shell1.c

linux shell 命令解释器 通俗易懂 功能完整 可用于操作系统课程设计

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

#define COM_SIZE 20
#define COM_COUNT 10
#define INPUT_SIZE 100

int inCommand(char* str,int& flag);
int get_com(char str[]);
void initial(char arg[][COM_SIZE],char* argv[]);
int pipe_com(char* argv[]); 

int do_command(char* argv[],int& argc );
int getone(char* argv1,int ptr,char str[]);
int del_space(int ptr,char str[]);
int deal_com(char* argv[],int argc,char str[]);

void exe_com(char* argv[],int argc,int prefd[],int postfd[]);
int inFile(char* argv[],int argc);
int ppipe(char* argv[],int& argc);
int main()
{
  char c;
  char arg[COM_COUNT][COM_SIZE];
  char str[INPUT_SIZE];
  char* argv[COM_COUNT];
  int flag=0;
  int status=0;
  int argc=0;
//  char*pa;

  while(1)
  {
    initial(arg,argv);
    printf("[nenatee@localhost~]#\n");
    get_com(str);
  
    if(inCommand(str,flag)==1)//exit
    {
        exit(1);   //bug!!
    }
    else
    {
       argc=deal_com(argv,argc,str); 
   
      pid_t PID;
      PID=fork();
      if(PID==0)
      {
      do_command(argv,argc);
//       ppipe(argv,argc);
//        inFile(argv,argc);
/*        if(execvp(argv[0],argv)==-1)
        {
            printf("命令不存在\n");
             exit(1); 
        }
*/
      }
      else
      { 
         waitpid(PID,NULL,0); 
      }
    }
  flag=0;
  argc=0;
 }
  exit(0);
}



int inFile(char* argv[],int argc)//,int infile,int outfile)
{
   int i=0,infile=-1,outfile=-1;

   while(argv[i]){
     if(strcmp(argv[i],"<")==0)
         infile=i;
     if(strcmp(argv[i],">")==0)
         outfile=i;
     i++;
  }
   if(infile>=0)
   {
      if(access(argv[infile+1],F_OK)!=0)
      {
          printf("No such file\n");
          return 0;
      }
   }
    
   pid_t pid=fork();
   if(pid==0)
   {
       if(outfile>=0)
       {
          int fid=open(argv[outfile+1],O_WRONLY|O_CREAT);
          printf("fjk\n");
          close(1);
          dup(fid);
          close(fid);
          argv[outfile]=(char*)0;
//          argv[outfile+1]=NULL;
          execvp(argv[0],argv);
       }
       if(infile>=0)
       {
          int fid2=open(argv[infile+1],O_RDONLY);
          close(0);
          dup(fid2);
          close(fid2);
          argv[infile]=(char*)0;
          execvp(argv[0],argv);
       }
    
 //     execvp(argv[0],argv);
   }

   else
       wait((int*)0);
   

   return 0;
}

int do_command(char* argv[],int& argc)
{
   int i=0,j=0;
   int flag=0;
   char* p;

   if(strcmp(argv[0],"cd")==0)
   {
   int res=0;
   if(argv[1]!=NULL)
   {
      res=chdir(argv[1]);
   }
   else
      printf("Change dir error!\n");
   if(res<0)
      printf("Change dir error\n");

   return 1;
   }

   while(argv[i])
   {
      flag=0;
      p=argv[i];
      if(strcmp(argv[i],"|")==0)
         flag=1;
      if(strcmp(argv[i],">")==0)
         flag=2;
      if(strcmp(argv[i],"<")==0)
         flag=3;
   
//      printf("%d\n",flag);
      if(flag>0)
      {
    
      switch(flag)
      {
        case 3:
        {
           if(access(argv[i+1],F_OK)!=0)
           {
             printf("No such file\n");
             return 0;
           }

            int fid2=open(argv[i+1],O_RDONLY);
            close(0);
            dup(fid2);
            close(fid2);
            argv[i]=(char*)0;
            execvp(argv[0],argv);

          break;
        }
       case 2:
       { 

          int fid=open(argv[i+1],O_WRONLY|O_CREAT);
  //         printf(">>\n");
  
          close(1);
          dup(fid);
          close(fid);
          argv[i]=(char*)0;
          execvp(argv[0],argv);
   
          break;
       }

        case 1:
        { 
          ppipe(argv,argc);
          break;
        }

        default:
          break;
      }
    }
     i++;
   }
        if(execvp(argv[0],argv)==-1)
        {
            printf("命令不存在!\n");
             exit(1);
        }
//    execvp(argv[0],argv);
  return 0;
}



int ppipe(char* argv[],int& argc)
{
   int i=0,j=0;
   char* pt;
   while(argv[i])
   {
      pt=argv[i];
      if(strcmp(argv[i],"|")==0)
      {
          argv[i]='\0';
         

         if(argc==i+1)//huan zhong tiaojian ceshi keyi .the string can't be clr.
         {
            execvp(argv[0],argv);
         }
         
         int pfd[2];
         pipe(pfd);
         int pid1=fork();       //pid_t??
         if(pid1==0)
         {
            close(pfd[0]);
            close(1);
            dup(pfd[1]);
	    close(pfd[1]);
              execvp(argv[0],argv);
         }
         else
         {
            argv[i]=pt;
            waitpid(pid1,NULL,0);
            int m,n;
            for(m=i+1,n=0;argv[m]!='\0';m++,n++)
            {
                strcpy(argv[n],argv[m]);
            }
	   argv[n]='\0';
	//	char ** arg=argv+i+1;
           int  argc1=argc-i-1;
            close(pfd[1]);
            close(0);
            dup(pfd[0]);
	    close(pfd[0]);
            if(argv[0]!=NULL)
            {
                ppipe(argv,argc1);
            }

         }
      }  
      i++;
   }
    execvp(argv[0],argv);
  return 0;
}




int deal_com(char* argv[],int argc,char str[])
{
   int ptr=0;
   int i=0;

  ptr=del_space(ptr,str);
  int outfile=-1;
  int infile=-1;
  int ispipe=-1;

  while(str[ptr]!='\0')
  {
     argv[i]=(char*)malloc(sizeof(char)*30);
     ptr=getone(argv[i],ptr,str);

     if(strcmp(argv[i],">")==0)
        outfile=i;
     else if(strcmp(argv[i],"<")==0)
        infile=i;
     else if(strcmp(argv[i],"|")==0)
        ispipe=i;

     i++;
     argc++;
     ptr=del_space(ptr,str);
   }
   argv[i]='\0';
   return argc;
 }

int del_space(int ptr,char str[])
{
     while(str[ptr]==' ')
        ptr++;
     return ptr;
}

int getone(char* argv1,int ptr,char str[])
{
 //   printf("getone start\n");
     char temp[20];
     int i=0;
     if(str[ptr]=='>'||str[ptr]=='<'||str[ptr]=='|')
     {
        temp[i++]=str[ptr++];
     }
     else
     {
       while((str[ptr]>='a'&&str[ptr]<='z')||(str[ptr]>='A'&&str[ptr]<='Z')
    ||str[ptr]=='_'||str[ptr]=='-'||str[ptr]=='/'||str[ptr]=='.'||(str[ptr]>='0'&&str[ptr]<='9'))
       {
           temp[i++]=str[ptr++];
       }
     }
           temp[i]='\0';
           strcpy(argv1,temp);
           return ptr;
}

int get_com(char str[])
{
  char c;
  int i=0;
  c=getchar();
  while(c!='\n')
  {
    str[i]=c;
    c=getchar();
    i++;
  }
  str[i]='\0';

   return 1;
}

void initial(char arg[COM_COUNT][COM_SIZE],char* argv[])
{
    int s=0,d=0;
//    printf("initial\n");
    for(s;s<COM_COUNT;s++)//每次调用命令之前对参数进行初始化...
    {
        for(d;d<COM_SIZE;d++)
            arg[s][d]='\0';

        argv[s]=NULL;
     }
}

int inCommand(char* str,int& flag)//内部命令
{
  if(strcmp(str,"exit")==0)
  {
      flag=1;
      return 1;
  }
  if(strcmp(str,"logout")==0)
  {
     flag=1;
     return 1;
  }
 
  return 0;
}
/*void cd_com(char* argv[])
{
   int res=0;
   if(argv[1]!=NULL)
   {
      res=chdir(argv[1]);
   }
   else
      printf("Change dir error!\n");
   if(res<0)
      printf("Change dir error\n");

   return;
}*/