文件系统读操作read

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


#define  STD_FILE_INPUT		0
#define  STD_FILE_OUTPUT	1
#define  STD_FILE_ERROR		2

int main(int argc, char* argv[]){

	char data[256] = {0};

	int nread = read(STD_FILE_INPUT, data, sizeof(data));

	const char * err_read_msg = "an read error occurred";

	if(nread == -1){

		write(STD_FILE_ERROR, err_read_msg, sizeof(err_read_msg)/sizeof(err_read_msg[0]));
	}

	const char* err_write_msg = "an write error occurred";

	printf("\n");
	if(nread != write(STD_FILE_OUTPUT, data, nread)){

		write(STD_FILE_ERROR, err_write_msg, sizeof(err_read_msg)/sizeof(err_read_msg[0]));
	}

	return 0;
}