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Comment by pdpi | Hacker News Reader

This is almost certainly due to a windows limitation, which is in turn caused by compatibility for a DOS hack where a bunch of devices were visible through special file names. CON is the more famous one of those.

Microsoft still recommends avoiding those file names. https://docs.microsoft.com/en-us/windows/win32/fileio/naming...

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Back in the 90s we had novell intranetware, and internet explorer on our computer room machines which opened up on login.

One IT lesson, I changed the front page it opened to something like "<img src='c://con/con'>", very amusing :D

Nowadays I'd probably be arrested.

Worse: back in the day, you could type raw HTML into AOL Instant Messenger. Notably, being able to construct a link with whatever address you pleased, including `file://c:\con\con`.

Not just that, AOL allowed playing sound files from within a chat room. If a user sent `{s gotmail`, it would play the `gotmail.wav` file on the computer of each person currently in the chat room. So, sending `{s /con/con` or `{s /aux/aux` to that chat would instantly crash the computer of everyone in the chat, causing a BSoD. It was great fun if you were an obnoxious kid, and generally super frustrating for anyone trying to chat.

There was something similar with popular irc clients on windows in the late 90s early 2000s. There was a direct file transfer mechanism called dcc. If you forged a request for con/aux device files you could send instructions to the person's printer or modem and do all sorts of interesting mischief.

IIRC windows 9x would instantly bluescreen if you tried to open c:\con\con , probably because of a bug in the filesystem driver.

These are old CP/M filenames that DOS reserved for cross-compatibility. They "exist" in every single directory, as CP/M was a directory-less OS.

This exact issue bit me in the arse at my old job when I created a directory called Aux in one of our git repositories on my Linux machine and suddenly nobody running Windows could pull from it without a fairly cryptic error. It's weird to think all that debugging was caused by a decision made back in the '70s for CP/M which eventually made its way into Windows via DOS.

Why only Win32 — Azure Kubernetes had this limitation under some circumstances, even a few years ago[1]. Anyone know if this issue is still present?

[1] https://news.ycombinator.com/item?id=17703371

What were the PRN and AUX files used for?

PRN was for the printer.

AUX is for "auxiliary" (aka "misc."/"other") device - i.e. any other bit of unspecified random hardware you'd managed to hook up with a custom driver by yourself.

AUX is just a synonym for COM1, i.e. first serial port in DOS/Windows.

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