It basically consists of the small /etc/sysprofile shell script which invokes other small shell scripts having a .bash suffix which are contained in the /etc/sysprofile.d/ directory. The system administrator can drop in any script he wants without any naming convention other than that the scripts need to have a .bash suffix to enable automagic sourcing by /etc/sysprofile.
This mechanism is set up by inserting a small shell routine into /etc/profile for login shells and optionally into /etc/bashrc and/or /etc/bash.bashrc for non-login shells from where the actual /etc/sysprofile script is invoked:
if [ -f /etc/sysprofile ]; then
For using "sysprofile" under X11, one can source it in a similar way from /etc/X11/Xsession or your X display manager's Xsession file to provide the same shell environment as under the console in X11. See the example files in /usr/share/doc/sysprofile/ for illustration.
For usage of terminal emulators with a non-login bash shell under X11, take care to enable sysprofile via /etc/bash.bashrc. If not set this way, your terminal emulators won't come up with the environment defined by the scripts in /etc/sysprofile.d/.
Users not wanting /etc/sysprofile to be sourced for their environment can easily disable it's automatic mechanism. It can be disabled by simply creating an empty file called $HOME/.nosysprofile in the user's home directory using e.g. the touch(1) command.
Any single configuration file in /etc/sysprofile.d/ can be overridden by any user by creating a private $HOME/.sysprofile.d/ directory which may contain a user's own version of any configuration file to be sourced instead of the system default. It's names have just to match exactly the system's default /etc/sysprofile.d/ configuration files. Empty versions of these files contained in the $HOME/.sysprofile.d/ directory automatically disable sourcing of the system wide version.
Naturally, users can add and include their own private script inventions to be automagically executed by /etc/sysprofile at login time.
If you need a similar mechanism for executing code at logout time check out the related package syslogout(8) which is a very close companion to sysprofile.