Could anyone give me some advices?

I need a shell script that takes an IP and inserts it into a file that contains an ordered (for human eyes) lists of IPs - 1 IP / line, followed by a mask and some comments.

List is ordered "for human eyes" I mean for example
122.0.7.x comes before 122.0.11.x


Does anyone have something like this?
Or could you tell me which is the best way to compare an IP to a list of IPs - I want to insert the new IP in the right place, I mean, if the new ip is 18.33.55.12

and the list is

...
18.33.54.9

- i want to insert it here

18.33.102.5
...

Thanks for any tips

Just echo the line into the file, then use sort (sort "file" -o "file").

Oh - seems like I wasn't so clear - sorry unSpawn.
I've tried sort but it's not exactly what I need - I mean, it sorts IPs like this:

142.xxx.xxx.xxx
15.xxx.xxx.xxx

while I would need the order "as for human eyes" i.e.

15.xxx.xxx.xxx
142.xxx.xxx.xxx

Thanks and sorry for my poorly written explanation