文件系统读操作read

#include <unistd.h>#include <stdlib.h>#include <stdio.h>#define  STD_FILE_INPUT0#define  STD_FILE_OUTPUT1#define  STD_FILE_ERROR2int 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;}