Code showing effect when putting head -c into a redirection pipe

notes.txt

This the C source file from my test

#include "hiker.h"
#include <stdio.h>
int answer(void)
{
    for(int i = 0; i != 100; i++)
      fputs("Hello\\n", stdout);
    for(;;);
    return 6 * 7;
}

This is being compiled (gcc 10) and run from the bash script.
This is happening from inside a docker container (Debian 10).
This is inside VirtualBox being run on my MacBook Pro.
The redirected stdout/stderr are added to a tar file and gzipped to stdout.
This tgz file is captured by the Ruby program that ran the
docker container in a Process.spawn() call.
The reason for the spawn is so it can add a timeout.
Notice the 2nd to last line of the C program is an infinite loop.
The test is for whether any stdout comes back when the container times out.
The Ruby looks like this...

options = { pgroup:true, in:r_stdin, out:w_stdout, err:w_stderr }
pid = process.spawn(docker_run_cyber_dojo_sh, options)
timed_out = false
begin
  Timeout::timeout(max_seconds) { process.wait(pid) } # [C]
rescue Timeout::Error
  timed_out = true
  docker_stop_container
  kill_process_group(pid)
ensure
  tgz_out = pipe_close(r_stdout, w_stdout)
  stderr_out = pipe_close(r_stderr, w_stderr)
end
logger.write(stderr_out)
[ tgz_out, timed_out ]

Phew! This _does_ return something (Hellos) in the tgz coming back.
If I add the head filters then I get nothing coming back.