How to turn all network interfaces down?

Question

ifconfig -a lists all network interfaces. I need to run sudo ifconfig <iface name> down for each interface listed by the command. What is the ideal way to implement this inside a shell script?

Answer 1

You can find the name of each network interface listed by ifconfig -a in the directory /sys/class/net, which is populated by the kernel itself. Since the name of each directory in /sys/class/net is the actual name of the interface, you can loop over the files.

For Example:

for intf in /sys/class/net/*; do
    sudo ifconfig `basename $intf` down
done