Programming :: BASH Sort List By End Of Line To X Position In Each Line?

I'm trying to make another file annotation script a little speedier than it has been by the up-until-now proven method of checking the last four characters in a filename before the "dot" (eg .jpg, .psd) against a list of known IPTC categories and Exiv2 command files. It occurred to me that if one script generated a list of files in directory foo, and the same or another script sorted that list by that four-letter tag,then that list could be used(instead of a for/do/done loop on the real files in the folder) by the command-file-matching script to "vomit out" which annotator file would go with file nastynewfile.jpg, f'r'instance. The script I had been using for this task looks like this:

Code:

while read 'line';
do
sp=$(echo $line)
vc=$(echo $sp | cut -d"," -f1)
cv=$(echo $sp | cut -d"," -f2)

[code]....

Where I seem to be stuck is with how to sort the lines in templist, which may be any number of different lengths, from back to front. sort -k looked promising, except it seems only to work the other way round. I thought of invoking a

Code:

q=$(expr length $line); echo $q
n=$[q-8]; echo $n

kind of thing, but that presented the problems of how to sort by those, how to tell sort where to find them (grep?) and how to "stitch them back in" to the original list, which is what I want to sort in the first place.