Sorting IPv4 Addresses with GNU Sort
While processing some rather large lists of addresses as part of a side project, I needed to be able to sort them in a numerical order within a shell script. I had a file with lines like:
- 69.90.132.19
- 69.90.132.22
- 66.152.91.84
- 208.122.204.181
- 69.90.132.22
- 69.90.132.31
- 216.131.106.249
- 216.131.84.26
- 67.55.105.252
- 208.64.44.102
Standard sort using sort –n only sorts on the first octet, and although it’s a improvement on alphabetic sorting its not ideal. The solution comes in specifying a pile of switches to sort:
sort -n -t . -k 1,1 -k 2,2 -k 3,3 -k 4,4
This gets it sorted in Numerical order, by octet, using a period (dot) as a separator between octets. Combining this with a –u flag gives one a nicely sorted, unique list of IP addresses. This could probably be extended to IPv6 without too much hastle.
Tags: Networking, Unix