limit lines to screen width

src/main.c

@@ -42,7 +42,14 @@ void read_show_output(FILE *s, size_t *shown, size_t *total) {
  if (read < 0)
  break;
  if (*shown < LINES - 2) {
- fputs(line, stdout); // TODO: truncate long lines
+ // sometimes newline, sometimes not, so chomp off any newline and
+ // we'll add it ourselves for consistency.
+ if (line[read-1] == '\n')
+ read -= 1;
+ // truncate lines that are wider than the screen.
+ if (read > COLS)
+ read = COLS;
+ printf("%.*s\n", (int)read, line);
  *shown += 1;
  }
  *total += 1;