Question

Does anyone know how to set an int file descriptor buffer to no buffer and to flush immediately? I’ve tried to use setvbuf but it takes a FILE* not int fd.

Kevin

Answer 1

A file associated with an int is an operating system handle. setvbuf() manages buffers with a C runtime library FILE.

To prevent buffering, you would have to use the proper operating system specific function, which perhaps can be done when the file is opened. For example, on Linux

int fd = open ("/dev/whatever", O_APPEND | O_WRONLY | O_DIRECT);

To flush data already written, use fsync():

#include <unistd.h>

...
fsync(fd);