problem with piping in my own implementation of shell
- by codemax
Hey guys,
i am implementing my own shell.
I want to involve piping. i searched here and i got a code. But it is not working.Can any one help me?
this is my code
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ipc.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <iostream>
#include <cstdlib>
using namespace std;
char temp1[81][81],temp2[81][81] ,*cmdptr1[40], *cmdptr2[40];
void process(char**,int);
int arg_count, count;
int arg_cnt[2];
int pip,tok;
char input[81];
int fds[2];
void process( char* cmd[])//, int arg_count )
{
pid_t pid;
pid = fork();
//char path[81];
//getcwd(path,81);
//strcat(path,"/");
//strcat(path,cmd[0]);
if(pid < 0)
{
cout << "Fork Failed" << endl;
exit(-1);
}
else if( pid == 0 )
{
execvp( cmd[0] , cmd );
}
else
{
wait(NULL);
}
}
void pipe(char **cmd1, char**cmd2)
{
cout<<endl<<endl<<"in pipe"<<endl;
for(int i=0 ; i<arg_cnt[0] ; i++)
{
cout<<cmdptr1[i]<<" ";
}
cout<<endl;
for(int i=0 ; i<arg_cnt[1] ; i++)
{
cout<<cmdptr2[i]<<" ";
}
pipe(fds);
if (fork() == 0 ) {
dup2(fds[1], 1);
close(fds[0]);
close(fds[1]);
process(cmd1);
}
if (fork() == 0) {
dup2(fds[0], 0);
close(fds[0]);
close(fds[1]);
process(cmd2);
}
close(fds[0]);
close(fds[1]);
wait(NULL);
}
void pipecommand(char** cmd1, char** cmd2)
{
cout<<endl<<endl;
for(int i=0 ; i<arg_cnt[0] ; i++)
{
cout<<cmd1[i]<<" ";
}
cout<<endl;
for(int i=0 ; i<arg_cnt[1] ; i++)
{
cout<<cmd2[i]<<" ";
}
int fds[2]; // file descriptors
pipe(fds);
// child process #1
if (fork() == 0)
{
// Reassign stdin to fds[0] end of pipe.
dup2(fds[0], STDIN_FILENO);
close(fds[1]);
close(fds[0]);
process(cmd2);
// child process #2
if (fork() == 0)
{
// Reassign stdout to fds[1] end of pipe.
dup2(fds[1], STDOUT_FILENO);
close(fds[0]);
close(fds[1]);
// Execute the first command.
process(cmd1);
}
wait(NULL);
}
close(fds[1]);
close(fds[0]);
wait(NULL);
}
void splitcommand1()
{
tok++;
int k,done=0,no=0;
arg_count = 0;
for(int i=count ; input[i] != '\0' ; i++)
{
k=0;
while(1)
{
count++;
if(input[i] == ' ')
{
break;
}
if((input[i] == '\0'))
{
done = 1;
break;
}
if(input[i] == '|')
{
pip = 1;
done = 1;
break;
}
temp1[arg_count][k++] = input[i++];
}
temp1[arg_count][k++] = '\0';
arg_count++;
if(done == 1)
{
break;
}
}
for(int i=0 ; i<arg_count ; i++)
{
cmdptr1[i] = temp1[i];
}
arg_cnt[tok] = arg_count;
}
void splitcommand2()
{
tok++;
cout<<"count is :"<<count<<endl;
int k,done=0,no=0;
arg_count = 0;
for(int i=count ; input[i] != '\0' ; i++)
{
k=0;
while(1)
{
count++;
if(input[i] == ' ')
{
break;
}
if((input[i] == '\0'))
{
done = 1;
break;
}
if(input[i] == '|')
{
pip = 1;
done = 1;
cout<<"PIP";
break;
}
temp2[arg_count][k++] = input[i++];
}
temp2[arg_count][k++] = '\0';
arg_count++;
if(done == 1)
{
break;
}
}
for(int i=0 ; i<arg_count ; i++)
{
cmdptr2[i] = temp2[i];
}
arg_cnt[tok] = arg_count;
}
int main()
{
cout<<endl<<endl<<"Welcome to unique shell !!!!!!!!!!!"<<endl;
tok=-1;
while(1)
{
cout<<endl<<"***********UNIQUE**********"<<endl;
cin.getline(input,81);
count = 0,pip=0;
splitcommand1();
if(pip == 1)
{
count++;
splitcommand2();
}
cout<<endl<<endl;
if(strcmp(cmdptr1[0], "exit") == 0 )
{
cout<<endl<<"EXITING UNIQUE SHELL"<<endl;
exit(0);
}
//cout<<endl<<"Arg count is :"<<arg_count<<endl;
if(pip == 1)
{
cout<<endl<<endl<<"in main :";
for(int i=0 ; i<arg_cnt[0] ; i++)
{
cout<<cmdptr1[i]<<" ";
}
cout<<endl;
for(int i=0 ; i<arg_cnt[1] ; i++)
{
cout<<cmdptr2[i]<<" ";
}
pipe(cmdptr1, cmdptr2);
}
else
{
process (cmdptr1);//,arg_count);
}
}
}
I know it is not well coded. But try to help me :(
