The install_bigfix.sh script I have created will handle clientsettings.cfg for you automatically. It is found here: https://github.com/jgstew/tools/blob/master/bash/install_bigfix.sh
Forum post about it here: Script to kickstart the installation of BigFix on OS X, Debian-family, RHEL-family
You can download the script from GitHub’s RAW link, put it in the same folder as your clientsettings.cfg file, and it will automatically create the besclient.config file for you based upon that file. The code that just does the conversion is found here: https://github.com/jgstew/tools/blob/master/bash/convert_clientsettings.sh
If you do not provide a clientsettings.cfg file when you run install_bigfix.sh then it will automatically set the failover relay for the installed client to the relay you use to download the masthead file from. This means you don’t actually need to create the clientsettings.cfg file first for the specific endpoints if the only thing you need to do is provide the client with a relay it can reach because you provide a relay it can reach as a parameter to install_bigfix.sh
This means you could use a script to determine which relay the client should use based upon it’s DHCP IP address and then pipe that into install_bigfix.sh or always use an internet facing relay. This allows you to kickstart the BigFix client installation in a Post Install script.
You can actually use this script for Windows, Mac, and Linux: https://github.com/jgstew/tools/blob/master/CMD/install_bigfix_universal.bat
You just have to execute it with CMD on Windows and BASH on linux/mac.