Using GNU Sort for IP Addresses
This document shows how to use the GNU sort utility to properly sort IP addresses in true number order.
The short answer. Here's the invocation that works. It's explained in the long answer that follows.
sort -n -t . -k 1,1 -k 2,2 -k 3,3 -k 4,4
The long answer. More than once I've been confronted with a list of IP addresses that I've wanted to sort into numeric order. Trouble is, the dotted-quad notation isn't sort-friendly. Consider the following raw list of addresses.
cat addresses.txt18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 184.108.40.206 220.127.116.11
Without options, sort will rely on alphabetic order, which certainly won't do what you want:
sort addresses.txt18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 184.108.40.206 220.127.116.11
There are so many mistakes in this ordering I'm not even going to try to list them all.
The situation is only marginally improved when using the
sort -n addresses.txt18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 184.108.40.206 220.127.116.11
The first set of numbers in each dotted-quad sort correctly—5 preceeds 19, and 129 is at the tail end—but the internal
numbering still gets improper treatment.
18.104.22.168 is listed prior to
22.214.171.124 because 220 is alphabetically prior to 24. Likewise the two
19.20.x.x addresses are mixed up because 203 is alphabetically prior to 21.
The solution is to tell sort to order the list numerically, considering each address as a set of four numeric fields, each separated by a dot. Below I am using nbtstat to scan my work network and using sort to sort the output appropriately.
nbtscan 126.96.36.199/16 | sort -n -t . -k 1,1 -k 2,2 -k 3,3 -k 4,4------------------------------------------------------------------------------ IP address NetBIOS Name Server User MAC address Doing NBT name scan for addresses from 188.8.131.52/16 184.108.40.206 INTZ-DHCP
INTZADM 00-d0-b7-58-dc-18 220.127.116.11 INTZ-DNS02 INTZ-DNS02 00-d0-b7-58-e0-ab 18.104.22.168 VMSERVER ADMINISTRATOR 00-00-b4-98-1a-e6 22.214.171.124 PLUTO 00-d0-b7-83-17-ca 126.96.36.199 KOIOS SHART 00-03-47-a5-1a-04 188.8.131.52 BARCODE-WKSTN RSCHAFFNER 00-b0-d0-76-fd-e2 184.108.40.206 INTRUSIO-M77QUC GHEMPHILL 00-01-03-82-db-e2 220.127.116.11 RIMDEMO 00-03-47-a5-92-0d 18.104.22.168 BBITTLE-LT 00-11-43-3b-6f-51
In English, you're saying, Yo, sort! I've got here a list of
-n), but each item in the list consists of some subnumbers, fields set apart from the
others by a dot (
-t .). Sort first by the first field, and only the first field (
-k 1,1), then by the second and only the second (
-k 2,2), and so on (
-k 3,3 -k 4,4).