Which terminal command to get just IP address and nothing else?

Question

I\'m trying to use just the IP address (inet) as a parameter in a script I wrote.

Is there an easy way in a unix terminal to get just the IP address, rather than loo

Answer 1

Few answers appear to be using the newer ip command (replacement for ifconfig) so here is one that uses ip addr, grep, and awk to simply print the IPv4 address associated with the wlan0 interface:

ip addr show wlan0|grep inet|grep -v inet6|awk '{print $2}'|awk '{split($0,a,"/"); print a[1]}'

While not the most compact or fancy solution, it is (arguably) easy to understand (see explanation below) and modify for other purposes, such as getting the last 3 octets of the MAC address like this:

ip addr show wlan0|grep link/ether|awk '{print $2}'|awk '{split($0,mac,":"); print mac[4] mac[5] mac[6]}'

Explanation: ip addr show wlan0 outputs information associated with the network interface named wlan0, which should be similar to this:

4: wlan0:  mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether dc:a6:32:04:06:ab brd ff:ff:ff:ff:ff:ff
    inet 172.18.18.1/24 brd 172.18.18.255 scope global noprefixroute wlan0
       valid_lft forever preferred_lft forever
    inet6 fe80::d340:5e4b:78e0:90f/64 scope link 
       valid_lft forever preferred_lft forever

Next grep inet filters out the lines that don't contain "inet" (IPv4 and IPv6 configuration) and grep -v inet6 filters out the remaining lines that do contain "inet6", which should result in a single line like this one:

    inet 172.18.18.1/24 brd 172.18.18.255 scope global noprefixroute wlan0

Finally, the first awk extract the "172.18.18.1/24" field and the second removes the network mask shorthand, leaving just the IPv4 address.

Also, I think it's worth mentioning that if you are scripting then there are often many richer and/or more robust tools for obtaining this information, which you might want to use instead. For example, if using Node.js there is ipaddr-linux, if using Ruby there is linux-ip-parser, etc.

See also https://unix.stackexchange.com/questions/119269/how-to-get-ip-address-using-shell-script