I have a bunch of files in a folder:
foo_1
foo_2
foo_3
bar_1
bar_2
buzz_1
...
I want to find all the files that do not start with a given prefix and save the list to a text file. Here is an example for the files that do have a given prefix:
find bar_* > Positives.txt
This should do the trick in any shell
ls | grep -v '^prefix'
The -v option inverts grep's search logic, making it filter out all matches. Using grep instead of find you can use powerful regular expressions instead of the limited glob patterns.