纪念我的第一个Linux C程序

正点原子Linux C 应用编程 点亮LED学习代码（基于IMX6ULL开发板），教程使用的是系统调用，我使用的是标准I/O

#include "stdio.h"      //标准I/O库和printf函数需使用
#include "string.h"     //strcmp函数需使用

char tigger_file_addr[] = "/sys/class/leds/sys-led/trigger";
char brightness_file_addr[] = "/sys/class/leds/sys-led/brightness";

FILE *file1 = NULL;
FILE *file2 = NULL; 
int ret = 0;

/*
*需要给main函数传参时的写法
*argc：参数数量
*argv[]:参数储存数组
*/
int main(int argc, char *argv[])
{
    __uint8_t i = 0;

    printf("    传入参数个数=%d\n",argc);
    for(i=0; i<argc; i++)
    {
        printf("    参数%d的内容为:%s\n",i,argv[i]);
    }

    /*以可读可写方式打开文件 trigger */       
    file1 = fopen(tigger_file_addr, "r+");
    if (file1 == NULL)//文件打开失败
    {
        perror("    fopen tigger_file");
        return 1;
    }
    printf("    tigger_file open success\n");

    /*以可读可写方式打开文件 brightness */  
    file2 = fopen(brightness_file_addr, "r+");
    if (file2 == NULL)//文件打开失败
    {
        perror("    fopen brightness_file");
        return 1;
    }
    printf("    brightness_file open success\n");

    if (argc == 2)
    {
        if( (strcmp("on",argv[1]) == 0) ||  (strcmp("off",argv[1]) == 0))//如果传入参数为on/off
        {
            printf("    执行%s操作\n",argv[1]);
            ret = fwrite("none", 1, 4, file1);//将触发方式改为none
            if(ret != 4)
            {
                if(ferror(file1) != 0) 
                    printf("    write none to tigger_file error!\n");

                return 1;
            }
            else 
                printf("    write none to tigger_file success!\n");

            fclose(file1);//关闭trigger文件

            if( strcmp("on",argv[1]) == 0)//如果传入参数为on
            {
                ret = fwrite("1", 1, 1 ,file2);//要写入的字符串、每个数据项的大小，数据项的数量 
                if(ret != 1)
                {
                    if(ferror(file2) != 0)
                        printf("    write 1 to brightness_file error!\n");
            
                    return 1;
                }
                else
                    printf("    write 1 to brightness_file success!\n");  
            }
            else
             {
                ret = fwrite("0", 1, 1 ,file2);//要写入的字符串、每个数据项的大小，数据项的数量 
                if(ret != 1)
                {
                    if(ferror(file2) != 0)
                        printf("    write 0 to brightness_file error!\n");
            
                    return 1;
                }
                else
                    printf("    write 0 to brightness_file success!\n");  
            }           
            fclose(file2);//关闭brightness文件
        }   
        else if( strcmp("heartbeat",argv[1]) == 0)//如果传入参数为on
        {
            printf("    执行%s操作\n",argv[1]);
            ret = fwrite("heartbeat", 1, 9, file1);//将触发方式改为none
            if(ret != 9)
            {
                if(ferror(file1) != 0)
                    printf("    write heartbeat to brightness_file error!\n");
        
                return 1;
            }
            else
                printf("    write heartbeat to brightness_file success!\n");  

            fclose(file1);//关闭trigger文件
            fclose(file2);//关闭brightness文件
        }    
    }
    return 0;
}