1
用户态 Shell：用户进程 → fork → exec → 命令程序
2
内核态 Shell：内核线程 → 直接调用内核 API

1
// 在 main() 函数中创建 Shell 任务
2
task_create_kernel("shell", shell_task, NULL, 5);
3

4
// Shell 任务的主函数
5
static void shell_task(void *arg)
6
{
7
    while (1) {
8
        // 显示提示符
9
        vga_printf("%s> ", cwd);
10

11
        // 读取用户输入
12
        // 解析命令
13
        // 执行命令
14
    }
15
}

1
static int parse_command(char *line, char *argv[])
2
{
3
    int argc = 0;
4
    char *p = line;
5

6
    // 跳过前导空白
7
    while (*p && argc < MAX_ARGS - 1) {
8
        while (*p == ' ' || *p == '\t') p++;
9
        if (!*p) break;
10

11
        // 记录参数起始位置
12
        argv[argc++] = p;
13

14
        // 找到参数结束位置
15
        while (*p && *p != ' ' && *p != '\t') p++;
16

17
        // 用空字符分隔参数
18
        if (*p) *p++ = '\0';
19
    }
20
    argv[argc] = NULL;
21
    return argc;
22
}

1
typedef struct {
2
    const char *name;
3
    void (*func)(int argc, char *argv[]);
4
} builtin_t;
5

6
static builtin_t builtins[] = {
7
    {"help",    cmd_help},
8
    {"echo",    cmd_echo},
9
    {"ls",      cmd_ls},
10
    {"cat",     cmd_cat},
11
    {"mkdir",   cmd_mkdir},
12
    {"touch",   cmd_touch},
13
    {"write",   cmd_write_file},
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    {"pwd",     cmd_pwd},
15
    {"cd",      cmd_cd},
16
    {"ps",      cmd_ps},
17
    {"mem",     cmd_mem},
18
    {"uptime",  cmd_uptime},
19
    {"history", cmd_history},
20
    {"version", cmd_version},
21
    {NULL, NULL}
22
};

1
#define HISTORY_SIZE  8
2

3
static char *history[HISTORY_SIZE];
4
static int hist_count = 0;
5

6
static void execute_command(char *line)
7
{
8
    // 保存到历史
9
    if (line[0] && hist_count < HISTORY_SIZE) {
10
        history[hist_count] = (char *)kmalloc(strlen(line) + 1);
11
        if (history[hist_count]) {
12
            strcpy(history[hist_count], line);
13
            hist_count++;
14
        }
15
    }
16
    // 执行命令...
17
}

1
static void cmd_history(int argc, char *argv[])
2
{
3
    (void)argc; (void)argv;
4
    for (int i = 0; i < hist_count; i++) {
5
        vga_printf("  %d: %s\n", i + 1, history[i]);
6
    }
7
    if (hist_count == 0) vga_printf("  (empty)\n");
8
}

1
17.shell/
2
├── boot/
3
│   ├── mbr.S          # MBR 引导程序
4
│   └── loader.S       # 加载器
5
├── kernel/
6
│   ├── include/       # 头文件
7
│   ├── kernel.c       # Shell 实现文件
8
│   ├── fs/            # 文件系统
9
│   ├── drivers/       # 设备驱动（键盘驱动）
10
│   └── ...            # 其他内核模块
11
└── Makefile           # 构建配置

1
// 命令缓冲区
2
#define CMD_BUF_SIZE  256
3
#define MAX_ARGS      16
4
#define HISTORY_SIZE  8
5

6
// Shell 状态
7
static char cmd_buffer[CMD_BUF_SIZE];  // 命令输入缓冲区
8
static int cmd_pos = 0;                 // 当前输入位置
9
static char *history[HISTORY_SIZE];     // 命令历史
10
static int hist_count = 0;              // 历史条目数量
11
static char cwd[64] = "/";              // 当前工作目录

1
cd 17.shell
2
make clean && make all && make run

1
=== Chapter 17: Shell ===
2

3
MyOS Shell v1.0
4
Type 'help' for available commands.
5

6
/> help
7
Available commands:
8
  help     - Show this help
9
  clear    - Clear screen
10
  echo     - Print arguments
11
  ls [dir] - List directory
12
  cat file - Show file contents
13
  mkdir d  - Create directory
14
  touch f  - Create empty file
15
  write f  - Write text to file
16
  pwd      - Print working directory
17
  cd dir   - Change directory
18
  ps       - List tasks
19
  mem      - Memory info
20
  uptime   - System uptime
21
  history  - Command history
22
  version  - System version
23
  exit     - Halt system
24

25
/> ls /
26
  home/
27
  bin/
28
  readme.txt
29

30
/> cat /readme.txt
31
Welcome to MyOS!
32
This is a teaching operating system.
33
Type 'help' in the shell for commands.
34

35
/> mkdir /home/user
36
/> touch /home/user/test.txt
37
/> write /home/user/test.txt Hello World
38
/> ls /home/user
39
  test.txt
40

41
/> cat /home/user/test.txt
42
Hello World
43

44
/> cd /home
45
/> pwd
46
/home
47

48
/> history
49
  1: help
50
  2: ls /
51
  3: cat /readme.txt
52
  4: mkdir /home/user
53
  5: touch /home/user/test.txt
54
  6: write /home/user/test.txt Hello World
55
  7: ls /home/user
56
  8: cat /home/user/test.txt
57
  9: cd /home
58
  10: pwd
59
  11: history
60

61
/> uptime
62
Uptime: 12 seconds (1200 ticks)
63

64
/> version
65
MyOS v1.0 - Teaching Operating System
66
Chapter 17: Shell Implementation
67

68
/> exit
69
Shutting down...

1
#define HISTORY_SIZE  8