So I know tools exist for this problem because I've heard about them, but I don't know what they are.
I want to do something like filter out all data but the usernames in /etc/passwd.
For example, I would want to grab user1, user2, and user3 from the following file. In this case, the logic could be "Grab text up to the first ':' on each line of the file".
user1:x:1:4 user2:x:2:5 user3:x:3:6
The output would be:
user1 user2 user3