use Cmd;
use P;
use Cmds qw(ip); # command finder that produces '$Ip' with abspath of 'ip'
my @cmd = qw( $Ip addr list );
local $_;
my %intf2addrs;
my $intf;

while ($_=Cmd->run(\@cmd)) {
  if (/^(\S+):/) {
    $intf=$1;next;
  }
  if (/^\s+inet\s([^\s]+)\s/) {
    next unless $intf;
    $int2addrs{$intf}=$1;
    P "intf %10s: %s", $intf, $1;
  }
} ...