Shell Command: How to Intercept IP Addresses from ifconfig Output

The key to matching is a regular expression. Tools can consider grep or sed.

 

plan 1:

With grep:

ifconfig | grep -Eo 'inet (addr:)? ([0-9] * \.) {3} [0-9] *' | grep -Eo '([0-9] * \.) {3} [0-9] *' | grep -v '127.0.0.1'

 

Scenario 2:

With the help of sed:

ifconfig | sed -En 's/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p'

 Note: The -E option of sed depends on the specific sed version. If -E is invalid, use -r instead.

 

In addition, you can specify the interface to be displayed through ifconfig.

ifconfig eth0 | ...

 

In my specific practice, I used scheme 2 and specified the interface.

SERVER_IP=$(/sbin/ifconfig eth0 | sed -nr 's/.*inet (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p')

 

See also: SO