Check file handle in C using system calls

chp2/fopenflags.c

@@ -0,0 +1,30 @@
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+
+int main(void)
+{
+	int fd;
+	fd = open("test.txt", O_CREAT | O_EXCL);
+	if (fd == -1)
+		perror("First open");
+	close(fd);
+
+	fd = open("test.txt", O_CREAT | O_EXCL);
+	if (fd == -1)
+		perror("Second open");
+	close(fd);
+
+	fd = open("test.txt", O_CREAT | O_EXCL);
+	if (fd == -1)
+		perror("Third open");
+	close(fd);
+	
+	fd = open("test.txt", O_CREAT);
+	if (fd == -1)
+		perror("Fourth open");
+	close(fd);
+
+	return 0;
+}