// to compile:  $gcc -o bpsPlot bpsPlot.c 
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <signal.h>

int numSamples = 60;

static void sig_alarm(int signo) {        /* argument is signal number */
    return;
}

int main(int argc, char* argv[]) {
    int i;
    FILE *pf;
    char cmd[256];
    char junk[64];
    long totalTxBytes_i, totalTXBytes_i_1;
    
    struct itimerval timerval;
    struct timeval period;
    int signo;
    FILE * outData;

    period.tv_sec=1;
    period.tv_usec=0;
    timerval.it_interval=timerval.it_value=period;
    setitimer(ITIMER_REAL, & timerval, NULL);
    signal(SIGALRM, sig_alarm);
    
    sprintf(cmd, "ifconfig %s | grep \"TX packets\" ", argv[1]); 
    outData = fopen("outData.txt", "w");

    for (i=-1; i <numSamples; i++) { 
        pause();
        pf = popen(cmd, "r");
        fscanf(pf, "%s %s %s %s %ld", junk, junk, junk, junk, &totalTxBytes_i);
        pclose(pf);
        if (i>=0)
            fprintf(outData, "%i %i\n", i,8*(totalTxBytes_i - totalTXBytes_i_1));
        totalTXBytes_i_1 = totalTxBytes_i;
    }
    period.tv_sec=0;
    timerval.it_interval=timerval.it_value=period;
    setitimer(ITIMER_REAL, & timerval, NULL);  //stop timer
    fflush(outData);
    close(outData);
    pf = popen("gnuplot", "w");
    fprintf(pf, "plot \"%s\" using 1:2 with lines lt 1\n", "outData.txt");
    fprintf(pf, "pause -1 \n"); fflush(pf);
    sleep(5);
    fprintf(pf, "\n exit"); fflush(pf);
    pclose(pf);
    exit(0);
}