RHEL: man page for interface configuration files

There doesn't seem to be a manpage for the interfaces config files in RHEL but the documentation can be found in:

/usr/share/doc/initscripts-*/sysconfig.txt

Look for the sections describing files /etc/sysconfig/network and /etc/sysconfig/network-scripts/ifcfg-<interface-name>

Also in your example the command whatis ifcfg returns

ifcfg (8) - simplistic script which replaces ifconfig IP managment

As you can see it refers to "section 8" - Admin tools and commands - and you can open the manpage with:

man 8 ifcfg

But be aware that it's not the manpage describing the sysconfig files ifcfg-<interface-name>. Instead it's a manpage for a command /sbin/ifcfg which is likely not what you want.

I have found it in manual docs using find / -name *ifcfg*

Please use man 5 nm-settings-ifcfg-rh.

It includes most comprehensive documents. I have spent 1 hour to find it......HAHA

RHEL documentation for network-scripts (not strictly the man page you requested, but might help)

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/s1-networkscripts-interfaces.html