FS

open man 2 open

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

main(){
	int fd;
	char *leds = "/dev/leds";
	char *test1 = "/bin/test1";
	char *test2 = "/bin/test2";

	if((fd = open(leds,O_RDWR|O_NOCTTY|O_NDELAY))<0){
		printf("open %s failed!\n",leds);
	}
		printf("\n%s fd is %d\n",leds,fd);

	if((fd = open(test1,O_RDWR,0777))<0){
		printf("open %s failed!\n",test1);
	}
		printf("%s fd is %d\n",test1,fd);

	if((fd = open(test2,O_RDWR|O_CREAT,0777))<0){
		printf("open %s failed!\n",test2);
	}
		printf("%s fd is %d\n",test2,fd);
}

create

// 标准输入输出头文件
#include <stdio.h>

// 文件操作函数头文件
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

main()
{
	int fd;
	// 开发板中已经存在/dev/leds文件
	char *leds = "/dev/leds";
	// 开发板中不存在的文件/bin/test1
	char *test1 = "/bin/test1";
	// 开发板中不存在的文件/bin/test2
	char *test2 = "/bin/test2";
	// 需要新建的文件/bin/test3
	char *test3 = "/bin/test3";

	// 使用open函数打开文件
	if ((fd = open(leds, O_RDWR | O_NOCTTY | O_NDELAY)) < 0)
	{
		printf("open %s failed\n", leds);
	}
	printf("%s fd is %d\n", leds, fd);
	// 使用open函数打开不存在的文件，不添加O_CREAT标识符，会报错
	if ((fd = open(test1, O_RDWR)) < 0)
	{
		printf("open %s failed\n", test1);
	}
	// 打开文件创建文件，添加标志位O_CREAT表示不存在这个文件则创建文件
	if ((fd = open(test2, O_RDWR | O_CREAT, 0777)) < 0)
	{
		printf("open %s failed\n", test2);
	}
	printf("%s fd is %d\n", test2, fd);

	fd = creat(test3, 0777);
	if (fd = -1)
	{
		printf("%s fd is %d\n", test3, fd);
	}
	else
	{
		printf("create %s is succeed\n", test3);
	}
}

write

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>

main()
{
	int fd;
	char *testwrite = "/bin/testwrite";
	ssize_t length_w;
	char buffer_write[] = "Hello Write Function!";

	if ((fd = open(testwrite, O_RDWR | O_CREAT, 0777)) < 0)
	{
		printf("open %s failed\n", testwrite);
	}

	length_w = write(fd, buffer_write, strlen(buffer_write));
	if (length_w == -1)
	{
		perror("write");
	}
	else
	{
		printf("Write Function OK!\n");
	}
	close(fd);
}

read

// 标准输入输出头文件
#include <stdio.h>

// 文件操作函数头文件
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>

#define MAX_SIZE 1000

main()
{
	int fd;
	ssize_t length_w, length_r = MAX_SIZE, ret;
	char *testwrite = "/bin/testwrite";
	char buffer_write[] = "Hello Write Function!";
	char buffer_read[MAX_SIZE];

	if ((fd = open(testwrite, O_RDWR | O_CREAT, 0777)) < 0)
	{
		printf("open %s failed!\n", testwrite);
	}
	length_w = write(fd, buffer_write, strlen(buffer_write));
	if (length_w == -1)
	{
		perror("write");
	}
	else
	{
		printf("Write Function OK!\n");
	}
	close(fd);

	if ((fd = open(testwrite, O_RDWR | O_CREAT, 0777)) < 0)
	{
		printf("open %s failed!\n", testwrite);
	}
	if (ret = read(fd, buffer_read, length_r))
	{
		perror("read");
	}
	printf("Files Content is %s \n", buffer_read);
	close(fd);
}

argvc

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

// argument count变元计数
// argument value变元值
int main(int argc, char *argv[])
{
	int i, j;
	i = atoi(argv[1]);
	j = atoi(argv[2]);

	printf("the Program name is %s\n", argv[0]);

	printf("The command line has %d argument:\n", argc - 1);

	printf("%d,%d\n", i, j);

	return 0;
}

ioctl led

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define LED_NUM 2
#define LED_C 2
// cmd为0，则灭，为1，则亮；
// io为0则是靠近蜂鸣器的小灯，为1则靠近独立按键的小灯
int main(int argc, char *argv[])
{
	int fd, led_num, led_c;
	char *leds = "/dev/leds";

	led_num = LED_NUM;
	led_c = LED_C;

	printf("argv1 is cmd;argv2 is io \n");
	// 对传入的参数进行判断，超出范围直接退出
	if (atoi(argv[1]) >= led_c)
	{
		printf("argv1 is 0 or 1）");
		exit(1);
	}
	if (atoi(argv[2]) >= led_num)
	{
		printf("argv2 is 0 or 1）");
		exit(1);
	}
	// 使用ioctl函数将参数传入内核
	if ((fd = open(leds, O_RDWR | O_NOCTTY | O_NDELAY)) < 0)
		printf("open %s failed\n", leds);
	else
	{
		ioctl(fd, atoi(argv[1]), atoi(argv[2]));
		printf("ioctl %s success\n", leds);
	}
	close(fd);

	return (1);
}

ioctl buzzer

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>

#define BUZZER_C 2
int main(int argc, char *argv[])
{
	char *buzzer_ctl = "/dev/buzzer_ctl";
	int fd, ret, buzzer_c;

	buzzer_c = BUZZER_C;

	if (atoi(argv[1]) >= buzzer_c)
	{
		printf("argv[1] is 0 or 1\n");
		exit(1);
	}

	if ((fd = open(buzzer_ctl, O_RDWR | O_NOCTTY | O_NDELAY)) < 0)
	{
		printf("open %s failed\n", buzzer_ctl);
		exit(1);
	}

	ret = ioctl(fd, atoi(argv[1]), atoi(argv[2]));
	close(fd);

	return 0;
}

memset adc

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <stdint.h>
#include <termios.h>
// #include <android/log.h>
// #include <sys/ioctl.h>

int main(void)
{
	int fd;
	char *adc = "/dev/adc";
	char buffer[512];
	int len = 0, r = 0;

	memset(buffer, 0, sizeof(buffer));
	printf("adc ready!\n");

	if ((fd = open(adc, O_RDWR | O_NOCTTY | O_NDELAY)) < 0)
		printf("open adc err!\n");
	else
	{
		printf("open adc success!\n");

		len = read(fd, buffer, 10);

		if (len == 0)
			printf("return null\n");
		else
		{
			r = atoi(buffer);
			r = (int)(r * 10000 / 4095); // Datas  transition to Res
			printf("res value is %d\n", r);
		}
	}
}

stat

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

#include <fcntl.h>

int main(int argc, char *argv[])
{
	struct stat groupstat;
	int fd, ret;

	if (argc < 2)
	{
		printf("\nPlease input file path\n");
		return 1;
	}

	ret = stat(argv[1], &groupstat);
	if (ret)
	{
		printf("Please make sure file path\n");
		return 1;
	}
	printf("stat function test , %s of st_ino inode is %ld\n", argv[1], groupstat.st_ino);

	fd = open(argv[1], O_RDWR | O_NOCTTY | O_NDELAY);
	if (fd < 0)
	{
		printf("Please make sure file path\n");
		return 1;
	}
	ret = fstat(fd, &groupstat);
	if (ret)
	{
		printf("Please make sure file path\n");
		return 1;
	}
	printf("fstat function test , %s of st_ino inode is %ld\n", argv[1], groupstat.st_ino);

	ret = lstat(argv[1], &groupstat);
	if (ret)
	{
		printf("Please make sure file path\n");
		return 1;
	}
	printf("lstat function test , %s of st_ino inode is %ld\n", argv[1], groupstat.st_ino);

	return 0;
}