Programming

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

int main( void )
{
        char buf[20];

        while( 1 )
        {
                       read(STDIN_FILENO , buf ,  sizeof( buf ));
                       write(STDOUT_FILENO, buf , strlen( buf ));

                if(!strcmp(buf,"q\n"))
                        break;
        }

        return 0;
}

size_t bytes_read;
   .
   .
   .
bytes_read = read( STDIN_FILENO, buf, sizeof( buf ) - 1 );
if ( bytes_read >= 0 )
{
    buf[ bytes_read ] = '\0';
}
   .
   .
   .

      1 #include<unistd.h>
      2 #include<fcntl.h>
      3 int main( void )
      4 {
      5         int fd, fd1;
      6         fd = open("MyFile.txt",O_RDWR|O_CREAT);
      7         close(1);
      8         if( ( fd1 = dup(fd))!= 1)
      9                 printf("Its not set \n");
     10         printf("fd1 = %d \n", fd1);
     11         close(fd);
     12         printf("hello");// this will be printed in MyFile.txt .
     13         return 0;
     14 }

#include <unistd.h>
#include <fcntl.h>
// Need this for printf
#include <stdio.h>

int main( void )
{
        int fd = open("MyFile.txt",O_RDWR|O_CREAT, 0666);

        if(fd < 0)
        {
                perror("Couldn't open MyFile.txt");
                return(1);
        }

        if(dup2(fd, STDOUT_FILENO) < 0)
        {
                perror("Couldn't duplicate file");
                return(1);
        }

        close(fd);

        printf("hello");// this will be printed in MyFile.txt .
        return 0;
}