#include <unistd.h>
char *command[10];			//exec調用時存放命令的字符串數組
char curp[255];				//存放當前目錄名的數組
char input[128];			//用于輸入的數組
main(int argc,char *argv[])
{
   char *logout = "logout";
   printf("start~\n"); 
   getCommand();			//接受輸入
   do(!strcmp(logout, command[0])){	//如果命令不是louout
      getcwd(curp,255);
      printf("PWD: %s \\",curp);
      getCommand();
      if(input[0] != 0)			//如果輸入的不是空即不是直接回車的情況
      {
         exeCommand();			//執行命令
      }
   }while(strcmp(logout,&input));
}

//接受輸入
void getCommand()
{
   gets(input);	
   lineParse(input, command, " ");
}

//將一個字符串以pstrTokser為分隔符拆分為字符串數組
void lineParse(char* pstrLine,  char** pstrBuf, char* pstrToksep)                 
{   
   char*   pstrToken;   
    
   int nBuf   =   0;   
      
   pstrToken   =   strtok(pstrLine,   pstrToksep);   
   while(pstrToken   !=   NULL){   
      pstrBuf[nBuf++]   =   pstrToken;   
      pstrToken   =   strtok(NULL,   pstrToksep);   
   } 
   pstrBuf[nBuf] = NULL;  
}


void exeCommand()
{
   char comPath[50] = "/bin/";			//組調用默認目錄為bin
   if(strcmp("cd", command[0]) == 0){		//如果是cd命令
      	 if(chdir(command[1]) == -1){
            perror("change dir error");
         }
   }else{
      int pid = fork();				//分出子進程，同時父進程等待
      if(pid > 0){
         wait((int*)0);
      }else if(pid == 0){
         strcat(&comPath, command[0]);
         if(execv(comPath, command) == -1){		//執行exec調用組
            if(strcmp("logout", command[0]) == 0){
	       perror("error\n");
            }
         }
      exit(0);
   }     
}