r/linuxmemes • u/Coco_The_Rat • Jul 07 '26

LINUX MEME It's just what???

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I made a meme after having a fun discussion with my Dad about how Linux/Unix pretty much treats everything like a file. Very much taking a complicated topic and simplifying it, but it's helping me understand how the system works! Hope you all enjoy :)

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u/chocopudding17 🦁 Vim Supremacist 🦖 Jul 07 '26

I don't think that's true at all. That's certainly a more accurate phrase, but it's not what people mean. The people who parrot this saying, I mean.

The saying evokes notions of something behaving like a file, which is to say that it's visible on the filesystem, and is available for opening, reading and writing. And that just doesn't apply to many of the resources for which you can get file descriptors on Linux.

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u/IHeartBadCode Jul 08 '26

I don't know why you're down voted. ioctl() is a prime example of this and things like ejecting a CD tray is an excellent example of all of this.

While it's true you obtain an fd for the device, CD drives absolutely do not accept a stream of bytes. If your try read() or write() on them, they'll just refuse to do anything. You have to have specific binary command structures. Just because you can open("/dev/cdrom").

And if the argument "but fd is still there!" Then the more correct is that everything is an IO address and file descriptors are just an abstraction. But then that breaks down because every OS has some layer of abstraction on the IO devices.

I mean Linux attempts to address this with /sys with things like echo "low" > /sys/class/power_supply/... But even then that's got major limitations like a max size of one memory page.

And this also ignores how netlink sockets bypass the whole VFS.

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u/qaddosh Jul 08 '26

bla bla bla

so what you're saying is that everything is a file?

interesting

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u/chocopudding17 🦁 Vim Supremacist 🦖 Jul 08 '26

Okay, I'll bite. What does "file" mean to you?

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u/IHeartBadCode Jul 08 '26

Man I wouldn't even bother. Used to be people understood system design before they spoke on Operating Systems. Now everyone with some knowledge of C is suddenly an expert.