This is an example how to stimulate a VHDL Testbench via a named pipe. It requires VHDL 2008 because it uses the flush-Command which was added in this version.
The repository contains an example testbench "fileio.vhdl" and a related script to compile and simulate the file in ModelSim. Further you will find a server C-program "Pipe_Server.c" for Windows. It opens one named pipe for sending stimulus data to the testbench and another named pipe to receive response data from the testbench.
It was tested with the VHDL-testbench running with Modelsim with the GCC compiled server.
I assume that it will also run on Linux with an adjusted server programm.
Have fun.