Back when this mistake was made, There was only one Phone Company, because they hadn't been broken up yet. Ted Bundy was still on the loose. Babe Ruth's home run record was about to fall.
It is 2018 and this error message is a mistake from 1974.
This limitation, which is still found in the very latest Windows 10, dates back to BEFORE STAR WARS. This bug is as old as Watergate.

Back when this mistake was made, There was only one Phone Company, because they hadn't been broken up yet. Ted Bundy was still on the loose. Babe Ruth's home run record was about to fall.
You could do neat things with it like copy data off the serial port into a text file, or print a textfile right from the command line!
You can get infinite zeros from /dev/zero, random bytes from /dev/random, etc!
So directories? you don't need 'em. Instead of directories, you just use different disks.
So they're just "everywhere", effectively.
So if you have FOO.TXT and need to print it, you can do "PIP LST:=FOO.TXT" which copies foo.txt to the "file" LST, which is the printer.
but what about extensions? Here's the problem: programs like to name their files with the right extension.
but the program might try to put .TXT on the end of your filename! LST.TXT isn't the printer, right?
Eh. It's a hack, but it works, and this is just on some little microcomputers with 4k of ram, who cares?
But it was big, so naturally IBM wanted it for some "PC" project they were doing in early 1980
MS purchased Tim Paterson's project and developed it into PC-DOS (which later became MS-DOS, if you're not aware)
It was definitely inspired by CP/M, in a lot of ways.
So QDOS and PC-DOS 1.0 have AUX, PRN, CON, LPT, etc, too!
You need them to keep your massive 10mb hard drive organized, obviously!
with directories, Microsoft could now make a C:\DEV folder... but they didn't.
Special files are in EVERY DIRECTORY with EVERY EXTENSION.
So your "DIR > LPT" trick to print the directory listing doesn't break because you're in C:\DOS instead of A:\
And when Windows 95 was released, it was built on top of DOS. So it naturally inherited this behavior. (Windows 1/2/3 similarly did, but Win95 was much more an OS than they were)
But Windows NT wanted compatibility with DOS/Windows programs. And XP merged the two lines.
So these special files still work, FORTY FOUR FUCKING YEARS LATER
aux.txt
prn.txt
it'll tell you NOPE

CON, PRN, AUX, NUL, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9
https://t.co/1eYQVBKO65


These special-device names are implemented at the OS level, rather than the filesystem level. So they're perfectly valid NTFS filenames, and I was using an NTFS drive in linux.

A couple follow ups:
1. The CP/M inventor's name is "Gary Kildall", not "Gary Kiddal".
Sorry, I posted this at 5am after being in the hospital for like... 8 hours?
It actually required them to be followed by a colon, as if they were a drive name.
So PRN: is the printer, PRN is not.
I didn't mean to imply CP/M did, just DOS, but I don't think I made this clear
PC DOS 1 did support copying to/from special files though, so my general point was correct, even if my example was confusing
It's like you're living on a space station and get trampled by a horse.
More from foone
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On press call, Zuckerberg says FB users "naturally engage more with sensational content" that comes close to violating its rules. Compares it to cable TV and tabloids, and says, "This seems to be true regardless of where we set our policy lines."
Zuckerberg says FB is in the process of setting up a "new independent body" that users will be able to appeal content takedowns to. Sort of like the "Facebook Supreme Court" idea he previewed earlier this year.
Zuckerberg: "One of my biggest lessons from this year is that when you connect more than 2 billion people, you’re going to see the good and bad of humanity."
This is how Facebook says it's trying to change the engagement pattern on its services. https://t.co/3p0PGc912o
.@RebeccaJarvis asks Zuckerberg if anyone is going to lose their job over the revelations in the NYT story. He dodges, says that personnel issues aren't a public matter, and that employee performance is evaluated all the time.
Zuckerberg says FB is in the process of setting up a "new independent body" that users will be able to appeal content takedowns to. Sort of like the "Facebook Supreme Court" idea he previewed earlier this year.
Zuckerberg: "One of my biggest lessons from this year is that when you connect more than 2 billion people, you’re going to see the good and bad of humanity."
This is how Facebook says it's trying to change the engagement pattern on its services. https://t.co/3p0PGc912o

.@RebeccaJarvis asks Zuckerberg if anyone is going to lose their job over the revelations in the NYT story. He dodges, says that personnel issues aren't a public matter, and that employee performance is evaluated all the time.
These past few days I've been experimenting with something new that I want to use by myself.
Interestingly, this thread below has been written by that.
Let me show you how it looks like. 👇🏻
When you see localhost up there, you should know that it's truly an experiment! 😀
It's a dead-simple thread writer that will post a series of tweets a.k.a tweetstorm. ⚡️
I've been personally wanting it myself since few months ago, but neglected it intentionally to make sure it's something that I genuinely need.
So why is that important for me? 🙂
I've been a believer of a story. I tell stories all the time, whether it's in the real world or online like this. Our society has moved by that.
If you're interested by stories that move us, read Sapiens!
One of the stories that I've told was from the launch of Poster.
It's been launched multiple times this year, and Twitter has been my go-to place to tell the world about that.
Here comes my frustration.. 😤
Interestingly, this thread below has been written by that.
Let me show you how it looks like. 👇🏻
Recently I just refunded all Poster's sales from Gumroad. Being that said, I decided to not using that service anymore.
— Wilbert Liu \U0001f468\U0001f3fb\u200d\U0001f3a8 (@wilbertliu) November 19, 2018
Here's a little story \U0001f447\U0001f3fb
When you see localhost up there, you should know that it's truly an experiment! 😀

It's a dead-simple thread writer that will post a series of tweets a.k.a tweetstorm. ⚡️
I've been personally wanting it myself since few months ago, but neglected it intentionally to make sure it's something that I genuinely need.
So why is that important for me? 🙂
I've been a believer of a story. I tell stories all the time, whether it's in the real world or online like this. Our society has moved by that.
If you're interested by stories that move us, read Sapiens!
One of the stories that I've told was from the launch of Poster.
It's been launched multiple times this year, and Twitter has been my go-to place to tell the world about that.
Here comes my frustration.. 😤
So we had to develop technologies like this to barely manage control over limited areas in Iraq's few urban centers. Only ~8 in 100 Iraqi adults owns a personal vehicle. That rate is > 1 car/adult in America yet I have never seen any doctrine paper or work of fiction address this
We've seen and struggled in civil conflicts with instant, local, universal, distributed communications (cell phone era, basically every conflict since 2000). We've seen and struggled in conflicts with instant, global, universal distributed communications (everything since 2011).
The world's most overfunded military and glow in the dark agencies struggle and largely fail to contain conflicts where fhe vast, vast majority of people are locked into a ~5mi radius of their home.
How can they possibly contain a conflict in a nation with universal car ownership and the most developed road network in the world? The average car can travel over 400 miles on one tank of gas, how can you contain the potential of that kind of mobility?
I think that's partially why the system was so freaked out by 1/6. Yes, most of it is histrionics but you don't decide to indefinitely turn your capital into the Baghdad Green Zone with fortifications and 25k troops over histrionics alone.
Hey guys, just a friendly reminder. We're watching you. pic.twitter.com/bGwi1uJBwT
— CIA Metadata Analyst with 8 kids (@CiaKids) September 23, 2019
We've seen and struggled in civil conflicts with instant, local, universal, distributed communications (cell phone era, basically every conflict since 2000). We've seen and struggled in conflicts with instant, global, universal distributed communications (everything since 2011).
The world's most overfunded military and glow in the dark agencies struggle and largely fail to contain conflicts where fhe vast, vast majority of people are locked into a ~5mi radius of their home.
How can they possibly contain a conflict in a nation with universal car ownership and the most developed road network in the world? The average car can travel over 400 miles on one tank of gas, how can you contain the potential of that kind of mobility?
I think that's partially why the system was so freaked out by 1/6. Yes, most of it is histrionics but you don't decide to indefinitely turn your capital into the Baghdad Green Zone with fortifications and 25k troops over histrionics alone.
What an amazing presentation! Loved how @ravidharamshi77 brilliantly started off with global macros & capital markets, and then gradually migrated to Indian equities, summing up his thesis for a bull market case!
@MadhusudanKela @VQIndia @sameervq
My key learnings: ⬇️⬇️⬇️
First, the BEAR case:
1. Bitcoin has surpassed all the bubbles of the last 45 years in extent that includes Gold, Nikkei, dotcom bubble.
2. Cyclically adjusted PE ratio for S&P 500 almost at 1929 (The Great Depression) peaks, at highest levels except the dotcom crisis in 2000.
3. World market cap to GDP ratio presently at 124% vs last 5 years average of 92% & last 10 years average of 85%.
US market cap to GDP nearing 200%.
4. Bitcoin (as an asset class) has moved to the 3rd place in terms of price gains in preceding 3 years before peak (900%); 1st was Tulip bubble in 17th century (rising 2200%).
@MadhusudanKela @VQIndia @sameervq
My key learnings: ⬇️⬇️⬇️
Bubble or Bull Market? Join us for a short presentation and candid one on one on 27th Jan, 4pm with Shri \u2066@MadhusudanKela\u2069. \u2066@VQIndia\u2069 \u2066@sameervq\u2069 #bubbleorbullmarket pic.twitter.com/LBvlBrz6mS
— Ravi Dharamshi (@ravidharamshi77) January 24, 2021
First, the BEAR case:
1. Bitcoin has surpassed all the bubbles of the last 45 years in extent that includes Gold, Nikkei, dotcom bubble.
2. Cyclically adjusted PE ratio for S&P 500 almost at 1929 (The Great Depression) peaks, at highest levels except the dotcom crisis in 2000.
3. World market cap to GDP ratio presently at 124% vs last 5 years average of 92% & last 10 years average of 85%.
US market cap to GDP nearing 200%.
4. Bitcoin (as an asset class) has moved to the 3rd place in terms of price gains in preceding 3 years before peak (900%); 1st was Tulip bubble in 17th century (rising 2200%).
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Keep dwelling on this:
Further Examination of the Motif near PRRA Reveals Close Structural Similarity to the SEB Superantigen as well as Sequence Similarities to Neurotoxins and a Viral SAg.
The insertion PRRA together with 7 sequentially preceding residues & succeeding R685 (conserved in β-CoVs) form a motif, Y674QTQTNSPRRAR685, homologous to those of neurotoxins from Ophiophagus (cobra) and Bungarus genera, as well as neurotoxin-like regions from three RABV strains
(20) (Fig. 2D). We further noticed that the same segment bears close similarity to the HIV-1 glycoprotein gp120 SAg motif F164 to V174.
https://t.co/EwwJOSa8RK
In (B), the segment S680PPRAR685 including the PRRA insert and highly conserved cleavage site *R685* is shown in van der Waals representation (black labels) and nearby CDR residues of the TCRVβ domain are labeled in blue/white
https://t.co/BsY8BAIzDa
Sequence Identity %
https://t.co/BsY8BAIzDa
Y674 - QTQTNSPRRA - R685
Similar to neurotoxins from Ophiophagus (cobra) & Bungarus genera & neurotoxin-like regions from three RABV strains
T678 - NSPRRA- R685
Superantigenic core, consistently aligned against bacterial or viral SAgs
Further Examination of the Motif near PRRA Reveals Close Structural Similarity to the SEB Superantigen as well as Sequence Similarities to Neurotoxins and a Viral SAg.
The insertion PRRA together with 7 sequentially preceding residues & succeeding R685 (conserved in β-CoVs) form a motif, Y674QTQTNSPRRAR685, homologous to those of neurotoxins from Ophiophagus (cobra) and Bungarus genera, as well as neurotoxin-like regions from three RABV strains
(20) (Fig. 2D). We further noticed that the same segment bears close similarity to the HIV-1 glycoprotein gp120 SAg motif F164 to V174.
https://t.co/EwwJOSa8RK

In (B), the segment S680PPRAR685 including the PRRA insert and highly conserved cleavage site *R685* is shown in van der Waals representation (black labels) and nearby CDR residues of the TCRVβ domain are labeled in blue/white
https://t.co/BsY8BAIzDa

Sequence Identity %
https://t.co/BsY8BAIzDa
Y674 - QTQTNSPRRA - R685
Similar to neurotoxins from Ophiophagus (cobra) & Bungarus genera & neurotoxin-like regions from three RABV strains
T678 - NSPRRA- R685
Superantigenic core, consistently aligned against bacterial or viral SAgs
