Termios transmitting user name before data - serial-port

Question

I am trying to use serial communication in Raspberry Pi. I found this link. I made only one change in the code and increase the buffer value to 30. Here my edited code:-
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
int main(int argc, char* argv[]) {
struct termios serial;
char* str = "Hello";
char buffer[30];
if (argc == 1) {
printf("Usage: %s [device]\n\n", argv[0]);
return -1;
}
printf("Opening %s\n", argv[1]);
int fd = open(argv[1], O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1) {
perror(argv[1]);
return -1;
}
if (tcgetattr(fd, &serial) < 0) {
perror("Getting configuration");
return -1;
}
// Set up Serial Configuration
serial.c_iflag = 0;
serial.c_iflag = 0;
serial.c_oflag = 0;
serial.c_lflag = 0;
serial.c_cflag = 0;
serial.c_cc[VMIN] = 0;
serial.c_cc[VTIME] = 0;
serial.c_cflag = B115200 | CS8 | CREAD;
tcsetattr(fd, TCSANOW, &serial); // Apply configuration
// Attempt to send and receive
printf("Sending: %s\n", str);
//int wcount = write(fd, &str, strlen(str));
int wcount = write(fd, str, strlen(str));
if (wcount < 0) {
perror("Write");
return -1;
}
else {
printf("Sent %d characters\n", wcount);
}
// int rcount = read(fd, &buffer, sizeof(buffer));
int rcount = read(fd, buffer, sizeof(buffer));
if (rcount < 0) {
perror("Read");
return -1;
}
else {
printf("Received %d characters\n", rcount);
}
buffer[rcount] = '\0';
printf("Received: %s\n", buffer);
close(fd);
}
I short Rx and Tx pin and run this code. I should receive "Hello" but I am getting this:-
Received: pi#raspberrypi:~$ Hello
So, it is clear that I am receiving "Hello" but additionally I am automatically transmitting
pi#raspberrypi:~$
So, please tell me I to stop transmitting my user name.