#!/usr/bin/perl

@ips = ('10.1.1.11', '10.1.1.12', '10.1.1.120', '10.1.1.121', '10.1.1.13');
@new = sort {
  ($a =~ /10\.1\.1\.(\d+)/)[0] <=> ($b =~ /10\.1\.1\.(\d+)/)[0]
} @ips;
print "@new\n";
exit 0;

@new = sort {
  ($a =~ /10\.1\.(\d+)\.(\d+)/)[0] <=> ($b =~ /10\.1\.(\d+)\.(\d+)/)[0]
  ||
  ($a =~ /10\.1\.(\d+)\.(\d+)/)[1] <=> ($b =~ /10\.1\.(\d+)\.(\d+)/)[1]
} @ips;