ack does not work when run from "grep-find" in Emacs on Windows

Question

I'm trying to use ack-grep as a replacement for grep + find in Emacs on Windows, but ack-grep exits immediately (successfully) without printing any matches. I've tried just about every conceivable combination of command-line parameters to ack-grep, but nothing seems to work.

M-x grep-find

Enter "ack html" to search for files containing "html". Ack exits immediately, printing nothing:

-*- mode: grep; default-directory: "c:/" -*-
Grep started at Tue Feb 23 23:50:52

ack html

Grep finished (matches found) at Tue Feb 23 23:50:52

Executing the same command "ack html" in cmd.exe works fine (showing lots of various files containing the string "html".

Any ideas?

Answer 1

When running ack under Emacs in Windows, I found it sometimes got confused about whether it was supposed to search files or read from STDIN. Here's the function I use to call ack (use M-x ack). You can put this in .emacs.

(defvar ack-command "ack --nogroup --nocolor ")
(defvar ack-history nil)
(defvar ack-host-defaults-alist nil)
(defun ack ()
  "Like grep, but using ack-command as the default"
  (interactive)
  ; Make sure grep has been initialized
  (if (>= emacs-major-version 22)
      (require 'grep)
    (require 'compile))
  ; Close STDIN to keep ack from going into filter mode
  (let ((null-device (format "< %s" null-device))
        (grep-command ack-command)
        (grep-history ack-history)
        (grep-host-defaults-alist ack-host-defaults-alist))
    (call-interactively 'grep)
    (setq ack-history             grep-history
          ack-host-defaults-alist grep-host-defaults-alist)))