1. Oracle Linux 8 Documentation: In the "Managing Core System Configuration" guide
the description of the /etc directory states it contains system configuration files. The /etc/sysconfig subdirectory is a convention in RHEL-based distributions like Oracle Linux for holding configuration files for services installed by packages. For instance
the networking service configuration is detailed in /etc/sysconfig/network-scripts/
which is provided by the network-scripts package.
Source: Oracle® Linux 8: Managing Core System Configuration
Chapter 1
"About System Configuration Files".
2. systemd Documentation (man pages): The systemd.exec(5) man page
which is part of the official Oracle Linux 8 system documentation
describes the EnvironmentFile= directive used in service unit files. This directive often points to a file in /etc/sysconfig to load service-specific configuration variables. This establishes a direct link between a service (installed by a package) and its configuration file in /etc/sysconfig.
Source: man systemd.exec
Section "EnvironmentFile="
Oracle Linux 8.
3. Red Hat Enterprise Linux 8 Documentation: As Oracle Linux is derived from RHEL
its documentation is highly relevant. The "Configuring and managing networking" guide explicitly details the role of files within /etc/sysconfig/network-scripts. The presence and content of these files depend on the network-scripts package being installed and the network interfaces configured.
Source: Red Hat Enterprise Linux 8 Documentation
"Configuring and managing networking
" Section 2.3
"Configuring an Ethernet connection using ifcfg files".