#include <stdio.h>
#include <string.h>
#define maxsize 1000

char buffer [maxsize];

void client(int readfd,int writefd)
{
   puts("give pathname:");
   gets(buffer);

   write(writefd,buffer,strlen(buffer));
   //sleep(10);
   while((read(readfd,buffer,strlen(buffer)))>0);
     printf("%s/n",buffer);

}

void server(int readfd,int writefd)
{
   FILE * fp;
   char line[100];
   //sleep(10);
   read(readfd,buffer,strlen(buffer));
   fp=fopen(buffer,"r");
   if(fp==NULL)
   {
       strcpy(buffer,"cannot oepn file");
       write(writefd,buffer,strlen(buffer));
   }
   else
     while(fgets(line,100,fp)!=NULL)
       write(writefd,line,100);
}

int main()
{
    int pipe1[2],pipe2[2];
    int childpid;
    int status;
    pipe(pipe1);
    pipe(pipe2);
    childpid=fork();
    if(childpid>0)
    {
        close(pipe1[0]);
        close(pipe2[1]);
        client(pipe2[0],pipe1[1]);
        wait(&status);
        exit(0);
    }
    else
    {
        close(pipe1[1]);
        close(pipe2[0]);
        server(pipe1[0],pipe2[1]);
        exit(0);
    }

}

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define maxsize 1000

char buffer [maxsize];
void client(int readfd,int writefd)
{
   printf ("give pathname: ");
   fflush (stdout);
   fgets (buffer, sizeof (buffer), stdin);

   write(writefd,buffer, sizeof (buffer));
   while (read(readfd,buffer,sizeof(buffer)) > 0)
        printf("%s",buffer);
}

void server(int readfd,int writefd)
{
   FILE * fp;
   char line[1000];

   read(readfd,buffer,sizeof(buffer));
   if (strchr (buffer, '\n'))
        *strchr(buffer, '\n') = '\0';
   fp=fopen(buffer,"r");
   if(fp==NULL)
   {
       strcpy(buffer,"cannot open file");
       write(writefd,buffer,strlen(buffer));
   }
   else
     while(fgets(line,sizeof(line),fp)!=NULL)
       write(writefd,line,sizeof(line));
}

int main()
{
    int pipe1[2],pipe2[2];
    int childpid;
    int status;
    pipe(pipe1);
    pipe(pipe2);
    childpid=fork();
    if(childpid>0)
    {
        close(pipe1[0]);
        close(pipe2[1]);
        client(pipe2[0],pipe1[1]);
        wait(&status);
        exit(0);
    }
    else
    {
        close(pipe1[1]);
        close(pipe2[0]);
        server(pipe1[0],pipe2[1]);
        exit(0);
    }

}

//implementation of cat <filename> | wc -l

#include <stdio.h>
#include <string.h>
#define size 500
int main(int argc,char * argv[])
{

   int pipe1[2];
   int childpid;
   FILE * fp;
   char buffer[size];
   int status;
   int lines;
   if(argc!=2)
   {
     printf("usage : mycat <file name>\n");
     exit(1);
   }
   pipe(pipe1);
   childpid=fork();
   if(childpid>0)
   {
      close(pipe1[0]);
      fp=fopen(argv[1],"r");
      if(fp==NULL)
      {
         printf("Cannot open file");
         exit(1);
      }
     while(fgets(buffer,sizeof(buffer),fp)!=NULL)
       write(pipe1[1],buffer,strlen(buffer));

      fclose(fp);
      wait(&status);
      close(pipe1[1]);
      exit(0);
   }
   else
   {
      close(pipe1[1]);
      lines=0;
       while (read(pipe1[0],buffer,sizeof(buffer)) > 0)
           lines++;
      printf("%d",lines);
      close(pipe1[0]);
      exit(0);
   }
}