Cherishing all nuggets of knowledge.

"Everything is a file" is what made me start understanding linux few years ago and from there it got easier to use with each new concept.

Still this was really revolutionary to me when I first heard it. Made a bunch of things just click.

420 points · 42 comments · view on lemmy.world

42 Comments

MrChewy@lemmy.world · 31 pts · 221d (14 replies)

I may be dumb, been on linux too long or a combination of both. But what other way is there, does windows work differently? (regarding that)

rtxn@lemmy.world · 68 pts · 221d (2 replies)

"Everything is a file" means that many of the system's components are represented as abstractions in the filesystem. It's simply an API that allows reading from and writing to it by integrating into the hierarchical file structure.

If you take a look inside /sys, you will find a fuckton of files, but they don't represent data stored on a mass storage medium. Instead, the directory contains a mounted sysfs filesystem that contains file-like representations of various parts and properties of the system. For example, you can read them like a file by running cat /sys/block/sda/queue/rotational to check if the sda block device is a spinning disk (1) or solid-state storage (0). Or you can write to them like a file by running echo 1 > /sys/block/sda/devices/delete to command sda's driver to detach the device. Similarly, /proc contains a mounted procfs filesystem that presents information about running processes as file-like entries; /dev contains a mounted devfs that points to various devices; and /tmp and /run contain tmpfs mounts for temporary storage in volatile memory (RAM or swap).

Windows uses various other APIs (like the Component Object Model and others) to accomplish the same that are not necessarily tied into the filesystem.

TimeSquirrel@kbin.melroy.org · 29 pts · 221d (1 reply)

Exactly the same concept as memory-mapped hardware I/O, or virtual file system drivers. Makes it so you don't have to think too much about implementation details and uses a common interface that's already there.

ByteJunk@lemmy.world · 13 pts · 220d

Sensible, yes.

But this is alien tech in windows land, if you're reading some device status or something, you need a special app for that.

witty_username@feddit.nl · 15 pts · 221d (10 replies)
[ removed ]
Successful_Try543@feddit.org · 37 pts · 221d (4 replies)

Also, in unixoid systems, devices are files too.

drosophila@lemmy.blahaj.zone · 47 pts · 221d (3 replies)

Anyone interested in this concept should take a look at plan9. Everything is even more of a file there.

Taking a screenshot, for example, can be done with:

cat /dev/screen | topng > screenshot.png

That combined with the way that parent processes can alter their children's view of the filesystem namespace allows for extremely elegant abstractions. For example, every program just tries to write directly to screen or audio, but the desktop environment redirects their writes to the relevant servers. Which means that, in the absence of those servers, those same programs can run just fine and don't care whether they're being multiplexed or not. That also means that the plan9 userspace can be nested inside itself just using the normal mechanisms of how the OS works (that is, without a special tool like Docker).

Peruvian_Skies@sh.itjust.works · 11 pts · 221d

This is very interesting.

2deck@lemmy.world · 6 pts · 220d

👀 What kind of voodoo...

ByteJunk@lemmy.world · 6 pts · 220d

That is indeed seductive.

Zagorath@aussie.zone · 15 pts · 221d (2 replies)

That might be part of it, but I was thinking it was more how things we don't think of as files, like sockets, are accessed with a file descriptor.

pewpew@feddit.it · 11 pts · 221d

Also hardware is treated like a file in /dev

Badabinski@kbin.earth · 8 pts · 221d

Hell, Bash provides filesystem-based sockets in /dev/tcp, so a tcp connection can almost be like Unix sockets or anything else.

I always found it weird that it was specifically provided by Bash...

unknownuserunknownlocation@kbin.earth · 3 pts · 221d (1 reply)

Mind you, the registry is also just a couple of files that are shown to the user as "the registry". IIRC, on Windows, go into the user account's root folder, and you'll have NTUSER.dat. That's the HKCU hive for that user.

Peruvian_Skies@sh.itjust.works · 7 pts · 221d

And that's precisely the difference. In both cases the configuration is data stored on disk but Linux presents it as files while Windows presents it as a registry tree. In Windows, you're not supposed to edit the registry by interacting with NTUSER.dat as a file.

Dialectical_Specialist@quokk.au · 17 pts · 220d (1 reply)

wait til you gentoo and find out even folders themselves are files(as far as the machine interprets it anyway)

87Six@lemmy.zip · 9 pts · 220d

Isn't that.. Normal tho?

janet_catcus@lemmy.blahaj.zone · 15 pts · 221d (12 replies)

it's all fun and games until you want to use your mouse and keyboard inputs on another machine and also view the other machines screen contents. then all of a sudden stuff stops being a file. quaint.

if only there was a way to share resources over a network...

FooBarrington@lemmy.world · 13 pts · 221d (2 replies)

Why aren't the Linux devs just using SMB to forward the mouse and keyboard files? Are they stupid?

mumblerfish@lemmy.world · 26 pts · 221d

What do you mean? This

remoteuser@server$ nc -l -p 4444 > /dev/input/event0


localuser@laptop$ cat /dev/input/event0 | nc server 4444

doesn't work?

janet_catcus@lemmy.blahaj.zone · 4 pts · 220d

eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeew scoots faaaar away from you actually when writing the prior comment, i was thinking about the ease that is doing what i described on plan9, there everything is in fact a file, which you can simply mount via the 9p protocol

what mumblerfish suggests looks interesting and i would have to read some the man page of "nc", i suppose...

FauxLiving@lemmy.world · 7 pts · 220d (8 replies)

I've figured out how to control computers remotely and I'll share the script:

Client:

#!/bin/bash
PASSWORD="your_password_here"
sshpass -p "$PASSWORD" scp /dev/stdin user@server:/path/to/cmd.txt <<< "$1"

Server:

#!/bin/bash
while true; do
    while IFS= read -r line; do
        eval "$line"
    done < "cmd.txt"
    > "cmd.txt"
done

Just chmod 777 both files and run as root, ez.

jim3692@discuss.online · 4 pts · 220d (7 replies)

What's the difference between this and the classic "ssh user@server" ?

FauxLiving@lemmy.world · 3 pts · 219d (6 replies)

we're fans of internet horror memes and being loud in libraries. so we love scp and hate ssh

jim3692@discuss.online · 3 pts · 219d (5 replies)

😐

FauxLiving@lemmy.world · 2 pts · 219d

Don't judge me

caseyweederman@lemmy.ca · 2 pts · 219d (3 replies)

In case you were genuinely curious: the above humorous example bypasses very many very good safety precautions and conveniences.
When you boil everything down, one element stands out: the s in scp stands for ssh, so you are in fact still using ssh, just with several hoops bolted on.

FauxLiving@lemmy.world · 2 pts · 218d (2 replies)

the above humorous example bypasses very many very good safety precautions and conveniences.

I was taught in school that security and convenience are diametrically opposed, so if you can find any way of making this less secure/more convenient I'd be happy to deploy it to the entire credit union.

caseyweederman@lemmy.ca · 2 pts · 218d

Just make the entire filesystem 777. And bypass the ssh warning when id_rsa is too permissible.

Korhaka@sopuli.xyz · 8 pts · 221d (10 replies)

I am curious what you mean by everything is a file... What else would it be?

JayDee@lemmy.sdf.org · 17 pts · 221d

It's more a philosophy for Unix systems. When we say that "everything is a file", we're saying that even devices should show up on the filesystem (/dev), even network ports should show up on the filesystem, even processes should show up on the filesystem(/proc), etc... and that is as opposed to having a different system abstraction handle those functions instead.

Of course when you look deeper into it, linux does not explicitly follow that rule, it more just adheres to it. It's more a guideline than an explicit statement of fact

verstra@programming.dev · 13 pts · 221d (2 replies)

It could be a process, which you can talk to only via an IPC call. For example, dbus

gandalf_der_12te@discuss.tchncs.de · 3 pts · 220d (1 reply)

can't you somehow do IPC via filesystem-based sockets in linux too?

verstra@programming.dev · 3 pts · 219d

Yea, but socket is not a file. Maybe if you stretch the definition.

Well in any case, when people say that linux is great because everything is a file, they either mean that:

  • they can edit configuration of most things with a text editor, or that
  • in bash (and other shells) it is easy to work with byte streams, piping them from one process to another and compose complex behaviour from simple commands.
Zagorath@aussie.zone · 5 pts · 221d (5 replies)

Yeah I'm interested in how that works too.

I've recently been looking at the Nextcloud "all in one" Docker image. It works by mounting the docker.sock file into the master container, which allows that container to stand up a whole bunch of other containers on your machine.

How would that work on Windows, if the Docker socket isn't a file handle?

Peruvian_Skies@sh.itjust.works · 4 pts · 221d (3 replies)

Docker Desktop handles the abstraction in Windows and MacOS. The container thinks it mounted a file.

Zagorath@aussie.zone · 3 pts · 221d (2 replies)

and MacOS

Oh that's interesting. I wonder why they do it that way, considering macOS is a Unix OS.

BreadstickNinja@lemmy.world · 2 pts · 220d

I dunno, but it's a pain. Hiding low-level components from the user to make it more user-friendly.

I have an old 2014 macbook with a busted GPU temp sensor. The Mac firmware assumes the worst - that the computer is dangerously overheated - and therefore throttles back the CPU by 80% and runs the fans at full blast.

Fixing it on Mac required a number of third-party tools and flashing a custom firmware. I then installed Linux on the device - about ten lines of script that read from the working temp sensor on the CPU die and write a scaled value to /sys/ in response.

So much flippin easier on Linux.

Peruvian_Skies@sh.itjust.works · 2 pts · 220d

I just said that Docker Desktop handles it. I've never used a Mac so I don't know for sure what's going on under the hood there but I imagine that everything they can do the same between Mac and Linux, they do. It's easier that way.

MCHEVA4EVA@lemmy.world · 2 pts · 220d

AIO is a fun one to setup. I found it much easier with portainer. The thing that always catches me with Docker is the permissions after it's setup. I had nextcloud up for a week I could access my external hdd over Webdav and nothing else haha.

Fedop@slrpnk.net · 5 pts · 219d

Just in case, I have to share this great explanation of the term "everything is a file": https://unix.stackexchange.com/questions/141016/a-laymans-explanation-for-everything-is-a-file-what-differs-from-windows#141020

This really helped clear things up for me, the main idea is that everything is represented by the filesystem, so you can use the same file-manipulation tools on a ton of systems.

MrSoup@lemmy.zip · 3 pts · 220d

Until you discover dbus