Bash script to retrieve name of Ethernet Network interface

Solution 1:

Because all interfaces would displayed under /sys/class/, such as /sys/class/net/ listing all network interfaces,

it is possible to directly use this directly search and return the exact interface name through a simple keyword like:

ls /sys/class/net | grep enp

Solution 2:

If you want to exclude interfaces like vir , loopback and wl(wireless) then the following should do the trick.

ip link | awk -F: '$0 !~ "lo|vir|wl|^[^0-9]"{print $2;getline}'

Here we use colon as delimiter -F: then check if the row $0 does not match a certain string using regular expression.

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Solution 3:

Assuming you got only one physical interface and not some wlan interface etc. The trick is to get the interfaces. Which are in /sys/class/net and then look where they go to.

find /sys/class/net ! -type d | xargs --max-args=1 realpath  | awk -F\/ '/pci/{print $NF}'

If you got more interfaces you would have to grep lspci first:

lspci  | awk '/Ethernet/{print $1}'

The whole thing would turn into:

pci=`lspci  | awk '/Ethernet/{print $1}'`; find /sys/class/net ! -type d | xargs --max-args=1 realpath  | awk -v pciid=$pci -F\/ '{if($0 ~ pciid){print $NF}}'

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Solution 4:

I'd use ifconfig(bit old and deprecated) tool or ip command. Using ip route you are having a list of available routes. Then get only line containing default with grep and strip the unwanted characters off the string using sed

full command goes like:

ip route | grep default | sed -e "s/^.*dev.//" -e "s/.proto.*//"