Difference between virtual interfaces with ifconfig and iproute2

Question

I am wondering what is the difference between:

# ifconfig eth0:0 1.1.1.1/24

and just

# ip addr add 1.1.1.1/24 dev eth0

Btw I cannot do

# ip addr add 1.1.1.1/24 dev eth0:0
RTNETLINK answers: File exists

In ip addr show it appears differently :

eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 
link/ether 8c:ae:4c:fe:1f:75 brd ff:ff:ff:ff:ff:ff
inet 1.1.1.1/24 brd 1.1.1.255 scope global eth0:0 ---> with ifconfig
inet 2.2.2.2/24 scope global eth0 ----> with ip

When should I prefer the first way and when should I prefer the second way? It seems more cool to

Answer 1

In Linux, use the ip commands. In other OSes, use ifconfig and family.

If you use the iproute2 way (ip) as such:

ip addr add 1.1.1.1/24 dev eth0 label eth0:0

you should have the same effect as your first ifconfig command, and should even be displayed the same way by ifconfig. As mentioned, in Linux, you should prefer the ip family of commands over ifconfig, route, etc. Though ifconfig and others will remain a stable in network admin's diets for a while to come because of their wide usage and support in non-Linux OSes as well.