flinux essentially had the architecture of WSL1, while CoLinux was more like WSL2 with a Linux kernel side-loaded.
Cygwin was technically the correct approach: native POSIX binaries on Windows rather than hacking in some foreign Linux plumbing. Since it was merely a lightweight DLL to link to (or a bunch of them), it also kept the cruft low without messing with ring 0.
However, it lacked the convenience of a CLI package manager back then, and I remember being hooked on CoLinux when I had to work on Windows.
Cygwin is way older than CoLinux. CoLinux is from 2004. Cygwin was first released in 1995.
The problem with Cygwin as I remember it was DLL hell. You'd have applications (such as a OpenSSH port for Windows) which would include their own cygwin1.dll and then you'd have issues with different versions of said DLL.
Cygwin had less overhead which mattered in a world of limited RAM and heavy, limited swapping (x86-32, limited I/O, PATA, ...).
Those constraints also meant native applications instead of Web 2.0 NodeJS and what not. Java specifically had a bad name, and back then not even a coherent UI toolkit.
Just use ssh from Cygwin. DLL hell was rarely a problem, just always install everything via setup.exe.
The single biggest problem it has is slow forking. I learned to write my scripts in pure bash as much as possible, or as a composition of streaming executables, and avoid executing an executable per line of input or similar.
Slow forking is only the second biggest problem IMO. The biggest is the lack of proper signals. There's a bunch of software out there that just isn't architected to work well without non-cooperative preemption.
Meanwhile those that complained about Java, now ship a whole browser with their "native" application, and then complain about Google taking over the Web.
Developing on cygwin, however, was a right pain. If a C library you wanted to use didn't have a pre-built cygwin version (understandable!) then you end up doing 'configure, make' on everything in the dependency tree, and from memory about two thirds of the time you had to edit something because it's not quite POSIX enough sometimes.
Ha ha doing Unix like it was 1989. At the time I thought configure was the greatest of human achievements since I was distributing software amongst Sun machines of varying vintage and a Pyramid. I want to say good times but I prefer now ha ha
Cygwin implements a POSIX API on Win32 with a smattering of Nt* calls to improve compatibility but there's a lot of hoop jumping and hackery to get the right semantics. Fork isn't copy on write, for one thing.
I was a Cygwin user from about 1999 to 2022 or so, spent a little time on wsl2 (and it's what I still use on my laptop) but I'm fully Linux on the desktop since last year.
Nowadays MSYS2, which does depend on cygwin under the hood, offers such a package manager (pacman of Arch Linux) and it is quite a user friendly to run native POSIX binaries on Windows without a linux VM.
In my personal experience, Msys 2 would work great until it didn't. Unless this has changed, from what I remember, Msys2 compiled everything without PIC/PIE, and Windows does allow you to configure, system-wide, whether ASLR is used, and whether it's used "if supported" or always. If that setting is set to anything but off, Msys2 binaries will randomly crash with heap allocation errors, or they do on my system. It happened so much to me when I had actual coreutils installed that I switched to uutils-coreutils even though I knew that uutils-coreutils has some discrepancies/issues. Idk if they've fixed that bug or not; I did ask them once why they didn't just allow full ASLR and get on with things and they claimed that they needed to do non-ASLR compilations for docker.
So, is it like colinux[0], but for pre-NT windows? Neat!
Back when I was still using windows (probably XP era), I used to run colinux, it was kind of amazing, setting up something like LAMP stack on the linux side was a lot easier and then using windows editors for editing made for quite nice local dev env, I think! Could even try some of the X11 servers on windows and use a linux desktop on top of windows.
When I noticed I kept inching towards more and more unixy enviornment on the windows, I eventually switched to macOS.
Apart from the obvious hack-value, I can't quite imagine even pretend use-case, with some 486 era machine, you would be limited by memory quite quickly!
Hmm I wonder how stable it is.. It cannot render correctly Window control buttons (Minimize, Maximize, Close). If it fails on such basic task, I wonder where it crashes...
Little late but would this have actually allowed running early Linux under Windows when Windows 95 came out in the 90s? I remember only dual booting being available at that time.
Everytime I see something like this, I'm like, how in the hell did they learn and then figure this out? Congrats on this!!!! I will definitely have to play with this for some of that sweet nostalga.
If I can get this to work (haven't tried yet) it directly solves a problem I have right now this week right here in 2026, 30 years after Windows 95 was even a thing.
Yes, I have weird problems. I get to look after some very weird shit.
The core of the software is a subsystem, specifically a Windows subsystem; you're not running this subsystem on macOS or FreeBSD.
The "for Linux" is added because it's a subsystem for Linux applications (originally not leveraging a VM).
Microsoft also had the "Microsoft POSIX subsystem" (1993) and "Windows Services for UNIX" (1999) which were built on the "Subsystem for Unix-based Applications" (rather than "Unix-based Application Subsystem"). That chain of subsystems died at the end of Windows 8, though.
There are many reasons not to put "Linux" in front, but the naming is consistent with Microsoft's naming inconsistencies. It's not the first time they used "subsystem for" and it's not the first time they used "Windows x for y" either.
The naming is ambiguous, you could interpret the Windows subsystem for Linux as a subsystem of Linux (if it had such a thing) that runs Windows, or as a Windows subsystem for use with Linux. Swapping the order doesn't change that.
In other languages, the difference would be clearer.
Other people already answered but windows was just another personality on the original idea that cutler had for WNT. It just took a while for it to get implemented as a linux
To reciprocate the naming of Wine, maybe it could have been named Line. Also, both have this positive clang, being associated with "having a good time".
I always have the same problem myself. Same as I had with version naming of old programs like "Microsoft Word for Windows 2.0" instead of the easier "Microsoft Word 2.0 for Windows".
Wait until you find IE was released for Unix, using some Win32 shims. And... die hard Unix sysadmin ran it under FVWM and compared to Netscape wasn't half bad.
Both propietary, but sadly NScape didn't open Mozilla yet, and the rest of the alternatives such as Arena/Amaya coudn't compete with 'modern' CSS features and the like.
Oddly enough, I could kind of use this right now. I have some software which used SCSI (Adaptec WNASPI32.dll) calls to administer a device over the SCSI bus .. would this Subsystem be usable for that, or does it still require I build a WNASP32.dll shim to do translation?
So, you have Windows software. This "Windows 9x Subsystem for Linux" just boots Windows 95. I don't know what you would use the Linux part for. Care to explain more what you want to do?
If you want to run your windows software in Linux, you could try Wine. Wine seems to have support for WNASPI so it's possible your software would just work. (You might have to run Wine as root I guess, to get access to the SCSI devices.)
If Wine doesn't work, Windows in QEMU with PCI passthrough to the SCSI controller might have better chances to work.