The problem#

Previously, I wrote a script for opening and immediately focusing xfce4-appfinder. But xfce4-appfinder will notice if it's already open and just assume you want to use the existing window. Even if it's on a different desktop. And therefore attempting to focus it will either do nothing or switch to that desktop, neither of which is desirable.

The solution#

The actual solution I settled on is more of a workaround than a solution: having xfce4-appfinder on a different desktop doesn't really make sense, so I just set it to be on all desktops (specified as the non-existent desktop -1), so it would never be on the wrong desktop:

xdotool set_desktop_for_window "$winid" -1

To actually move the window to the current desktop, replace xdotool windowactivate "$winid" with

desktop="$(xdotool get_desktop)"
win_desktop="$(xdotool get_desktop_for_window "$winid")"
if [[ "$desktop" == "$win_desktop" ]]
then
  xdotool windowactivate "$winid"
else
  xdotool set_desktop_for_window "$winid" -1
  xdotool set_desktop_for_window "$winid" "$desktop" \
          windowactivate "$winid"
fi

Although this assumes that you know the $winid of the window you want to move. If you have just the title it works just as well to use

wmctrl -R "Application Finder"

The details#

The problem#

Last week, I mentioned that I needed a hack to kill xprop that seemed like it should be unnecessary. Specifically, I had its output piped to a Bash while read loop and once that had found a line to act on, there was no further need to get more lines from xprop, but break or exit didn't result in xprop exiting.

The solution#

Use $BASHPID to get the actual PID of the subshell, ps to climb the process tree to the appropriate parent and pkill to kill its children:

some_pipeline |
  while read -r line
  do
    # Do whatever until ready to kill the pipe...
    # ... then kill it:
    ppid=$BASHPID
    ppid=$(ps -o ppid:1= "$ppid")
    pkill -9 -P "$ppid" 
  done

Rewrite appfinder-and-focus.sh from last time:

#!/usr/bin/bash
xprop -spy -root _NET_CLIENT_LIST | stdbuf -oL head -2 |
  while read -r l
  do
    winid="${l/#*, /}"
    if [[ $(xdotool getwindowname "$winid") == \
      "Application Finder" ]]
    then
      xdotool windowactivate "$winid"
      ppid=$BASHPID
      ppid=$(ps -o ppid:1= "$ppid")
      pkill -9 -P "$ppid" 
    fi
  done) 2>/dev/null &
xfce4-appfinder &

The details#

The problem#

I have my window manager set to not focus new windows because I dislike having a new window pop up while typing and having the keystrokes surprisingly sent to the new window instead of the one I thought I was typing in. While this is usually what I want, this does mean extra clicks when I did mean to open the new window.

This is particularly bad for xfce4-appfinder (or any other application launcher), since the purpose to be able to set a global keyboard shortcut like Super+Space so you can press that combination and quickly type in the application or action you want (or, even better, type just the first few characters of its name). And since it's being intentionally launched by a keyboard shortcut, there's no real concern of it grabbing keyboard focus unexpectedly.

The solution#

Put the following script in a file appfinder-and-focus.sh and set the keyboard shortcut to run it instead of just running xfce4-appfinder directly:

#!/usr/bin/bash
(xprop -spy -root _NET_CLIENT_LIST | stdbuf -oL tail -n +2 |
  while read -r line
  do
    winid="${line/#*, /}"
    if [[ $(xdotool getwindowname "$winid") == \
        "Application Finder" ]]
    then
      xdotool windowactivate "$winid"
    fi
  done) 2>/dev/null &
xfce4-appfinder &

# Wait for window to appear, then kill xprop.
xdotool search --sync --name "Application Finder" >/dev/null
pkill -P "$(jobs -p %1)"

The details#

The problem#

Previously, I figured out how to extract Tametsi's puzzles, but I wanted to make something user-friendly that made use of those puzzles, so I didn't want to require people to install something or run console commands. I had also figured out how to get Java programs running in a browser, so I figured it would be straightforward to combine the two. As you may have guessed from this paragraph being in the "the problem" section, it was not. Specifically, while the Java command-line will read tametsi.exe as a JAR file, Doppio gives the error

Invalid Zip file: Central directory record has invalid signature

The solution#

As a workaround, use a different library to unzip tametsi.exe. There's no need to present it as a JAR file instead of a directory, so no need to rezip it:

var fs = BrowserFS.BFSRequire("fs");

async function unzipToDirectory(zipfile, dir) {
  const z = new zip.fs.FS();
  await z.importBlob(zipfile);

  async function extract(z, dir) {
    fs.mkdir(dir, true)
    if (z.directory) {
      const childDir = z.name
        ? `${dir}/${z.name}`
        : dir;
      for (const child of z.children) {
        await extract(child, childDir);
      }
    } else {
      fs.writeFileSync(
        `${dir}/${z.name}`,
        new buffer(await (await z.getBlob()).arrayBuffer()));
    }
  }

  await extract(z.root, dir);
}

To call that, in the uploadFile() function, replace the reader.onload with

await unzipToDirectory(f, process.cwd() + '/tametsi');

The details#

The problem#

Slashdot recently made a change to their ad code that made the site completely fail to load for me, showing the message

Failed to load website properly since html-load.com is blocked. Please allow html-load.com

and then blaming ad blocking:

This page could not be loaded properly due to incorrect / bad filtering rule(s) of adblockers in use. Please disable all adblockers to continue using the website. (click OK if you'd like to learn more)

I could see the page loaded just fine behind those messages, so it was obviously a lie. But the page continually reloaded if I tried to dismiss those pop-ups, so the site was unusable.

(Actually, this appears to have been disabled in the time it took me to write this blog post, so I guess this is no longer needed. Although it may be applicable to other websites using the same or similar mechanisms.)

The solution#

Install this user script. I have only tested it with Greasemonkey on Firefox so it require modification to work on other user script managers or browsers.

The details#

The problem#

Java and JavaScript are insufficiently easily confused. I had some code I wanted to run on the user's computer and not the server, and it specifically had to be in Java to reference a library written in Java. I found¹ Doppio, a JVM written in TypeScript, but it had bitrotted enough that I was having trouble getting it to run, despite confirming it did what I wanted using the official demo, which provides an in-browser console-like interface.

The solution#

I was able to piece together a working simple page using Doppio, modified from the official example. It's in a repository on GitHub and should be straightforward to modify for your needs.

The details#

The problem#

Last time, I built a user script that could run on the Folklife 2024 schedule page¹ and reorganize it so it would display the schedule as a grid. But it was brittle and awkward to use because it requiring careful ordering of the interactions with the page and reloading to view a different day's schedule.

The solution#

After failing to come up with an appropriate place to add an event handler, I gave up and took a different approach. I modified the script to work fine if it's run multiple times (and exit quickly if there's no work to do), even if the page is not in a valid state, and then simply set it to rerun every half second. Definitely a hack, but it worked.

Here's the final version of the user script and the Git repo showing the version history.

The details#

The problem#

The Folklife 2024 schedule page¹ is a schedule grid: locations are along the x-axis and time is along the y-axis. Except it's not actually arranged as a grid: each column is just stacked in order with no correspondence to the other columns or the absolute times of the events. Glancing at the code, I noticed the schedule data was available in JSON format, so it should be pretty easy write a user script to display the schedule in a slightly different format.

But when I went to actually make the changes, I found the code is obfuscated React that turned out to be tricky to modify.

The solution#

I was able to write this user script (git repo), which changes the display from the columns of events to a schedule grid. It even works on Firefox mobile, although only if you explicitly request the desktop site.

The details#

The problem#

I had recently done an apt upgrade that included upgrading ZFS and noticed zpool status showed a weird "(non-allocating)" message, which seemed concerning:

$ zpool status
  pool: tank
 state: ONLINE
config:

    NAME         STATE     READ WRITE CKSUM
    tank         ONLINE       0     0     0
      mirror-0   ONLINE       0     0     0
        ata-***  ONLINE       0     0     0  (non-allocating)
        ata-***  ONLINE       0     0     0  (non-allocating)

errors: No known data errors

The solution#

This forum thread suggested the error may be due to a version mismatch between the ZFS tools and the kernel module. I confirmed there was a mismatch:

$ zpool --version
zfs-2.2.3-2
zfs-kmod-2.1.14-1

The easy way to load the new version of a kernel module after an update is to reboot the computer. But if you don't want to do that, here's the general outline of the commands I ran to unload and reload ZFS (run as root):

# Stop using ZFS
$ zfs umount -a
$ zpool export tank
$ service zfs-zed stop
# Remove modules
$ rmmod zfs
$ rmmod spl
# will show error: rmmod: ERROR: Module spl is in use by: ...
# repeatedly rmmod dependencies until spl is removed.

# Reload ZFS
$ modprobe zfs
$ service zfs-zed start
$ zpool import tank

The details#

The problem#

I use KeePassXC as my password manager in Firefox and while sometimes the connection between Firefox and KeePassXC drops and I have to explicitly click reconnect, it recently stopped working entirely.

The solution#

Install the keepassxc-full package instead of the keepassxc package. If you get the browser extension via the webext-keepassxc-browser package, then your package manager will automatically get the right one.

(This only applies to Debian Sid and Trixie or newer.)

The details#