The widely used ifconfig is missing from Centos 7.X version of Linux with minimal install. To get it back, run the following command:
yum install net-tools
The command will then be available as usual.
If you don't want to use ifconfig and are wondering how else you can find the IP address, you can run this command:
Due to some corruption issue during ubuntu (and ubuntu based sytems), this error may come up:
apt: relocation error: /usr/lib/x86_64-linux-gnu/libapt-private.so.0.0: symbol _ZN9pkgSystem9LockInnerEv, version APTPKG_5.0 not defined in file libapt-pkg.so.5.0 with link time reference
There's no clear answer on how to fix this or why it happens, but it corrupts the file libapt-private.so.0.0.0. One way to resolve the issue is to copy the file from another ubuntu 16.04 install. (Or you can download it from here: libapt-private.so.0.0.0 version x64)