I can also conceptually appreciate the input/output/error piece, although I bet it'll make more sense when I find a use case for it eventually. Thanks!

[–] ultra@feddit.ro 3 points 2 years ago (1 children)

Do I also understand right that file extensions aren't anything more than the file name?

For the kernel, yeah. A lot of apps use them, though, but mostly for determining whet kind of text plain text files are.

But files have some "mode bits" at the start, hwich tell the kernel if they're executable, and whether they should always have root (admin) perms.

Speaking of root, that's the user with full perms. Root can access any file on the system, and can basically do anything. Root is also known as the superuser. When you use sudo, you run the program as root (it stands for "Super User DO").

Thanks!

You're very welcome!

[–] AVincentInSpace@pawb.social 2 points 2 years ago* (last edited 2 years ago)

and whether they should always have root (admin) perms.

Not quite! The setuid bit means the file will be run as its owner, not necessarily as root. The most common use for this (which is used by sudo) is to have the file owned by root and executable by everyone, so that when anyone runs it it will run as root, but you can also use it to have a program always run as any user (thus limiting what it's allowed to do). There's also a setgid bit so it will be run as its owning group, which is less frequently used. Fun fact!