iproute2: How to display the TYPE of a network devices?
The interface type information, being rarely used, is normally displayed only by adding the -details option to ip:
-d,-detailsOutput more detailed information.
So ip -details link show would display this information for all these interfaces, but also many other additional informations like:
$ ip -d link show lxcbr0
7: lxcbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
link/ether 00:16:3e:00:00:00 brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 65535
bridge forward_delay 1500 hello_time 200 max_age 2000 ageing_time 30000 stp_state 0 priority 32768 vlan_filtering 0 vlan_protocol 802.1Q bridge_id 8000.0:16:3e:0:0:0 designated_root 8000.0:16:3e:0:0:0 root_port 0 root_path_cost 0 topology_change 0 topology_change_detected 0 hello_timer 0.00 tcn_timer 0.00 topology_change_timer 0.00 gc_timer 34.76 vlan_default_pvid 1 vlan_stats_enabled 0 vlan_stats_per_port 0 group_fwd_mask 0 group_address 01:80:c2:00:00:00 mcast_snooping 1 mcast_router 1 mcast_query_use_ifaddr 0 mcast_querier 0 mcast_hash_elasticity 16 mcast_hash_max 4096 mcast_last_member_count 2 mcast_startup_query_count 2 mcast_last_member_interval 100 mcast_membership_interval 26000 mcast_querier_interval 25500 mcast_query_interval 12500 mcast_query_response_interval 1000 mcast_startup_query_interval 3124 mcast_stats_enabled 0 mcast_igmp_version 2 mcast_mld_version 1 nf_call_iptables 0 nf_call_ip6tables 0 nf_call_arptables 0 addrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
with bridge at the start of the 3rd line here.
Using JSON output along the jq command (which is a must-have tool when processing JSON from shell) allows to reliably parse the command's output, still without having to know beforehand the types, if one wants only to retrieve this information along the interface name.
$ ip -details -json link show | jq --join-output '.[] | .ifname," ",.linkinfo.info_kind,"\n"'
lo null
dummy0 dummy
dummy2 dummy
lxcbr0 bridge
wlan0 null
eth0 null
virbr0 bridge
virbr0-nic tun
tap0 tun
veth0 veth
test veth
wireguard0 wireguard
vethZ0ZQFJ veth
Real interfaces (as well as lo) have no type (ie .[].linkinfo.info_kind doesn't exist) and jq will return null for a non-existent field. It can be filtered out with this instead:
ip -details -json link show | jq --join-output '.[] | .ifname," ", if .linkinfo.info_kind != null then .linkinfo.info_kind else empty end, "\n"'
Actually, the search feature of ip link show puts together the kind and the slave kind as type, and the detailed output would show one on 3rd line, the other on 4th line. In JSON output those are two different fields: .[].linkinfo.info_kind and .[].linkinfo.info_slave_kind, so the slave types would require an other command, same for displaying both. Here's an example for both:
ip -details -json link show | jq --join-output '
.[] |
if .ifname != null then
.ifname,
" ",
if .linkinfo.info_kind != null then
.linkinfo.info_kind
else
empty
end,
" ",
if .linkinfo.info_slave_kind != null then
.linkinfo.info_slave_kind
else
empty
end,
"\n"
else
empty
end
'
which outputs instead:
lo
dummy0 dummy
dummy2 dummy
lxcbr0 bridge
wlan0
eth0
virbr0 bridge
virbr0-nic tun bridge
tap0 tun
veth0 veth
test veth
wireguard0 wireguard
vethZ0ZQFJ veth bridge
and shows here virbr0-nic being a tun (really tuntap the fact that it's tun or tap is in a sub-field) device as well as a bridge slave, and vethZ0ZQFJ a veth device as well as a bridge slave.
This same jq filter above will also cope when fed with filtered output from ip ... link show ... type ...slave when querying for slave interfaces, which apparently returns extra empty objects for non-matching interfaces, by ignoring (empty) entries without interface name. So starting the line with ip -details -json link show type bridge_slave | would return only:
virbr0-nic tun bridge
vethZ0ZQFJ veth bridge