Ashley Connor's TIL

Installing ssh-copy-id on a Synology NAS

Thu, 29 Oct 2026 17:20:21 GMT

ssh-copy-id isn’t installed on DSM 7+ and is unavailable from the Synology Package Center (or the SynoCommunity Package repo).

I wanted to copy SSH keys between my DS420+ and my other servers so let’s install the tool to do that.

mkdir -p "$HOME/.local/bin" "$HOME/.ssh"
chmod 700 "$HOME/.ssh"

curl -fL \
  https://raw.githubusercontent.com/openssh/openssh-portable/master/contrib/ssh-copy-id \
  -o "$HOME/.local/bin/ssh-copy-id" &&
chmod 755 "$HOME/.local/bin/ssh-copy-id"

Validate the installation and add to the PATH

"$HOME/.local/bin/ssh-copy-id" -h

# make the command available on the PATH in the current session
export PATH="$HOME/.local/bin:$PATH"

# [optional] persist it across new sessions
echo 'export PATH="$HOME/.local/bin:$PATH"' > ~/.profile

Finally we can call it with the key we wish to copy

ssh-copy-id -i "$HOME/.ssh/id_ed25519.pub" username@destination

If you don’t have a key yet, generate one using ssh-keygen which is installed on DSM 7+

ssh-keygen -t ed25519

I also add an SSH conf entry to make it easier to connect to each server

Host desktop
    HostName <ip_address>
    User <user>
    IdentityFile /var/services/homes/<user>/.ssh/id_ed25519
    IdentitiesOnly yes

Then we can simply call ssh desktop to connect.

Automatically Activating a Virtual Environment with direnv

Sat, 01 Mar 2025 08:00:00 GMT

When working with Python projects, activating a virtual environment (venv) manually every time you switch to a project directory can be tedious. Fortunately, direnv provides a way to automate this process.

Automatically Activating a Virtual Environment

When navigating to a project’s root directory, you likely want the associated virtual environment to activate automatically. A common approach is using direnv with a .envrc file:

source .venv/bin/activate

With this setup, direnv loads the virtual environment when you enter the directory and unloads it when you leave:

❯ cd blog/
direnv: loading ~/Projects/blog/.envrc
direnv: export +VIRTUAL_ENV +VIRTUAL_ENV_PROMPT ~PATH
❯ cd ..
direnv: unloading

An Official Approach

A better and officially supported method for achieving this in direnv is:

export VIRTUAL_ENV=".venv"
layout python

This approach leverages direnv’s built-in layout function which is available for range of programming languages, editors, & tools.

Reusing the Setup Across Projects

For even greater convenience, you can define a custom function to standardize environment activation across all your projects. Check out the direnv wiki for more details.

How to strip DRM from Audible audiobooks

Fri, 02 Dec 2022 08:00:00 GMT

I have a subscription with Audible which allows you to download an audiobook a month for keeps.

These books can be listened to on the Audible app but if you want to use another app then it needs to support Audible’s DRM system.

The particular app I wanted to use did not support DRM so I chose to remove the DRM from my purchases books.

To do this we’ll use a Python project audible-cli.

Install this using pip:

$ pip install audible-cli

Once installed we can run audible quickstart - this will start a wizard that creates a configuration file.

Next we can run audible library list to list our Audible library and choose the audiobook we want to download.

$ audible library list
...
B015ELUYL4: Kurt Vonnegut: Slaughterhouse-Five

We can then download the aax file using the download subcommand:

$ audible download --aax --asin B015ELUYL4

Once downloaded we need the activate bytes to decode the DRM:

$ audible activation-bytes
7224181c

With these bytes we can convert the aax to mp3 without DRM:

$ ffmpeg -activation_bytes 7224181c -i Slaughterhouse-Five-LC_64_22050_stereo.aax Slaughterhouse-Five-LC_64_22050_stereo.mp3

Alternatively AAXtoMP3 does a great job of converting the aax to a variety of codecs (AAC command shown below) whilst keeping metadata and cover-art intact.

$ bash AAXtoMP3 -a -A 7224181c Slaughterhouse-Five-LC_64_22050_stereo.aax

About Elixir Pattern Matching in Anon Functions

Thu, 01 Dec 2022 08:00:00 GMT

I was watching a recording of José Valim livecoding solutions to the 2021 Advent of Code problems and I noticed a piece of code that I didn’t know was valid Elixir syntax.

In Elixir, anonymous functions can use pattern matching on their input to execute different code based on the match.

This works similarly to a cond statement:

cond do
  2 + 2 == 5 ->
    "This will not be true"
  2 * 2 == 3 ->
    "Nor this"
  1 + 1 == 2 ->
    "But this will"
end

This pattern matching capability enables code like this from the video:

input
|> String.split("\n", trim: true)
|> Enum.map(fn
  "forward " <> number -> {:forward, String.to_integer(number)}
  "down " <> number -> {:down, String.to_integer(number)}
  "up " <> number -> {:up, String.to_integer(number)}
end)
|> Enum.reduce({ _depth = 0, _position = 0}, fn
  {:forward, value}, {depth, position} -> {depth, position + value}
  {:down, value}, {depth, position} -> {depth + value, position}
  {:up, value}, {depth, position} -> {depth - value, position}
end)
|> then(fn {depth, position} -> depth * position end)

How to remove Self Control

Sat, 26 Nov 2022 08:00:00 GMT

I was toying with applications that block time-wasting websites in the hope that the friction would lead me to be more productive.

Self Control is one solution.

Annoyingly Self Control isn’t easily stopped once a timer is started, and the application doesn’t come with an uninstaller.

Usually when uninstalling apps on OSX I make use of a very helpful freeware program App Cleaner.

App Cleaner found most of the installed files and removed them, however if you’ve already started a blocking timer then there are a few other things that we need to clean up.

Stop Self Control from automatically restarting - launchctl unload -w /Library/LaunchDaemons/org.eyebeam.selfcontrold.plist (App Cleaner had already removed the plist file).
Kill the Self Control process - sudo killall SelfControl.
Remove the timer lock file - sudo rm /etc/SelfControl.lock.

With the process dead and unloaded from launchd we can now remove the firewall rules that were added.

First edit the root pf config file sudo vim /etc/pf.conf and remove the load anchor "org.eyebeam" from "/etc/pf.anchors/org.eyebeam" entry.

Then remove the anchor file sudo rm /etc/pf.anchors/org.eyebeam.

Reload pf with sudo pfctl -f /etc/pf.conf.

Finally we need to remove any host entries that Self Control added by removing the Self Control block from the /etc/hosts file sudo vim /etc/hosts.

Websites previously blocked should now be accessible. To overcome DNS caching issues you may need to run sudo killall -HUP mDNSResponder.

How to run a shell script over images with Automator

Sun, 13 Nov 2022 08:00:00 GMT

When posting screenshots of text to Twitter sometimes the thumbnail gets messed up and clips the content making it unreadable without clicking to expand.

I was using a handy script I’d put together that leverages ImageMagick to resize any image to 1600x900px, which is the optimal size for Twitter feeds.

The script also uses ImageMagick’s histogram feature to fill in any empty space using the dominant color of the image. This is expecially hand when clipping text that has a background other than white, like the Financial Times.

Executing the script is what this post is about.

Firing up the command line, looking for the image and running the script with the image path as an argument is tedious.

It’d be much nicer if we could right click an image or a selection of images and resize them right in Finder.

Enter Automator.

Automator allows us to create a “Quick Action” which can be accessed using a right-click of a mouse or a two-fingered click of the trackpad.

In the workflow options we will select:

Workflow receives current “Image files” in “any application”
Choose any “Image”
Choose any “Color”

Then in the Actions side-menu we will search for “Run Shell Script” and drag it into our workflow.

For the Shell I’ve selected “/bin/bash” and for Pass Input “as arguments”.

I then paste in my script from before.

The workflow then looks like this:

Then once we save the Quick Action becomes available in our conext menu:

An example of the resize:

Before

After