Tag Archives: How-Tos

How to use Locate from Emacs on Windows

If you are like me, you like to:

  • Live in Emacs as much as possible to avoid context-switching
  • Set up Emacs so your environment abstracts the OS as much as possible

Being able to sit down at any of my computers and type M-x locate in Emacs is a requirement for me, even if It’s running Windows underneath.

In this post I’ll describe how to set up a locate(1) command on Windows 10, and how to access it from Emacs.

Step 1. Install Locate32

Download and install locate32 on your machine. It doesn’t have an installer, it just gives you a directory full of things, including the locate.exe binary. I put mine in "C:/Users/rml/Programs/locate32/", and added that location to my Windows %PATH%.

Step 2. Tell Emacs where to find it

In Emacs, set the value of the locate-command variable to wherever you ended up putting it. Here’s where it is on my machine:

(setq locate-command "c:/Users/rml/Programs/locate32/locate.exe")

Step 3. Locate all the things

Now when you run the M-x locate command from inside Emacs, it should give you a Dired buffer of results, the same way it does on other systems. Because it’s Dired, you can hit enter on a filename to visit it or mark files in various ways and then operate on them.

Here’s what it looks like on my Windows 10 laptop if I search for the text “svn”:


How to Sync your Opera 12 bookmarks, history, and mail using Dropbox


In this tutorial I’m going to show you how to sync your Opera 12 bookmarks, history, and mail using Dropbox. It involves doing some annoying things to your files (symlinking, etc.) so that Dropbox does the hard work of keeping your bookmarks, mail, history, etc., updated across your various computers. On the bright side, you should only have to do it once.

This post assumes you are a Dropbox user, and you have Opera 12 installed on multiple computers. It doesn’t cover mobile devices, since there was never a mobile version of Opera’s desktop browser.

These instructions work for Linux and the Mac. I would like to do this on my Windows laptop too, but I haven’t been able to get it to work yet. I can’t seem to get Opera to use a link to a folder as if it’s a real folder. If someone knows how to do this, feel free to leave a comment.

One more thing:


OK, now that I’ve shouted a disclaimer at you, let’s do this.

A note on using Dropbox

You may have some concerns about Dropbox’s file synchronization messing up your stuff. For what it’s worth, I’ve been doing this for several months now, and have found that for the most part it just works. In my experience Dropbox basically just handles file updates with no drama.

If it does encounter drama (e.g., finds that it can’t handle a conflict between two different versions of a file), it creates a new version of the file called something like “autosave\ (glamdring2's\ conflicted\ copy\ 2016-02-27).win“, where “glamdring2” is the name of the computer with the conflicted file.

This means you can manually fix things if you have to, but you basically never have to as long as you take care to shut down Opera on computer A and wait until Dropbox is fully synced to start Opera on computer B. This normally takes just a few seconds.

Remember, you should not be doing this with your only copy of your Opera folder. You need to keep regular backups of your Opera folder, and syncing is not a backup.

Step 1. Find your Opera folder

Because Opera is a pretty sane app, it stores all of its junk in one folder (with the exception of the Mac version, about which more below).

Depending on your platform, you’ll find the folder in different places. For more information about where your version of Opera stores its files, see Files used by Opera.

On Linux, it’s easy. Everything is in


On Mac, there is a slight wrinkle. Opera 12 stores your Opera prefs and bookmarks in one place, and your mail in another. This means we need to get them all together in one place so we can sync them with Dropbox.

According to the link above, here’s where your bookmarks, history, etc. are stored if you’re a Mac user:


And it stores your mail in:

~/Library/Application Support/Opera

This is because (according to the docs), user data of “significant size” should go into this other random folder. Um, okay.

In any case, in order to get your Mac install of Opera 12 to work with the actual mail you’ll be syncing in your Dropbox folder, you need to do some goofy stuff with symbolic links, namely:

$ cd ~/Library/Application Support/Opera/
$ mv mail ~/Library/Opera
$ ln -s ~/Library/Opera/mail .

Now everything should all be in ~/Library/Opera (Mac) or ~/.opera (Linux).

Step 2. Copy your Opera folder into Dropbox

Now that we have all of our Opera things in one place, let’s copy the single Opera folder into Dropbox and link it back to wherever your Opera app is expecting the folder to be. On Linux you would do something like this in your terminal – note that Opera should not be running when you do this:

$ mv ~/.opera ~/.opera.bak # Minimal backup copy, you should really do more
$ cp -R ~/.opera.bak ~/Dropbox/opera_config

For Mac it’s pretty similar:

$ mv ~/Library/Support/Opera ~/Library/Support/Opera.bak # Minimal backup copy
$ cp -R ~/Library/Opera.bak ~/Dropbox/opera_config

In English, this:

  • Makes a backup of your Opera folder so if something gets messed up, you can put things back the way they were
  • Copies the backup into your Dropbox folder, where it can be synced across all of your machines

Step 3. Link the folder from Dropbox back to where the app wants it

Now we need to make it look to the Opera 12 app like everything is totally normal. We’ll do that by creating a link from the folder sitting in Dropbox back to where the app expects it to be.

Again, I’m really happy to hear from people about how to do this on Windows. Thus far all of my attempts have failed, and the way Windows handles what it calls “links” seems basically Crazytown. But it’s probably just that I don’t understand them well enough.

Anyway, here’s how you do the linking on Linux:

$ ln -s ~/Dropbox/opera_config ~/.opera

And on Mac:

$ ln -s ~/Dropbox/opera_config ~/Library/Opera

Step 4. Profit?

At this point you should be syncing your mail, bookmarks, history, and sessions across computers. When you shut down Opera 12 on your work machine (a Mac laptop), you can open up Opera 12 on your home workstation running Linux and be in the same session, looking at the same tabs and emails. Everything should just magically work.

If it doesn’t, please let me know in the comments and I’ll try to help.

How to Install the Pentadactyl Firefox Add-On


(Wilkie Reservoir, Queensbury, NY)

This post describes how to install the latest nightly build of Pentadactyl, a browser add-on for Firefox that gives it Vim-like keybindings and behavior.

These instructions are current as of the date of this post. I’m using Firefox 44.0.2 on the release channel as I write this.

On This Page

Step 1. Turn off Add-on Signing

In Firefox, open about:config. You may have to click through a nanny warning about voiding your warranty.

In the text area at the top of the config screen, type xpinstall.signatures.required. This will filter out all of the other options.

Below the text area, double-click on the xpinstall.signatures.required row, which will change the Value to false (it defaults to true).

Step 2. Download the Add-on

Go to the Pentadactyl website, click nightly builds to get the latest version (sometimes the other downloads are outdated), and download the file pentadactyl-latest.xpi.

To install the extension directly from the downloaded file:

  • Go to about:addons
  • Click the gear icon at the upper right-hand side of the screen
  • A dropdown menu will appear; select Install Add-on From File
  • A popup will appear, asking if you want to install this unverified add-on; click Install

If the extension installs, it will change the Firefox UI a lot. It will look like the GUI is gone completely, and it can be a little confusing at first. Type :help to read the built-in docs. If that doesn’t work, type :open http://5digits.org/help/pentadactyl/ to read the online version.


Pentadactyl could not be installed because it is not compatible

If the add-on installation fails because of a version mismatch, you’ll need to do the following:

Open the XPI file (which is basically just a zip file) in Vim, Emacs, or something else that can edit the contents of zip files directly. Edit the install.rdf XML file so the em:maxVersion attribute is a number equal to or higher than your Firefox version:


I can’t turn off extension signing

Mozilla are planning to remove the ability to turn off extension signing requirement in an upcoming version. If you are reading this after that has happened, a possible workaround is to install Firefox ESR (Extended Support Release), which is aimed at enterprise or education environments and lags several development cycles behind the “consumer” versions.

(The above photo was taken by me and is available under a Creative Commons license.)