When using iproute2's ip binary, you can omit the dev parameter, e.g. ip link set up eth0 instead of ip link set up dev eth0.
This breaks if for some reason your device is named e.g. he, hel, … because it is interpreted as ip link set up help.
I just encountered this bug using networking.bridges trying to create an interface named he.
I used a grep on nixpkgs to try to find iproute2 invocations using variables without the dev keyword, and found a few, and fixed them by providing the dev keyword.
I merely fixed what I found, but the use of abbreviated commands makes it a bit hard to be sure everything has been found (e.g. ip l set … up instead of ip link set … up).
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