strip_escapes
char *strip_escapes(char *);
fp = (*fn == '!') ? popen(fn+1, "w") : fopen(strip_escapes(fn), mode);
fp = (*fn == '!') ? popen(fn + 1, "r") : fopen(strip_escapes(fn), "r");
printf("%s\n", strip_escapes(old_filename));
j = strlen(s = strip_escapes(old_filename));