how to remove lines from file that don't match regex?

Question

I have a big file that looks like this:

7f0c41d6-f9c6-47aa-a034-d40bc629c973.csv
159890
159891
24faaed6-62ee-4175-8430-5d73b09911c8.csv
159907
5bad221f-25ef-44fa         


        

Answer 1

grep "\.csv$" file 

will pull out only those lines ending in .csv

Then if you want to put them in a different file;

grep "\.csv$" file > newfile