Rename ethx and wlanx to persistent names for OpenWrt

ifrename.sh

#!/bin/sh

# ifrename.sh: rename ethx and wlanx to persistent names
# Dependency: ip ethtool
# See also: https://github.com/systemd/systemd/blob/master/src/udev/udev-builtin-net_id.c
# TODO: currently only support pci-e devices

ip -br l | cut -d' ' -f1 | while read i; do

    prefix=$(echo "$i" | cut -c-2)

    if echo $i | grep -q '@' ; then
        continue
    fi

    if [ "x$prefix" == "xet" ]; then
        prefix="en"
    elif [ "x$prefix" == "xwl" ]; then
        prefix="wl"
    else
        continue
    fi
    echo "$i:$prefix:$(ethtool -i "$i" | grep bus-info | cut -d' ' -f2)" | sed 's@[:.]@ @g'
done | while read oldname prefix domain port slot function; do
    newname=$(
        printf "%sP%dp%ds%df%d\n" $prefix "0x$domain" "0x$port" "0x$slot" "0x$function" |
        sed 's@[pP]0@@g'
    )
    echo "Rename $oldname to $newname"
    ip link set $oldname down
    ip link set $oldname name $newname
    ip link set $newname up
done