Efficient way to get your IP address in shell scripts

Question

Context: On *nix systems, one may get the IP address of the machine in a shell script this way:

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

Or this way too:

ifconfig | grep 'inet' | grep -v '127.0.0.1' | awk '{print $2}' | sed 's/addr://'

Question: Would there be a more straightforward, still portable, way to get the IP address for use in a shell script?

(my apologies to *BSD and Solaris users as the above command may not work; I could not test)

Answer 1

you can do it with just one awk command. No need to use too many pipes.

$ ifconfig | awk -F':' '/inet addr/&&!/127.0.0.1/{split($2,_," ");print _[1]}'

Answer 2

you give direct interface thereby reducing one grep.

ifconfig eth0 | grep 'inet addr:' | cut -d: -f2 | awk '{print $1}'

Answer 3

Based on this you can use the following command

ip route get 8.8.8.8 | awk 'NR==1 {print $NF}'

Answer 4

Look here at the Beej's guide to networking to obtain the list of sockets using a simple C program to print out the IP addresses using getaddrinfo(...) call. This simple C Program can be used in part of the shell script to just print out the IP addresses available to stdout which would be easier to do then rely on the ifconfig if you want to remain portable as the output of ifconfig can vary.

Hope this helps, Best regards, Tom.