The simplest way (which I'm sure you've already tried, but hey, let me add it to the thread anyway) is to enter abc.dmg into the search box on the top right of any finder window, then select "File Name" from the options on the Search Bar that appears.
No need for the terminal.
Also remember that Spotlight only indexes directories specified in the Spotlight control panel and abc.dmg may not be in one of those directories.
Correct me if i'm wrong, but i think the find command needs to know what to output:
find / -name abc.dmg -print
...should print any results to the terminal (including permission errors).
If you don't want permission errors and want to search other User directories then:
sudo find / -name abc.dmg -print
1@VxJasonxV Apple questions are 100% on topic for Super User, and no real need to have every Apple question moved there. iPhone or iPad questions however will be moved when/if required. – BinaryMisfit – 2010-12-28T22:57:17.597
It wasn't so much a reason of being off-topic, but the fact that there is a more specific topic/site for this general subject. – VxJasonxV – 2010-12-28T23:57:31.957
@Diago: Has there been any discussion regarding this on meta or chat? Just wondering because AFAIK apple.SE will be launching out of beta pretty soon, so it would be nice to get everyone on the same page. – Robert S Ciaccio – 2010-12-29T00:19:47.300
1
@calavera. Fairly old discussion but relevant can be found here. Apple SE, Ubuntu SE and Linux SE is all there to compliment Super User, but in no way do we want to force users to move. I prefer asking my Apple questions here rather then Apple, since I do use 3 different operating systems. If I have a very specific question, I will ask it on a more specialized site.
– BinaryMisfit – 2010-12-29T07:22:48.637