Posts tagged "computing":

The Danger of fuzzy matching over one's PATH

Awhile back I noticed my personal mnt/ directory, my (empty) personal tmp/ directory, and a few symbolic links disappeared from my home directory. I only noticed because I use unison¹ to synchronize my desktop and laptop homedirs. The actual amount of removed directories and symbolic links were staggering, and it costed me five minutes of extra effort to search through the unison UI to ignore files I don’t want to synchronize. Repeat this a few times a day, with the problem occurring at seemingly random intervals, and you’ve wasted minutes out of every day, which adds up to hours every month.

For months I had not figured out what the problem was. By chance I had noticed while using my application launcher, I had accidentally not ran links -g ² but instead had ran cleanlinks. I wonder to myself what was I running by accident, as I had done this before, but had not thought anything of it, assuming it was a program that would print usage or perform a no-operation by default.

I was wrong.

Turns out cleanlinks searches the current working directory for empty directories and broken symbolic links. Both are useful. For example I keep empty directories in ~/mnt/ to mount sshfs stuff, and I prefer to use ~/tmp/ as a work directory because no system scripts will touch it.³ I had a few broken symbolic links scattered about, from weird git repositories working trees to some stale user-level systemd unit links from my archlinux install.

Making things more interesting, if you run cleanlinks --help, or with any flags, it operates as usual. So it’s a mistake to also do cleanlinks /some/directory/i/want/to/clean. As a part of imake,⁴ the old X11 ecosystem build tools, cleanlinks will be installed on many systems and it’s not safe to run it lest you enjoy random stuff being messed about with in your current directory.

How did I manage to run cleanlinks so many times? I did not have links installed on the affected machine. And even after I did install it, I forgot to remove cleanlinks from my rofi runcache. So it had a higher precedence to match than links in certain cases. Hence I ran it a few times on accident even after installing links.

Therefore, I strongly recommend one doesn’t fuzzy match over their PATH. Who knows what other nasty tools ship on your system that will lay waste your productivity, or worse, damage your personal files.

Regardless, I have yet to heed my own warning. Maybe I should just use .desktop files, but then again, maybe there exists a cleanlinks.desktop… Ideally, I’ll create a directory of symlinks to programs I want to launch from rofi. Someday :)

Open URL in existing Qutebrowser from Emacs Daemon on Gentoo

On my Gentoo desktops, I use Emacs Daemon via sys-emacs/emacs-daemon¹ to ensure an Emacs instance is ready to go and always available from boot. This is done via creating a symbolic link like /etc/init.d/emacs.winston to /etc/init.d/emacs which will start Emacs for the given user. See the package README for more details.

A shortcoming of this setup is XDG_RUNTIME_DIR² is not set, as this is set by my Desktop Session - maybe LightDM or consolekit set this? As a result, when I open a URL from Emacs Daemon, it opens a fresh qutebrowser session, loading the saved default session, and making a mess of my workflow.

One approach to fix this might be to instead run Emacs daemon from my .xsession script, but I rather not supervise daemons at the user level; if I were to consider this, I'd be better off to switch to systemd for user-level services anyway.

The solution I came up with is to add some lines to my init.el to ensure XDG_RUNTIME_DIR is set to the expected value:

(defun winny/ensure-XDG_RUNTIME_DIR ()
  "Ensure XDG_RUNTIME_DIR is set. Used by qutebrowser and other utilities."
  (let ((rd (getenv "XDG_RUNTIME_DIR")))
    (when (or (not rd) (string-empty-p rd))
      (setenv "XDG_RUNTIME_DIR" (format "/run/user/%d" (user-uid))))))

(add-hook 'after-init-hook #'winny/ensure-XDG_RUNTIME_DIR)

A strange emacs-ism: (user-uid) returns float or integer, despite the backing uid_t (on *nix) is guarenteed to be an integer type. I'll just assume this'll never return a float. Please contact me otherwise, I'd love to hear about this.

Blink Shell: First Thoughts

As a heavy user of SSH to manage computers and IRC via command line clients, the most used application on my phone besides the web browser is a SSH client. Previously I have used Prompt and it worked, but barely. My issues with Prompt include crashing on emoji spam that is common in certain IRC channels, very slow terminal rendering to the point that watching the output of compiling a large package will cause Prompt to lag uncontrollably for tens of seconds, and a relatively un-intuitive UI. Please note I am referring to Prompt, not Prompt 2¹, which is another problem in itself (the idea I need to pay for the same product but rewritten to actually work is just ludicrous).

Another thing to note before I dig into Blink is I'm not a big fan of mobile devices. They get the job done, but in most cases I rather crack open my netbook and not fight with the learn-by-fiddling mobile UI paradigms most devices have adopted. I am also not a fan of Apple's ecosystem, but I'm pretty content with my iPhone and iPad for my basic use cases: browse the web, chat applications, making phone calls, casual mobile gaming, logging into other computers via SSH.

Enter Blink². This application does a few things differently from other mobile SSH clients. It offers a command-line first user interface. At first I thought this would be painful, but the application's verbs are pretty simple and appear to match up with how one uses ssh and mosh in a terminal emulator. The terminal emulator is responsive, significantly more stable than Prompt, and looks good. I can even load up my favorite font: Droid Sans Mono³ (thanks to its support for loading webfonts via a URL to a CSS file).

Another thing Blink does different is it offers Mosh support⁴. Mosh is an alternative to SSH that can "roam" across networks and device power state changes. One thing to note is Mosh requires SSH to make the initial login, then switches to Mosh which uses a different protocol. When using mosh, I tend to log in once throughout the day. I can then switch networks and mosh will gracefully reconnect as soon as the server is reachable again. In addition, when I sleep my netbook, the session isn't lost (but don't go using this instead of tmux or screen). Instead when I wake my netbook, it also gracefully reconnects to the server. The same is true of Blink's Mosh support. It even appears to save state between changing iOS application states, sans forcing the application to quit (or rebooting your device). This means I only log in once on my phone throughout the day, and the connection is gracefully dropped when the app becomes inactive and reconnects when the app is opened again.

I did notice I crashed Blink after writing non-ascii binary data to the terminal followed by some other operations, but did not manage to reproduce the crash yet. If I do, I am confident I can report the bug and get meaningful feedback too, as Blink has a bug tracker on GitHub⁵. The code is available under GPLv3 (but not to worry, as the single copyright holder can safely relicense it to deploy on the iOS App Store⁶). I could probably build it myself and install that, but I neither own a Mac (or wish to install Mac OS X in a VM) nor want to ever open XCode again even if I had a way to. That life isn't for me. Again, I'm very practical about how I use my iOS devices and don't enjoy using them more than I have to, so I'm willing to pay $20 for an application I'll use every day of my life on this walled garden platform. An added silver lining is this investment goes towards the development of such a great app that appears to have active maintainership.

Note: I did not explore some of Blink's features such as using it a local iOS shell or settings synchronization. YMMV.

GNU C Style

No. Do not use it please! There are far easier-to-read and easier-to-use styles for C!¹

Publishing with org-static-blog

(add-to-list 'auto-mode-alist (cons (concat org-static-blog-posts-directory ".*\\.org\\'") 'org-static-blog-mode))
(setq org-static-blog-publish-title "blog.winny.tech")
(setq org-static-blog-publish-url "https://blog.winny.tech/")
(setq org-static-blog-publish-directory "~/projects/blog/")
(setq org-static-blog-posts-directory "~/projects/blog/posts/")
(setq org-static-blog-drafts-directory "~/projects/blog/drafts/")
(setq org-static-blog-enable-tags t)

(setq org-static-blog-page-header
      "
<link href=\"static/style.css\" rel=\"stylesheet\" type=\"text/css\" />
")

blog.winny.tech {
        root /srv/www/blog.winny.tech
        gzip
        log /logs/blog.winny.tech.log
        git https://github.com/winny-/blog.winny.tech {
                hook /webhook top-secret-password-redacted
        }
}

version: "2.1"
services:
  web:
    image: abiosoft/caddy:no-stats
    ports:  # Expose the webserver ports to the internet
      - "80:80"
      - "443:443"
    environment:
      # This is where caddy places certs after ACME negotiation.
      CADDYPATH: "/etc/caddycerts"
      ACME_AGREE: "true"
    volumes:
      - /srv/caddy/certs:/etc/caddycerts
      - /srv/caddy/Caddyfile:/etc/Caddyfile  # Configuration
      - /srv/www:/srv/www  # the websites
      - /srv/caddy/logs:/logs

Toggle Redshift with Keyboard Shortcut

Redshift is a screen-tinting program that achieves similar goals to the popular f.lux¹ program.

I perused through the redshift man-pages and noticed there is no documented way to toggle redshift. Of course one can click the notification area icon when using redshift-gtk or SIGTERM the redshift process, but neither is very user friendly. (The mouse is not user friendly.) After some awkward DuckDuckGo-ing and Googling I found an obvious solution on the redshift homepage²: simply send SIGUSR1 to the redshift or redshift-gtk process. When using redshift-gtk, one can choose to send SIGUSR1 to either redshift or redshift-gtk.

This is the script I came up with:

#!/bin/sh
set -eu
if ! pkill -x -SIGUSR1 redshift; then
    echo 'Could not find redshift process to toggle.' >&2
    exit 1
fi

After installing the script into my system's PATH, now all I have to do is add a line to my Xbindkeys³ configuration file (~/.xbindkeysrc.scm) such as:

(xbindkey '(Mod4 F2) "toggle-redshift")

Now I can type Mod4-F2 and toggle Redshift.