-empty) parts of a matching line, with each such part on a separate output
line.
-h, --no-filename
Suppress the prefixing of file names on output. This is the default when there is only one file (or
only standard input) to search.
grep -Eroh '/images/(.+)' _posts > referenced_images.csv
head referenced_images.csv
/images/phpapache.jpg
/images/Record1.png)
/images/Record2.png)
/images/SBCLOptions.Png)
I’d like to just get the image name though. Pearl has a look-around assertion syntax which will check for things before or after the pattern match.
# Find a word between foo and bar
grep -oP '(?<=foo )\w+(?= bar)' test.txt
# Shortcut for the same query
grep -oP 'foo \K\w+(?= bar)' test.txt
I can modify my query to drop everything before the \K.
grep -rPoh '/images/\K.+(png|jpe?g|gif)' _posts > referenced_images.csv
head referenced_images.csv
phpapache.jpg
Record1.png
Record2.png
Nice, now I just need to loop over each one in the reference and see if there is a match in the actualls.
Finding the outlyers
I’m sure there is an easier way to do this.
while read l; do echo -n "$l "; grep -c $l image_list.csv; done < referenced_images.csv > results.csv
head results.csv
phpapache.jpg,1
Record1.png,0
Record2.png,0
trainingvalidation
cat results.csv | grep ' 0' | awk '{print $1}' > missing_images
head missing_images
Record1.png,0
Record2.png,0
CropperCapture88.png,0
Now I have my list but don’t know if it’s just missing or has a case of bad formatting.
awk '{print $1;}' missing_images
while read l; do echo -n $l,; grep -ic $l image_list.csv; done < missing_images > wrong_case.csv
head
Record1.png,1
Record2.png,1
CropperCapture%5B12%5D.png,0
# 1 means it's named wrong
# 0 means it's not in the image list
References
- Can I grep out a group match https://unix.stackexchange.com/questions/13466/can-grep-output-only-specified-groupings-that-match
- Basic Grep info https://linuxize.com/post/regular-expressions-in-grep/
