GNU Emacs Manual - Emergency Escape

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### Emergency Escape

Because at times there have been bugs causing Emacs to loop without checking `quit-flag`, a special feature causes Emacs to be suspended immediately if you type a second `C-g` while the flag is already set, so you can always get out of GNU Emacs. Normally Emacs recognizes and clears `quit-flag` (and quits!) quickly enough to prevent this from happening. (On MS-DOS and compatible systems, type `C-`BREAK`` twice.)

When you resume Emacs after a suspension caused by multiple `C-g`, it asks two questions before going back to what it had been doing:

    Auto-save? (y or n)
    Abort (and dump core)? (y or n)

Answer each one with `y` or `n` followed by `RET`.

Saying `y` to ``Auto-save?'` causes immediate auto-saving of all modified buffers in which auto-saving is enabled.

Saying `y` to ``Abort (and dump core)?'` causes an illegal instruction to be executed, dumping core. This is to enable a wizard to figure out why Emacs was failing to quit in the first place. Execution does not continue after a core dump. If you answer `n`, execution does continue. With luck, GNU Emacs will ultimately check `quit-flag` and quit normally. If not, and you type another `C-g`, it is suspended again.

If Emacs is not really hung, just slow, you may invoke the double `C-g` feature without really meaning to. Then just resume and answer `n` to both questions, and you will arrive at your former state. Presumably the quit you requested will happen soon.

The double-`C-g` feature is turned off when Emacs is running under the X Window System, since you can use the window manager to kill Emacs or to create another window and run another program.

On MS-DOS and compatible systems, the emergency escape feature is sometimes unavailable, even if you press `C-`BREAK`` twice, when some system call (MS-DOS or BIOS) hangs, or when Emacs is stuck in a very tight endless loop (in C code, not in Lisp code).

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