HOWTO

HOW TO : Use curl to connect to a Unix socket

Today I learned a incredibly useful trick for debugging web applications that don’t use standard TCP/IP networking. While we usually think of curl as a tool for fetching data over http:// or https:// via a port like 80 or 443, it is also fully capable of communicating over Unix Domain Sockets.

Why use Unix sockets?

You can use Unix sockets instead of TCP to proxy application servers. Sockets are often faster and more secure for local inter-process communication because they avoid the overhead of the network stack and can be protected by standard file permissions.

The challenge arises when you want to test the application server directly without going through the public-facing proxy. That is where this curl command comes in.

The Command

To request a page from a service listening on a Unix socket, use the --unix-socket flag followed by the path to the socket file:

curl --unix-socket /var/www/app/app.sock http://localhost/

The --unix-socket flag tells curl to ignore the standard DNS resolution for the hostname and instead connect directly to the file path provided, which in this case is /var/www/app/app.sock.

The http://localhost/ part of the command is still required because curl needs to know which protocol to use and what to put in the Host header of the HTTP request. Even though the data is traveling through a file on your hard drive rather than a network card, the application server still expects a valid HTTP request format.

This is a lifesaver for troubleshooting “502 Bad Gateway” errors. By bypasssing Nginx and hitting the socket directly, you can determine if the issue lies with the application server itself or the proxy configuration. If the command above returns the expected HTML, you know your backend is healthy and the problem is likely in your nginx .conf file.

February 15, 2026 by HOWTO Linux Technology 0

HOW TO : Launch tmux on SSH login

I’m terrible at remembering to start tmux when I SSH into servers. Then invariably, my connection drops mid-compile or during a long-running test, and I lose everything :-(.

The solution? Just make tmux start automatically when you SSH in. Here’s how.

The Problem

You SSH into your server, start working, and then:

  • Your WiFi hiccups
  • Your laptop sleeps
  • You close the terminal by accident

And poof—all your work is gone. tmux solves this by keeping your session alive on the server, but only if you remember to actually start it.

The Solution

Add a simple check to your ~/.bashrc that auto-launches tmux when you connect via SSH.

# Auto-launch tmux on SSH connection
# To skip: either detach from tmux (Ctrl+b, then d) or set TMUX_SKIP=1 before connecting
# Example: TMUX_SKIP=1 ssh user@host
if [[ -n "$SSH_CONNECTION" ]] && [[ -z "$TMUX" ]] && [[ -z "$TMUX_SKIP" ]] && command -v tmux &> /dev/null; then
   tmux attach-session -t default || tmux new-session -s default
fi

Add this to the end of your ~/.bashrc file.

How It Works

The script checks four conditions before launching tmux:

  1. -n "$SSH_CONNECTION" — Are you connecting via SSH? (Doesn’t trigger for local terminal sessions)
  2. -z "$TMUX" — Is tmux not already running? (Prevents tmux-inception)
  3. -z "$TMUX_SKIP" — Did you explicitly skip tmux? (More on this below)
  4. command -v tmux — Is tmux actually installed?

If all checks pass, it tries to attach to an existing session named “default”. If that session doesn’t exist, it creates one.

Skipping tmux When Needed

Sometimes you just want a plain shell—for quick commands, debugging, or whatever. Two ways to skip:

Option 1: Set an environment variable

TMUX_SKIP=1 ssh user@server

Option 2: Detach after connecting

Ctrl+b, then d

This drops you to a regular shell without killing the tmux session.

Why This Setup?

  • Named session: Using default as a session name makes it easy to reconnect
  • Attach-or-create: The || operator means it’ll create the session only if it doesn’t exist
  • No exec: Some examples use exec tmux ... which replaces your shell entirely. I prefer not doing that—it makes skipping harder and can be annoying for scripted SSH commands

That’s it. Now you can SSH in, disconnect whenever, and pick up right where you
left off. No more lost work from dropped connections.

February 12, 2026 by HOWTO Linux Technology 0

HOW TO : Reduce phone usage

I know this is not really practical :-).. But hear me out

Every 6 months, switch from an Android to an iPhone as your primary phone. You’ll be amazed at how much free time you suddenly get.

The Reset Button

When you switch ecosystems, you get a blank slate. No apps. No habits. No notifications. Your phone is boring. And that’s the feature.

Most phone usage is pure inertia. You open Instagram because it’s there. You check email because the badge is red. But when you switch phones, those habits become a bit tougher to adhere to.

Starting Fresh

When setting up the new phone, be intentional:

  • Grayscale icons. Colors are designed to grab attention. Grayscale strips that away. Your apps become tools, not emotional triggers.
  • Only install what you need. Don’t install “just in case.” Start with essentials. Everything else can wait.
  • Disable notifications. Disable all notifications except calls and messages from people you know. You’ll notice which apps you actually miss.

The cycle starts afresh

Over time, you’ll add apps. But you’ll add them consciously, not because they came pre-installed. And as your collection grows, you’ll naturally develop habits around them. And that’s when the addiction/distraction cycle kicks in again.

Why (I believe) This Works

When you have unlimited options, you default to what’s easiest. When you have to choose, you choose what matters.

Most productivity advice tells you to optimize your existing system. But you’re fighting accumulated habits that have grown over time. Switching phones is different, it’s a reset, not optimization.

Give it a try.

January 26, 2026 by HOWTO Humanity 0

HOW TO : Run Anthropic Computer Use Tool on a Windows Machine

Anthropic released their new Claude Sonnet 3.5 model yesterday that has a new capability to control computers. Computer Use capability allows Claude to directly interact with computer interfaces, enabling tasks like web browsing, data analysis, and file manipulation – all through natural language instructions. Similar to tools, but now you don’t have to define specific tools. I think this opens up a whole new window of opportunities to leverage LLMs for.

Anthropic shared a quick start guide to run the model in a container, but the instructions are for Mac/Linux based workstations. I had to make some tweaks to run them on a windows workstation.

Documenting them for anyone that might be trying to do the same

  • Install Docker Desktop
  • Open a command prompt
  • Run the following command to set your anthropic api key system variable
    • set ANTHROPIC_API_KEY=YOUR-ANTHROPIC-KEY
  • Run the following command to start the docker container
    • docker run -e ANTHROPIC_API_KEY=%ANTHROPIC_API_KEY% -v $HOME/.anthropic:/home/computeruse/.anthropic -p 5900:5900 -p 8501:8501 -p 6080:6080 -p 8080:8080 -it ghcr.io/anthropics/anthropic-quickstarts:computer-use-demo-latest
  • Launch the streamlit app by opening this URL in your browser http://localhost:8080/

October 24, 2024 by HOWTO 0

HOWTO : Bulk deletes in vi

Use “dG” command, if you want to delete all lines in a file starting from the line under the cursor in vi.

Additional commands to delete lines

  1. dd deletes the whole line under the cursor.
  2. xdd deletes multiple (x) lines, starting at the cursor. For example 10dd deletes 10 lines
  3. d$ deletes to the end of the line, starting at the cursor.
June 27, 2023 by HOWTO 0

HOW TO : Create free clipart

One can leverage the explosion of generative AI art engines to create your own clip art.

  • Create an image in MidJourney (you can get free credits to create up to 200 images)
    • You can add “clipart” to any image description to get good results
  • Use Removebg to remove any background from the image. (500×500 pixel png images are free)
  • enjoy 🙂

Here’s a clipart that I created using the prompt “moscow mule drink illustration, clipart”

December 9, 2022 by HOWTO 0

HOWTO : Query json data in SQLite

A self note for querying json data in SQLite. BTW, I think SQLite is an under utilized and under appreciated swiss army tool for data storage and manipulation. And thanks to Richard Hipp, it is free.

If you have a column defined as a json type in your SQLite database, quickest way to search for the data is json_extract. A full set of functions available are documented at https://www.sqlite.org/json1.html

If you have a column named family_details in a table family with the following json in it as an example 

{
	"father": {
		"name": "dad",
		"birthday": "1/1/2000",
		"pet_name": "daddy"
	},
	"mother": {
		"name": "mom",
		"birthday": "1/1/2001",
		"pet_name": "mommy"
	},
	"sons": [
		{
			"name": "son_one",
			"birthday": "1/2/2020",
			"pet_name": "sonny_one"
		},
		{
			"name": "son_two",
			"birthday": "1/2/2021",
			"pet_name": "sonny_two"
		}
	],
	"daughters": [
		{
			"name": "princess_one",
			"birthday": "1/2/2020",
			"pet_name": "princy_one"
		},
		{
			"name": "princess_two",
			"birthday": "1/2/2021",
			"pet_name": "princy_two"
		}
	]
}

and you want to print the name of the father, you can use

select json_extract(family_details, '$.father.name') as father_name
from family

json_extract uses the name of the column and the json node as parameters. In this case, we used $(which denotes the root), father and name (under father) as the json node.

April 13, 2021 by Databases HOWTO Technology 0