myshell.c

这是一个shell的实现程序。其中System的实现参考了linux的。不好意思哈。

#define _U_D_
#include "myshell.h"





int main(int argc, char* argv[])
{
	char buf[MaxCommandLine];
	int n, paramNumber;
	int commandType;
	char* params[MaxParamNumber];

	Init();


	printPrompt();

	while ((n=read(STDIN_FILENO, buf, MaxCommandLine))>0)
	{
		buf[n]='\0';
//		printf("===========%s\n",buf);
		char * buf2 = buf;
		int j = 0;
		
		for (; 1; j++)
		{
	
			char * buf1;		
			if ((buf1 = strtok(buf2, deline))!=NULL)
			{
				buf2 = buf2 + strlen(buf1) + 1;			
//				printf("===========--%s\n",buf1);	//It needs to operate &.
			
				if( strchr(buf1,'&') )
				{
					ampersandFunc(buf1);
//					printf("++& ampersand.\n");
					continue;					
				}
				

				commandType=parseCommand(buf1, params, &paramNumber);
				switch (commandType)
				{
					case -2:
						printf("illegal command params.\n%s");
						break;
					case -1:
						printf("The command \'%s\' is executed by /bin/shell\n",buf1);
						execute(buf1);
						break;
					case -3:
						break;
					case -4:
						
						break;
					default:	
						commandArray[commandType](params, paramNumber);			
						break;
				}
			}
			else
			{
				break;
			}
			
		}
		
		printPrompt();				

	}
	return 0;
}







//Returned value is -1 which means command beyond the area of myshell.
//-2 means too many parameters.
//-3 means no any inputs from users.
int parseCommand(char* buf, char* params[], int* paramNumber)
{
	int i;
	*paramNumber=0;
	
//	for( i = 0 ; i < strlen(buf) ;i ++)
//	{
//		printf("===========-%X,%c\n",*(buf+i),*(buf+i));
//	}
	

	
	if ((params[*paramNumber]=strtok(buf, delim))!=NULL)
	{
		for (i=CommandNumber-1; i>=0; i--)
		{
			if (strcmp(params[*paramNumber], commandStr[i])==0)
			{
				break;	
			}
		}
		//when not found, i==-1
		if (i==-1)
		{
			return i;
		}
	}
	else
	{
		
		return -3;
	}	
	(*paramNumber)++;
	//the maximum param number is only $(MaxParamNumber), so I test for MaxParamNumber+1 to see if strtok return NULL
	while (1)
	{
		//a continus revoke of strtok() follows the previous revoke's result.
		if ((params[*paramNumber]=strtok(NULL, delim))==NULL)
		{
			break;
		}

		(*paramNumber)++;
		if (*paramNumber==MaxParamNumber)
		{
			//this means the param number is more than MaxParamNumber and it is wrong
			return -2;
		}
	}
	return i;
}


		
void Init()
{
	delim=" \n";
	deline="\n";

	helpStr="Syntax: quit\nSyntax: cd directory\nSyntax: dir [directory]\nSyntax: clr \nSyntax: environ\nSyntax:  echo		\nSyntax: help \nSyntax:  pause\n";


	commandStr[0]="quit";
	commandStr[1]="cd";
	commandStr[2]="dir";
	commandStr[3]="clr";
	commandStr[4]="environ";
	commandStr[5]="echo";
	commandStr[6]="help";
	commandStr[7]="pause";
	commandStr[8]="myshell";

	//A function pointer Array which points the different functions.
	commandArray[0] = quitShell;
	commandArray[1] = changeDir;
	commandArray[2] = listDir;
	commandArray[3] = clrFile;
	commandArray[4] = environFile;
	commandArray[5] = echoFile;
	commandArray[6] = helpFile;
	commandArray[7] = pauseFile;
	commandArray[8] = inputDirect;

	//initialize environment params.			
	InitEnvironParams();
	
	createbatch();

}

//To create batch file when the program is executed.
int createbatch()
{

	FILE * fp= NULL;
	fp = fopen("batch.file","wb");
	char *str = "cd .. \ndir \ncd myshell\necho 1234 567 8956\nhelp > ning.yu\nenviron > yu.ning\n";
	fwrite(str,strlen(str),1,fp);
	fclose(fp);
	return 0;
}