/home/myuser/mycapture.txt

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>

// Change this to match the machine's serial port
#define SERDEV "/dev/ttyUSB0"

void initComPort(int* sfd, char* device)
{
  struct termios options;

  *sfd = open(device, O_RDWR | O_NOCTTY | O_NDELAY);
  if (*sfd == -1)
  {
    fprintf(stderr, "unable to open %s\n",device);
    exit(1);
  }
  else
  {
    fcntl(*sfd, F_SETFL, FNDELAY);
  }

  tcgetattr(*sfd, &options);

  cfsetispeed(&options, B115200);
  cfsetospeed(&options, B115200);

  cfmakeraw(&options);

  options.c_cflag &= ~(PARENB | CSTOPB | CSIZE | CRTSCTS);
  options.c_cflag |= (CLOCAL | CREAD | CS8);

  options.c_oflag &= ~OPOST;
  options.c_cc[VMIN] = 1;
  options.c_cc[VTIME] = 0;

  tcsetattr(*sfd, TCSANOW, &options);
}


int main(void)
{
  int sfd;
  FILE *ofd;
  int32_t n, i;
  u_int32_t bytes;
  u_int8_t buff[10000];

  // Initialize the serial port
  initComPort(&sfd, SERDEV);

  while (1)
  {
    // Check if there's any data available to read
    ioctl(sfd, FIONREAD, &bytes);
    if (bytes > 0)
    {
      // Read what we can
      n = read(sfd, buff, 10000);
      if (n < 0)
      {
        fprintf(stderr, "read failed\n");
      }
      if (n > 0)
      {
        ofd = fopen("data.bin", "a");
        if (ofd==NULL)
        {
          fprintf(stderr, "unable to open output file\n");
          exit(2);
        }

        fwrite(buff, 1, n, ofd);

        fclose(ofd);
      }
    }
    usleep(1000);
  }
}