Babel

Every now and then i need to translate a word or a phrase, and switching to emacs-w3m to use one of the on-line translation services is a bit of a chore. Thanks to Juergen Hoetzel’s babel, life is easier now.

Keeping your secrets secret

As much as i try to avoid it, i always end up with lots of usernames and passwords to remember, not to mention a couple of bank accounts and a credit card number for on-line shopping. There’s no way i’m going to remember any of them—why, i even need to keep track of my telephone number. Time to write down a tidy nice little list, that is, time to look for and set up an adequate emacs mode or two.

When it comes to keeping lists, the table editor of org-mode is what you need. Org-mode is included in emacs 22, but Carsten &co. keep adding new stuff and fixing bugs, so it won’t hurt you to get the unstable version from its website. It comes with a nice manual and installing it is a freeze. You enter table mode by typing a vertical bar (|) to separate columns:

  * Bank accounts
    |Account | Credit card | Expiry date | Password |
    |-

From there TAB and RET are your friends: new rows are created and column widths adjusted automagically. You can also add separators by starting a line with |- (as i did above) and typing TAB. In no time you’ll have something like this:

* Banks

  |-----------------+------------------+----------|
  | Account         | Credit card      | password |
  |-----------------+------------------+----------|
  | The credit box  | 8180819999999333 | fooo     |
  | GNU Free Credit | 6969696969696969 | boobarp  |
  | Engineering Safe| 0000000111111111 | passwdd  |
  | paypal          |                  | paaassss |
  |-----------------+------------------+----------|

* Sites

  |-------------------------------+------------------------+
  | site                          | user        | password |
  |-------------------------------+------------------------+
  | http://www.gnu.org            | a user name | password |
  | http://journals.foo.org       | a user name | password |
  | http://philosophy.org         | a user name | password |
  | http://linkedin.com           | a user name | password |
  | http://www.pragpro.com        | a user name | password |
  | http://www.tug.org/members    | a user name | password |
  |-------------------------------+------------------------+

* Source code repositories...

All in conveniently foldable sections, so that you can expand only the interesting section.

But, of course, you don’t want to save this as a regular file (let alone publish it on the internet). Even on a Unix machine, protecting it via file permissions is very weak. Nah, what you want is to encrypt the thing. To that end, one can use public key cryptography.

In a nutshell, you generate a pair of keys: one of them is private, only for your eyes, and therefore should be protected by a solid password; the other one is public: you make it available to anyone that wants to communicate with you. People then write their secret text and encrypt it using the public key. When that’s done, only your secret key (barring the NSA) can decipher the text. Of course, nothing prevents you from using the same device to encrypt and decrypt your passwords file.

This being an emacs blog, i won’t delve into the details of using GnuPG to create a key pair if you don’t already have it. But you being an emacs user, i’m sure you’ll be quite able to run gpg --key-gen to generate your keys.

You could now use gpg to manually cipher and decipher the passwords file, but, you know, one uses emacs because it can do almost any thing for you. In this case, EasyPG will take care of the chore of decrypting the file every time you open it and encrypting it back when it goes to disk. The EasyPG package comes bundled with emacs 23, and, again, it is very easy to install if you are using previous emacs versions. This is the configuration i use for this package:

;; Emacs 23: bundled EasyPG
(require 'epa)
(epa-file-enable)

or, if you installed it externally:

;; EasyPG installed in path/to/epg
(add-to-list 'load-path "path/to/epg")
(require 'epa-setup)
(epa-file-enable)

(Yeah, it’s called easy for a reason!) With this magic incantation in place, every time you open a file with the extension .gpg, EasyPG will do the work for you.

So, all that is left to do is to save our file as, say, dobeedoo.gpg and inform emacs that we want to open it as an org-mode file by adding the following first line to it:

-*- mode: org -*- -*- epa-file-encrypt-to: ("my_key_email@foo.org") -*-

As you can see, we’re also telling EasyPG what key it should use for its cryptographic activities.

That’s it. No rocket science here, but very handy nonetheless, and a very nice example of how different major (org) and minor (org-table, epa) emacs modes can work together for you. A perfect use case of minor modes providing functionality orthogonal to that in the major mode, which is caring about the actual file contents. Personally, this is also the use case that got me started with org-mode: may it enlighten you too

Happy encrypting!

(BTW, now that you have EasyPG installed, try M-x epa-list-keys, a nice keyring browser, if you ask me.)

Org from the horse’s mouth

After many years using Muse for organising my notes, some moths ago i finally moved to Org for all my planning and note taking. I have some posts in the pipeline with some tricks i used, but i cannot think of a better way to get started than this recent talk by Carsten Dominik, the creator of Org himself:

Enjoy!

Two Gnus tricks

I’ve added a couple of tweaks to my Gnus config lately. Nothing earth-shattering, but in both cases i was writing my own elisp for something that was already in there. So, i’ve thought i’d share them and, maybe, save you the trouble.

The first one is a quickie, and you probably know about it; but for some reason it took me ages to discover the correct configuration knob. When you reply a mail, emacs will use the value of user-mail-address to compose the From: header. One can also tweak gnus-posting-styles to change the address on a per group basis. But what i really wanted was to use the address in the mail i was replying to. I was writing a hook to that effect when i found the variable to set to accomplish it: message-alternative-mails. Here’s how i set it up:

    (setq message-alternative-emails
        (regexp-opt '("jao@gnu.org" "jaortega@goodmail.com" "jao@member.fsf.org")))

Worked like a charm. Now for the second one.

As i’ve mentioned in some post before, Gnus let’s you customise the summary line to your heart’s content by tweaking the variable gnus-summary-line-format. I normally use emacs in a maximized urxvt terminal, so i’ve got plenty of room in my summary lines. One thing i wanted to add is the message’s date in a) my time zone and b) human readable form (you know, something like ‘Today, 22:33′ or ‘Yesterday, 02:44′). I only knew two format directives showing a date (%d and %D), but neither fulfilled my wishes. So i started coding my own, but halfway discovered that Gnus already comes with a custom one, called user-date. You use it by inserting %&user-date; in the line format string. It works in conjunction with a configuration stored in gnus-user-date-format-alist, which contains a lists of pairs. The first member of the pair is the age of the message, the second a time format string for displaying the date of messages that old. You’ll understand it better with an example, taken from my current configuration:

    (setq gnus-user-date-format-alist
          '(((gnus-seconds-today) . "Today, %H:%M")
            ((+ 86400 (gnus-seconds-today)) . "Yesterday, %H:%M")
            (604800 . "%A %H:%M") ;;that's one week
            ((gnus-seconds-month) . "%A %d")
            ((gnus-seconds-year) . "%B %d")
            (t . "%B %d '%y"))) ;;this one is used when no other does match

    (setq gnus-summary-line-format
      (concat "%U%R %~(pad-right 2)t%* %uj %B%~(max-right 30)~(pad-right 30)n  "
              "%~(max-right 90)~(pad-right 90)s %-135=%&user-date;\n"))

I’ve copied my whole line format so that you can see, in addition, how i manage to keep things aligned in a frame around 180 columns wide. For details on the %uj directive, see this previous post.

Numbered links in emacs-w3m

I’ve been trying conkeror as my secondary browser for a while, and i really like it. It has a much smaller memory footprint than Firefox, and it doesn’t take ages to start up. It’s also nicely hackable and extensible (using javascript), and it comes with some interesting functionality, available out of the box. For instance, external editor support or link numbering: pressing ‘f’ numbers all links in the page and you enter a link number to follow it.

As it happens, recent (as in CVS 1.4.4) versions of emacs-w3m offer a similar functionality in the w3m-lnum package. M-x w3m-link-numbering-mode toggles a minor mode showing link numbers on an overlay, and M-n M-x w3m-move-numbered-anchor, where n is the link number, moves the pointer to the desired link. Providing conkeror’s
more handy functionality is then a matter of a few elisp lines:

 
  (require 'w3m-lnum)
  (defun jao-w3m-go-to-linknum ()
    "Turn on link numbers and ask for one to go to."
    (interactive)
    (let ((active w3m-link-numbering-mode))
      (when (not active) (w3m-link-numbering-mode))
      (unwind-protect
          (w3m-move-numbered-anchor (read-number "Anchor number: "))
        (when (not active) (w3m-link-numbering-mode)))))

  (define-key w3m-mode-map "f" 'jao-w3m-go-to-linknum)

Happy browsing!

Map of Emacs Users

Add yourself to the Map of Emacs Users around the world… and leave a note with the emacsen version(s) you use, just for the fun of it! You can also take a look at Emacs google trends (or the Emacs vs. that other editor one), the EmacsUserLocations page or this Emacs Screenshots flickr group.

Gmail envy

Although Gnus is my primary mail reader, there’s lots of things i like about Gmail (actually, Gmail is my primary inbox: Gnus reads mail from there). For instance, a little feature i love in Gmail is those markers that tell you whether you’re one of the direct recipients of a mail. When seeing a long list of mails in a mail list, i can quickly identify those with me explicitly in the To: or Cc: headers: chances are i’m slightly more interested in them.

In Gnus, one can customize the information shown in the message list by tweaking the variable gnus-summary-line-format. If you press C-h v gnus-summary-line-format to see all the formatting options, you’ll see there’s a lot of information to be shown, but not the one we want. But, as is always the case, we have a hook to extend the format to our hearts content: the %uX directive, where X is any letter you want. When Gnus sees that directive, it calls gnus-user-format-function-X, a function you must write returning a string that gets inserted in the summary line. So here we go: first i define a string with a regexp of my email addresses:

(defvar *jao-mails*
        "jao@foo\\.org\\|jao@baz\\.com\\|jao@grogle\\.com")

and then i function which returns a “»” if i’m the only recipient of the message, or a “~” if i’m in the To:, Cc: or BCc: headers among others:

(defun gnus-user-format-function-j (headers)
  (let ((to (gnus-extra-header 'To headers)))
    (if (string-match *jao-mails* to)
        (if (string-match "," to) "~" "»")
        (if (or (string-match *jao-mails*
                              (gnus-extra-header 'Cc headers))
                (string-match *jao-mails*
                              (gnus-extra-header 'BCc headers)))
            "~"
            " "))))

Then all that is left is using it in my gnus-summary-line-format:

(setq
 gnus-summary-line-format
 "%U%R %~(pad-right 2)t%* %uj %B%~(max-right 20)~(pad-right 20)n %s\n")

Notice the %uj doing the trick here. I’m sure you’ll come up with other uses to this extension mechanism, which, by the way, is also available for gnus-group-line-format, the variable governing how lines in the *Group* buffer are displayed.

Smooth scrolling

A quick and sweet tip for one of those things surprisingly difficult to get right in emacs: buffer scrolling. If you find awkward the way emacs makes your buffers jump when you move the cursor near their begin or end, try putting this file in your load path and (require 'smooth-scrolling). You can control when scrolling starts by setting the variable smooth-scroll-margin: when the cursor is that far from the top or bottom borders, scrolling begins (default is 10 lines). Works like a charm here.

By the way, as Adam (the author of the code above) points out in the comments below, the problem is trickier than it seems. If you’re curious, this EmacsWiki page gives the details.

Quick keybindings

So, you just executed a complex, wonderful emacs command using the minibuffer and you’re so excited that need to immediately write it down, lest you forget. As you may already know, you don’t need pen and paper for that. Emacs will do it for you: just press C-x ESC ESC (that is, repeat-complex-command) and you’ll see an Elisp form in your minibuffer that reproduces your last command (C-h w C-x ESC ESC for more details). Now C-a C-k and you got it in the kill-ring, ready to be yanked in one of your configuration files.

I don’t use this trick that much because over the years more and more emacs automatisms are recorded either in my nervous system or my config files. Except for one thing: defining keybindings. There’re a bunch of ways to define a keybinding in emacs, and i’m never sure what’s the right one when there’re special keys involved. The solution is to define the key interactively with M-x global-set-key. Once i’m done, i play C-x ESC ESC and presto: an elisp snippet to yank in my .emacs appears in the minibuffer.

Happy binding!

Gnus and Google Groups

Eternal September notwithstanding, i have great daily fun reading a bunch of usenet groups, and their articles are sometimes a source of ideas for blogging. Of course, my usenet client is Gnus; but in a blog post one needs the Google Groups URL when mentioning and article. So, i just spent five minutes writing a snippet to go from Gnus to GG in a keystroke:

(defun jao-gnus-goto-google ()
  (interactive)
  (when (memq major-mode '(gnus-summary-mode gnus-article-mode))
    (when (eq major-mode 'gnus-article-mode)
      (gnus-article-show-summary))
    (let* ((article (gnus-summary-article-number))
           (header (gnus-summary-article-header article))
           (id (substring (mail-header-id header) 1 -1)))
      (browse-url
       (format "http://groups.google.com/groups?selm=%s" id)))))

As you see, i just check that i’m viewing a post, obtain the message identifier (trimming surrounding markup) and construct a query that looks up the corresponding GG article.

Talk about extensibility.