Linux getting all network interface names

Question

I need to collect all the interface names, even the ones that aren\'t up at the moment. Like ifconfig -a.

getifaddrs() is iterating through

Answer 1

I need the main device that is being used by the system (assuming there is only one) such as eth0 wlan0 or whatever RHEL7 is trying to do...

The best I hacked together was this:

#!/bin/bash
# -- Get me the interface for the main ip on system

for each in $(ls -1 /sys/class/net) ;do 

    result=$(ip addr show $each | awk '$1 == "inet" {gsub(/\/.*$/, "", $2); print $2}' | grep "$(hostname -I | cut -d' ' -f1)")

    if [ ! -z "${result// }" ] && [ -d /sys/class/net/${each// } ] ;then
            echo "Device: $each IP: $result"
            break;
    fi

done

Sample output:

    ./maineth.sh  
    Device: enp0s25 IP: 192.168.1.6