test-mkstemp.c

#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

static const char MESSAGE[] = "Hello, world!\n";

int main(void) {
	char fname[64];
	int fd;
	strcpy(fname, "/tmp/foo-XXXXXX");
	fd = mkstemp(fname);
	printf("Temp filename is '%s'\n", fname);
	write(fd, MESSAGE, sizeof(MESSAGE) - 1);
	close(fd);
	return 0;
}