pipe-buf.c

#define _GNU_SOURCE
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

int main() {
        mkfifo("test-fifo", 0660);
        printf("fifo PIPE_BUF: %ld\n", pathconf("test-fifo", _PC_PIPE_BUF));
        unlink("test-fifo");

        int fd[2];
        pipe(fd);
        printf("pipe PIPE_BUF: %d\n", fcntl(fd[0], F_GETPIPE_SZ));

        return 0;
}