There are often times I will `grep -n` whatever file to find what I am looking for. Say the output is:

```
1234: whatev 1
5555: whatev 2
6643: whatev 3

```

If I want to then just extract the lines between 1234 and 5555, is there a tool to do that? For static files I have a script that does `wc -l` of the file and then does the math to split it out with tail & head but that doesn't work out so well with log files that are constantly being written to.