#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <string.h>

#define LINELENGTH 132

int main(int argc, char *argv[])
{
   long r, line = 0, lines = 0;
   FILE *cfile;
   char *buffer = (char *) malloc(LINELENGTH);

   if (argc > 1)
   { 
       if (!(cfile = fopen(argv[1], "r"))) 
       {
          printf("%s: Couldn't open file, \"%s\".\n", argv[0], argv[1]);
          exit(3);
       }
   }
   else if (!(cfile = fopen("s:random-sequences", "r"))) 
   {
      printf("%s: Couldn't open file, \"s:random-sequences\".\n", argv[0]);
      exit(3);
   }

   while (fgets(buffer, LINELENGTH, cfile) != NULL) lines++;

   srand(time(NULL));

   r = rand() % lines;

   fseek(cfile, 0, SEEK_SET);

   while (fgets(buffer, LINELENGTH, cfile) != NULL)
   {
      if (line++ >= r && strlen(buffer) < LINELENGTH)
      {
         system(buffer);
         break;
      }
   }

   fclose(cfile);
   free(buffer);
}