Build the argv list from command line

build_argv.c

int parseline(char *buf, char **argv) {
  char *delim;
  int argc = 0;
  buf[strlen(buf) - 1] = ' ';
  while (*buf && (*buf == ' '))
    buf++;

  while ((delim = strchr(buf, ' '))) {
    argv[argc++] = buf;
    *delim = '\0';
    buf = delim + 1;
    while (*buf && (*buf == ' '))
      buf++;
  }
  argv[argc] = NULL;
  ...
}