Have you had experience interacting with system calls at the operating system level?

Yes, experience with system calls at the operating system level typically involves using functions provided by the OS to manage processes, files, memory, and other resources. In C/C++, these can be POSIX API calls such as open(), read(), write(), fork(), exec(), mmap(), and others.

Example of using a system call to open a file:

#include <fcntl.h>
#include <unistd.h>

int fd = open("file.txt", O_RDONLY);
if (fd == -1) {
    // error handling
}
// reading from the file
char buffer[100];
ssize_t bytesRead = read(fd, buffer, sizeof(buffer));
close(fd);

This experience allows working closer to the OS level, providing more fine-grained control over resources.