Replace awk in this command

I am struggling with a preseed-script for Debian and figured out that awk is not available in the installation process. ## A little context The preseed-script fails at the following line and returns empty result:

real=ip -o link | awk '// {print $2;}' | sed s/://
cat  /etc/network/interfaces
#loopback
auto lo
iface lo inet loopback

#
auto $real
allow-hotplug $real
iface $real inet

As result, $real is empty and produces a faulty network configuration. ## What I hope to archive I'd like to rewrite the command so that the result looks like ens18 or eth0 based on this input:

root@vm:~# ip -o link
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000\    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens18:  mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000\    link/ether 1e:7d:da:55:31:23 brd ff:ff:ff:ff:ff:ff

This is the command which is failing during installation:

root@vm:~# ip -o link | awk '/1e:7d:da:55:31:23/ {print $2;}' | sed s/://
ens18

## My question How can I avoid awk and work with other tools in this situation to get the interface-name like ens18 from ip -o link-output? Unfortunately I am not that familiar with sed.