Putting IP Address into bash variable. Is there a better way

Question

I've been struggling with this too until I've found there's a simple command for that purpose

hostname -i

Is that simple!

man hostname recommends using the --all-ip-addresses flag (shorthand -I ), instead of -i, because -i works only if the host name can be resolved. So here it is:

hostname  -I

And if you are interested only in the primary one, cut it:

hostname  -I | cut -f1 -d' '

ip is the right tool to use as ifconfig has been deprecated for some time now. Here's an awk/sed/grep-free command that's significantly faster than any of the others posted here!:

ip=$(ip -f inet -o addr show eth0|cut -d\  -f 7 | cut -d/ -f 1)

(yes that is an escaped space after the first -d)

You can take a look at this site for alternatives.

One way would be:

ifconfig  | grep 'inet addr:'| grep -v '127.0.0.1' | cut -d: -f2 | awk '{ print $1}'

A bit smaller one, although it is not at all robust, and can return the wrong value depending on your system:

$ /sbin/ifconfig | sed -n '2 p' | awk '{print $3}'

(from http://www.htmlstaff.org/ver.php?id=22346)

The ifdata command (found in the moreutils package) provides an interface to easily retrieve ifconfig data without needing to parse the output from ifconfig manually. It's achieved with a single command:

ifdata -pa eth1

Where eth1 is the name of your network interface.

I don't know how this package behaves when ifconfig is not installed. As Syncrho stated in his answer, ifconfig has been deprecated for sometime, and is no longer found on a lot of modern distributions.