实现简易版shell

操作系统小组作业，实现一个简易shell，shell实现了下列命令

exit------退出终端命令

clr-------清屏命令

time-----时间命令

myshell----欢迎命令

quit-----终止命令

pwd-----路径命令

cat-----查看文件命令

help---帮助命令

help [参数]---查看某个具体的命令的注释

ls -l-----查看目录下的文件命令

只实现了简单的几个命令，仅做参考,代码如下

 #include<bits/stdc++.h>
 #include<unistd.h>
 #include<stdio.h>
 #include<sys/types.h>
 #include<pwd.h>
 #include<time.h>
 #include<dirent.h>
 #include<stdlib.h>
 #include<sys/stat.h>
 #include<fcntl.h>
 #include <grp.h>
   #include <sys/wait.h>
 #include<memory.h>
 using namespace std;
 #define MAX_LINE 80
 #define MAX_NAME_LEN 50
 #define MAX_PATH_LEN 1000
 int cmd_cnt;
 char *cmd_array[MAX_LINE/+];
 string st;
 void mytime(){
     int weekday;
     int month;
     time_t tvar;
     struct tm *tp;
     time(&tvar);
     tp=localtime(&tvar);//获取本地时间
     weekday=tp->tm_wday;
     switch(weekday){//根据不同的值打印不同的星期
     case :
         printf("Mon ");
         break;
     case :
         printf("Tues ");
         break;
     case :
         printf("Wed ");
         break;
     case :
         printf("Thur ");
         break;
     case :
         printf("Fri ");
         break;
     case :
         printf("Sat ");
         break;
     case :
         printf("Sun ");
         break;
     default:
         break;
     }
     month=+tp->tm_mon;//必须要加1，经过查阅资料：tm_mon比实际的值少了1
     switch(month){//根据不同的值打印月份名
     case :
         printf("Jan ");
         break;
     case :
         printf("Feb ");
         break;
     case :
         printf("Mar ");
         break;
     case :
         printf("Apr ");
         break;
     case :
         printf("May ");
         break;
     case :
         printf("Jun ");
         break;
     case :
         printf("Jul ");
         break;
     case :
         printf("Aug ");
         break;
     case :
         printf("Sep ");
         break;
     case :
         printf("Oct ");
         break;
     case :
         printf("Nov ");
         break;
     case :
         printf("Dec ");
         break;
     default:
         break;
     }
     printf("%d ",tp->tm_mday);//日期
     printf("%d:",tp->tm_hour);//小时
     printf("%d:",tp->tm_min);//分钟
     printf("%d ",tp->tm_sec);//秒
     printf("CST ");//CST，意思是China Standard Time
     printf("%d\n",+tp->tm_year);//必须加上1900，返回的值并不是完整的年份，比真实值少了1900
 }
 void welcome(){
     //如下是欢迎信息
     //为了是程序更友好，加入了颜色
     //颜色是紫色，背景色与shell相同
     printf("\e[32mwelcome to myshell\e[0m\n");
     printf("\e[32mit's a Lunix-like shell program made by us\e[0m\n");
     printf("\e[32mhope you have a good time with it :-)\e[0m\n");
 }
 void mypwd(){
     char pathname[MAX_PATH_LEN];
     if(getcwd(pathname,MAX_PATH_LEN)){//获取路径名
         printf("%s\n",pathname);
     }
     else{//如果出错
         perror("myshell: getcwd");//报错
         exit();
     }
 }

 void myquit(){
     printf("Thanks for your using，bye-bye！\n");
     sleep();//暂停1s，看上去视觉效果好一些
     exit();
 }
 void exit(){
    exit();
 }
 void myclr(){
     cout << "\033[2J";
     cout << "\033[H";

 }

 void printprompt(){//实现命令提示符

     char hostname[MAX_NAME_LEN];
     char pathname[MAX_PATH_LEN];
     struct passwd *pwd;
     pwd=getpwuid(getuid());
     gethostname(hostname,MAX_NAME_LEN);
     printf("\e[34m%s@%s:\e[0m",pwd->pw_name,hostname);

         printf("$");

 }

 //*****************************************************获得文件权限属性
 void getPower(mode_t mod)
 {
   for(int n=; n>=; n--)
   {
       if(mod&(<<n))//移位运算,1左移位n位
       {
           switch(n%)
           {
           case :
               printf("r");
               break;
           case :
               printf("w");
               break;
           case :
               printf("x");
               break;
           default:
               break;
           }
       }
       else
       {
           printf("-");
       }
         }
 }

 void cat(string filename){
   ifstream fin( filename);
   char  str[];
   while ( fin.getline(str,) )
   {
     cout  << str << endl;
   }
 }

 void ls(string allstr,string substr){

 /******************************ls*************************
 *
 *dirName[]   :store single filename
 *dir         :point to currnt directory
 *rent        :指针变量
 *st          :文件基本操作
 **********************************************************/

 struct stat st;
 char dirName[];

 DIR *dir;
 struct dirent *rent;//struct
 dir = opendir(".");

   if(allstr== "ls"){

     if(dir != NULL)
     {
       while((rent=readdir(dir)))
       {

         strcpy(dirName,rent->d_name);
         if (dirName[]!='.' && dirName)
         {
           cout << dirName<<'\t';
         }
       }
     }

     cout << endl;
   }
   else if(dir == NULL)
   {
       cout << "*****empty*****"<<endl;
   }
   else if(allstr != "ls -l")
   {
     cout << substr+":  "+ "unrecognized option "+"'"+allstr.substr(substr.length())+"'"<<endl;
     cout << "Try 'ls -l' "<<endl;
   }

   /******************************************ls -l*************************/

   else if(allstr == "ls -l")
   {
     while( rent = readdir(dir) )
     {
       strcpy(dirName,rent->d_name);
       if (dirName[]!='.' && dirName)
       {
         if(- != stat(rent->d_name, &st) )//get fileInfomation from filename p->d_name and save it in structure stat
         {
           getPower(st.st_mode);        //get r-w-d
           cout <<" "<<st.st_nlink<<" ";//get number of file links
           cout <<" "<<getpwuid(st.st_uid)->pw_name<<" ";//owner name
           cout <<getgrgid(st.st_gid)->gr_name<<'\t'; //group name
           cout << st.st_size<<'\t';  //get total size , in bytes

           //printf 12 char and align = left
           printf("%.12s  ",+ctime(&st.st_mtime));   //the last time of changing file
           cout << dirName;
           cout << endl;
         }
       }
     }
   }

   closedir(dir);
 }

 //****************************************************获得输入字符
 string strInput()
 {
   string str;
   string res;
   char c;
   while( (c = getchar()) != '\n')
     str += c;

   vector<string> arr;
   istringstream istr(str);
   string word;
   while(istr>>word) {
       arr.push_back(word);//添加元素到尾部
   }

   for(int i=; i<arr.size(); i++) {
     if(i != arr.size() - )
         res += arr[i]+" ";
     else
       res += arr[i];
   }

   return res;
 }
 ///////////////////////////////////////////////////////////help命令
 void print_manual(){
     printf("welcome to the manual of myshell, hope it's useful for you\n");
     printf("the following are the BUILT-IN commands supported by myshell\n");
     printf("\n");

     printf("exit:      exit                            quit the shell directly\n");
     printf("clr:       clr                             clear the screen\n");
     printf("time:      time                            show the current time in an elegant format\n");
     printf("myshell:   myshell [filename]              execute a batchfile\n");
     printf("quit:      quit                            quit the shell with thank-you\n");
     printf("pwd:       pwd                             print the current working directory\n");
     printf("help:      help/help [command]             show the manual of help/get help info of a sepcified command\n");

 }
 void print_cmdinfo(string cmdname){

      if(cmdname=="exit"){
         printf("usage:quit the shell directly\n");
         printf("options            descriptions\n");
         printf("none               see the manual,plz\n");
     }
     else if(cmdname=="pwd"){
         printf("usage:print the current working directory\n");
         printf("options            descriptions\n");
         printf("none               see the manual,plz\n");
     }
     else if(cmdname=="time"){
         printf("usage:show the current time in an elegant format\n");
         printf("options            descriptions\n");
         printf("none               see the manual,plz\n");
     }
     else if(cmdname=="clr"){
         printf("usage:clear screen\n");
         printf("options            descriptions\n");
         printf("none               see the manual,pls\n");
     }
     else if(cmdname=="myshell"){
         printf("usage:execute a batchfile\n");
         printf("options            descriptions\n");
         printf("none               see the manual,plz\n");
     }
     else if(cmdname=="help"){
         printf("usage:show the manual of help/get help info of a sepcified command\n");
         printf("options            descriptions\n");
         printf("none               see the manual,plz\n");
     }
     else if(cmdname=="quit"){
         printf("usage:quit the shell with thank-you information\n");
         printf("options            descriptions\n");
         printf("none               see the manual,plz\n");
     }
     else {//如果有错
         printf("myshell: help: Invalid use of help command\n");//打印提示信息
     }

 }
 void myhelp(){
     if(cmd_cnt==){//如果是不带参数的help
         print_manual();//调用子函数print_manual打印用户帮助手册
     }
     else if(cmd_cnt==){//如果格式是"help [command]"
         print_cmdinfo(st);//打印单个命令的帮助信息
     }

 }
 void help(string str){
  if(str=="help"){
      cmd_cnt=;
      }
      else if(str.length()>){

       cmd_cnt=;
       st=str.substr(,str.length());
      }

      myhelp();
 }
 /////////////////////////////////////////////////////////////////////////////////
 int main()
 {
   string n;
   string str1; //first str !=include space
   string str2;

   while(true){
       printprompt();
       n=strInput();

     istringstream istr(n);
     istr >> str1>>str2;

     if(str1 == "ls"){
         ls(n,str1);
         continue;
     }
       if(n=="exit")//退出
           exit();
        else if(n=="clr"){
           myclr();
        }
        else if(n=="time")
        {
            mytime();
        }
        else if(n=="myshell")
        {
            welcome();
        }
        else if(n=="quit")
        {
        myquit();
        }
        else if(n=="pwd")
        {
        mypwd();
        }
     else if(str1 == "cat"){
       cat(str2);
     }
        else if(str1=="help"){
        help(n);
        }
     else
         cout << "invaild command" << endl;

   }

   return ;
 }

如果需要的话，下面链接里面有我对该代码的部分不常见的函数和结构体的注释，如需要的可以看一下

https://files-cdn.cnblogs.com/files/henuliulei/shellzhushi.zip