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Bzip2 mini-HOWTO: Using bzip2 with emacs Next Previous Contents

6. Using bzip2 with emacs

6.1 Changing emacs for everyone:

I've written the following patch to jka-compr.el which adds bzip2 to auto-compression-mode.

Disclaimer: I have only tested this with emacs-20.2, but have no reason to believe that a similar approach won't work with other versions.

To use it,

  1. Go to the emacs-20.2/lisp source directory (wherever you untarred it)
  2. Put the patch below in a file called jka-compr.el.diff (it should be alone in that file ;).
  3. Do
     patch < jka-compr.el.diff
  4. Start emacs, and do
     M-x byte-compile-file jka-compr.el
  5. Leave emacs.
  6. Move your original jka-compr.elc to a safe place in case of bugs.
  7. Replace it with the new jka-compr.elc.
  8. Have fun!
--- jka-compr.el        Sat Jul 26 17:02:39 1997
+++ jka-compr.el.new    Thu Feb  5 17:44:35 1998
@@ -44,7 +44,7 @@
 ;; The variable, jka-compr-compression-info-list can be used to
 ;; customize jka-compr to work with other compression programs.
 ;; The default value of this variable allows jka-compr to work with
-;; Unix compress and gzip.
+;; Unix compress and gzip.  David Fetter added bzip2 support :)
 ;; If you are concerned about the stderr output of gzip and other
 ;; compression/decompression programs showing up in your buffers, you
@@ -121,7 +121,9 @@
 ;;; I have this defined so that .Z files are assumed to be in unix
-;;; compress format; and .gz files, in gzip format.
+;;; compress format; and .gz files, in gzip format, and .bz2 files,
+;;; in the snappy new bzip2 format from http://www.muraroa.demon.co.uk.
+;;; Keep up the good work, people!
 (defcustom jka-compr-compression-info-list
   ;; compr-message  compr-prog  compr-args
@@ -131,6 +133,10 @@
      "compressing"    "compress"     ("-c")
      "uncompressing"  "uncompress"   ("-c")
      nil t]
+    ["\\.bz2\\'"
+     "bzip2ing"        "bzip2"         ("")
+     "bunzip2ing"      "bzip2"         ("-d")
+     nil t]
      "zipping"        "gzip"         ("-c" "-q")
      "unzipping"      "gzip"         ("-c" "-q" "-d")

6.2 Changing emacs for one person:

Thanks for this one go to Ulrik Dickow, ukd@kampsax.dk, Systems Programmer at Kampsax Technology:

To make it so you can use bzip2 automatically when you aren't the sysadmin, just add the following to your .emacs file.

;; Automatic (un)compression on loading/saving files (gzip(1) and similar)
;; We start it in the off state, so that bzip2(1) support can be added.
;; Code thrown together by Ulrik Dickow for ~/.emacs with Emacs 19.34.
;; Should work with many older and newer Emacsen too.  No warranty though.
(if (fboundp 'auto-compression-mode) ; Emacs 19.30+
    (auto-compression-mode 0)
  (require 'jka-compr)
  (toggle-auto-compression 0))
;; Now add bzip2 support and turn auto compression back on.
(add-to-list 'jka-compr-compression-info-list
              "zipping"        "bzip2"         ()
              "unzipping"      "bzip2"         ("-d")
              nil t])
(toggle-auto-compression 1 t)

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