What would be considered "proficiency in Linux"?

How about you wait until you land an interview first, before you worry about job requirements.

I had to apply to over 300 jobs before I landed an interview, so chances are they won't even look at your resume. Even with a great resume, it's extremely difficult to land a job in today's environment.

I don't mean to sound negative, only realistic. Your main focus right now should be rapid firing off as many applications as you can, and nothing else. Worry about the job requirements after you get past the application stage.

Apply and see. Worst case is you learn something.

My interviews for linux-related roles were basically, "how do you change directories? What does ls do? How do you edit a file?" (Last one was trickily open-ended to also see what my preferred editor is). I'm not even sure they asked where log files are typically stored.

As for what to put on a resume, just say that you run a home lab or something.

Gonna echo the others here:

1. Apply anyway.
2. If you can do work in Linux without handholding for general tasks, you're "proficient."

In my experience, imposter syndrome prevents the best candidates from applying because they weed themselves out.

To be considered proficient in Linux you need to have contributed to the Linux kernel AND be able to exit from vim (without just rebooting the machine).

For that kind of description, I would expect proficiency to mean that you can perform your job on a Linux machine with no training. Can you open programs, deal with file structures, and overall not need to call IT for basic issues.

You're over thinking it. There are no standards. There is no meaning. You're over qualified. Just apply.

In this kind of job, I'd guess they hope for someone who's done VFX work on Linux before, but if you know about cd and ls, you probably already fulfill their expectations.

If you didn't have any experience, that likely wouldn't be a deal breaker, it would just be one more thing where they need to get you up to speed.
Well, and if you were a Linux crack, able to support others in your team and dish out scripts for automating menial tasks, that would be a bonus.

But yeah, you having even used Linux before probably makes you one of their, if not the, most qualified applicant in this regard, so I really wouldn't worry about it.

It wouldn't surprise me if it's interpreted similarly as "Microsoft Word proficiency" in recruiter speak, which really means, are you able to type a letter in it and hit the print button.

The most I would expect is maybe finding your way in a shell, to run a render on a beefy server over SSH or something like that. Some familiarity and the will to learn is probably good enough.

I mean, it's the hiring company's job to vet you, not yours. The requirements are to provide you with some guidelines to avoid having you waste time. If you think you can do the job, I'd go ahead and apply. They're gonna try and get the best fit candidate from those that apply, regardless. If they had more-specific requirements, like knowledge of some specific software package, they could have included it in the job requirements. I wouldn't over-analyze it.

If you're concerned about it, every place I've ever interviewed at has had someone who is supposed to take questions from the candidate at the end of the interview. You can probably ask them there if there's a specific set of things on Linux that it'd be useful to know.

EDIT: And as someone who has done plenty of software development work, if someone just put down "Linux proficiency" and expected it to be interpreted without additional context as having some specific background in software development, I'd be surprised. But my larger point is that I don't think that I'd fret about it.

In the context of VFX/3D art jobs that you've mentioned, it can be that the ability to do everything on a Linux system. What that entails is beyond me. I'm far removed from the area.

Taking the stab all the same.

At a high level, can you get the software working on Linux system? Can you get the codecs and whatnot installed and working? Can you get the data to be processed prepared for working in the environment? Can you convert the processed data to the format that is friendlier for consumption on a wide range of platforms? Are some questions that pop to the top of the mind. Basically if you can run a non trivial part of the business without making a fuss, I'd consider you proficient. What you can and cannot do outside of this scope is, well, none of my business.

In this context, I imagine it means you're not going to freak out when you see something that isn't Windows or Mac OS. Can you move things around with the file manager? Find the wifi settings? Get files off the external hard drive you just plugged in? That's probably sufficient.

Of course there are dozens of possible file managers and wifi widgets. They could be using any of many distributions with a near infinite combination of software. I'm proficient at Linux by nearly any definition, but I haven't checked out recent versions of desktop environments other than the one I use regularly. As long as you can figure out basic computer stuff on something that looks a little different from what you're used to, you should be fine.

Making the webcam work

If companies can lie to you then you can lie to companies

Are you able to do the same stuff relative to your job on linux as you can with win or mac?

Being able to read a man page, understanding the syntax and how to move back up the page (b is half page back).

Just based on what you wrote and what I know of linux, I'd say knowledge of the filesystem, installation and troubleshooting process, gpu drivers and troubleshooting them, getting different setups, both hardware and software going and keeping them in good working condition in a workplace environment where long downtimes arent acceptable like they might be for a hobbyist.

Of course that will probably include good knowledge of the terminal and what it can do, basic bash skills. Maybe also knowledge in enterprise linux distros.

But then again, job ads are usually written by people who have the least professional skill in the posted job and often only view things from their perspective which means they might say proficient because you're supposed to not be scared or a noob when using linux at work.

Be able to install and configure, be comfortable with the command line, know how the package manager works, if there's specific software you need to use, know how to launch it and how it works.

My personal arbitrary qualifier is understanding what every folder in the root directory is for and most of the contents.

But I think for a job it's just you can use the operating system without asking for help at all/too often.