The "#pragma" command is specified in the ANSI standard to have an arbitrary implementation-
defined effect. In the GNU C preprocessor, "#pragma" first attempts to run the game "rogue"; if that
fails, it tries to run the game "hack"; if that fails, it tries to run GNU Emacs displaying the Tower of
Hanoi; if that fails, it reports a fatal error. In any case, preprocessing does not continue.

—Manual for version 1.34 of the GNU C compiler

And the corresponding source code in the preprocessor part of the compiler was:

/*

* the behavior of the #pragma directive is implementation

defined.

* this implementation defines it as follows.

*/

do_pragma ()

{

close (0);

if (open ("/dev/tty", O_RDONLY, 0666) != 0)

goto nope;

close (1);

if (open ("/dev/tty", O_WRONLY, 0666) != 1)

goto nope;

execl ("/usr/games/hack", "#pragma", 0);

execl ("/usr/games/rogue", "#pragma", 0);

execl ("/usr/new/emacs", "-f", "hanoi", "9", "-kill", 0);

execl ("/usr/local/emacs", "-f", "hanoi", "9", "-kill", 0);

nope:

fatal ("You are in a maze of twisty compiler features, all

different");

}

Especially droll is the fact that the description in the user manual is wrong, in that the code shows that
"hack" is tried before "rogue".

Chapter 2. It's Not a Bug, It's a Language Feature

Bugs are by far the largest and most successful class of entity, with nearly a million known species. In
this respect they outnumber all the other known creatures about four to one.

—Professor Snopes' Encyclopedia of Animal Life

why language features matter...sins of commission: switches let you down with fall
through...available hardware is a crayon?...too much default visibility...sins of mission: overloading
the camel's back..."some of the operators have the wrong precedence"...the early bug gets() the
Internet worm...sins of omission: mail won't go to users with an "f" in their user name...space–the
final frontier...the compiler date is corrupted...lint should never have been separated out...some light
relief—some features really are bugs