shell.c

linux 下模拟shell的实现。 支持管道等功能。读proc文件

#include <unistd.h>
#include <stdio.h>
#define MAX_CMD 100
int main()
{
	int pid,ppid;
	int i,j,jj,kk,k,len,tag,ptag,pipetag;
	char cmd[10][10];
	char pcmd[10][10];
	char *pargv[10]={NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL};
	char *argv[10]={NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL};
	char buffer[100];
	char *file,*pfile;
	char* tip="kxz_shell# ";
	int fds[2];
	char pipebuf[12]={'\0','\0','\0','\0','\0','\0','\0','\0','\0','\0','\0','\0'};
	printf("\nWelcome to kxz_shell!\nDeveloped by Kong Xiangzhen 03055078 jsj33\n\n ");
again:
	pipetag=0;
        for(i=0;i<10;i++)
	{
		argv[i]=NULL;
	}
	
	if((len=write(1,tip,11))<0)
	{
		perror("write error!");
		exit(0);
	}

	if((len=read(0,buffer,sizeof(buffer)))<0)
	{
		perror("read error!");
		exit(0);
	}
	i=0;
	j=0;
	jj=0;
        k=0;
	kk=0;
        while(i<len-1)
	{
		
	        while((buffer[i]!=' '&&buffer[i]!='|')&&i<len-1)
	        {
	         	cmd[j][k]=buffer[i];
	        	i++;
			k++;
         	}
		cmd[j][k]='\0';
        	argv[j]=cmd[j];
		printf("cmd %d=%s**\n",j,cmd);
		if(buffer[i]==' ')
		{
			while(buffer[i]==' ')
				i++;
			k=0;
			j++;
			
		}
		if(buffer[i]=='|')
        	{
			pipetag=1;
			i++;
			while(buffer[i]==' ')i++;
			while(buffer[i]!=' '&&i<len-1)
			{
				pcmd[jj][kk]=buffer[i];
				i++;
				kk++;
			}
			pcmd[jj][kk]='\0';
			pargv[jj]=pcmd[jj];
			
			printf("pcmd %d=%s**\n",jj,pcmd);
		}
	}
         
	while((pid=fork())<0);
	if(pid==0)
	{
		printf("pipetag=%d\n",pipetag);
		if(pipetag==1)
		{
			if(pipe(fds)==-1)
			{
				perror("Pipe Error");
				exit(-1);
			}
			while((ppid=fork())<0);
			if(ppid>0)
			{
				close(fds[0]);
				write(fds[1],"/dev/stdout",11);
				sleep(3);
	                	file=cmd[0];
	                	tag=execvp(file,argv);
				wait(NULL);
			}
			else{
				close(fds[1]);
				read(fds[0],pipebuf,11);
				printf("recive =%s***\n",pipebuf);
				pargv[1]=pipebuf;
				
				printf("\nThis is out by pipe\n");
				pfile=pcmd[0];
				ptag=execvp(pfile,pargv);
				if(ptag<0)
					printf("Bad command for pipe!\n");
			}
		}
                            
	       	file=cmd[0];
	             	tag=execvp(file,argv);
		if(tag<0)
			printf("Bad command!\n");
				
				
	}
	else{
		wait(0);
		goto again;
	}
	
	return 0;
}