Parse ifconfig to get only my IP address using Bash

Question

I want to edit the bashrc file to have a simple function called \"myip\" to run. As you might guess, the function myip prints only my internal IP address of my machine.

Answer 1

This code outputs IP addresses for all network connections (except loopback) and is portable between most OS X and Linux versions.

It's particularly useful for scripts that run on machines where:

• The active network adapter is unknown,
• notebooks that switch between Wi-Fi and Ethernet connections, and
• machines with multiple network connections.

The script is:

/sbin/ifconfig -a | awk '/(cast)/ {print $2}' | cut -d: -f2

This can be assigned to a variable in a script like this:

myip=$(/sbin/ifconfig -a | awk '/(cast)/ {print $2}' | cut -d: -f2)

Scripts can handle possible multiple addresses by using a loop to process the results, as so:

if [[ -n $myip ]]; then
  count=0
  for i in $myip; do
    myips[count]=$i       # Or process as desired
    ((++count))
  done
  numIPaddresses=$count   # Optional parameter, if wanted
fi

Notes:

• It filters 'ifconfig' on "cast", as this has an added effect of filtering out loopback addresses while also working on most OS X and Linux versions.
• The final 'cut' function is necessary for proper function on Linux, but not OS X. However, it doesn't effect the OS X results - so it's left in for portability.