UNIX for Dummies Questions & Answers

Hey everyone, I recently had to learn how to use UNIX and VIM for an internship, and have run in to a little challenge today. I have lists of thousands of file names that represent CAS (Chemical Abstracts Service) numbers, but they are not formatted correctly. CAS numbers run in the form of xxxx-xx-x, where the last two sets are always 2 and 1 digits long, respectively, but the first set of digits varies in length. My file names are just strings of numbers at the moment. Currently I have been inserting the -'s manually, but I believe VIM can automate the process. To clarify; I have a long list of strings of numbers (in either a .txt or .csv format, whichever would be more helpful) and I would like to insert a - before the last and third to last character of every line. Can this be done with a relatively simple VI command, or would writing some sort of shell script be best? I have little to no experience with scripting, so any suggestions would be helpful. Thank you!

It would be better if you posted sample input and desired output. Anyway try this in vim:

Code:

:%s/\([0-9][0-9]\)\([0-9]\)$/-\1-\2/

But I like Perl syntax more:

Code:

perl -pe 's/(\d\d)(\d)$/-$1-$2/' file

Much cleaner and more readable...

Bartus, I can't say I fully understand the command you suggested, but it did the trick wonderfully. Thank you! And in the future I will be sure to post the actual inputs and outputs I want, that slipped my mind.