Let me start off by saying: If you just want to have a working system to do your thing with minimal effort, Slackware isn't for you (anymore).
Running Slackware today is like being gifted a Ford Model T by a weird, bearded museum curator, and then finding out that after some minor modifications and learning how to drive it, you can keep up with any modern car on the road. Only it has no ABS, AC, power steering, starter motor, crumple zones, airbags or seatbelts.
Most people who still run it (by any realistic estimate, fewer than 10000 people in the world now) have been running it since the 90's and follow the advice not to change a running system to the letter. So why should anyone who hasn't studied CompSci in Berkeley in the 90's try it today?
First of all, the most widely known criticism (it has no dependency resolution) is a bit of a misunderstanding. Slackware is different. The recommended installation method is a full installation, which means you install everything in the repository up front. That way, all dependencies are already resolved. And you have a system you can use equally well on a desktop or server. It uses 20GB but disk space is essentially free now.
What if you need something that isn't in the repo? Well, do whatever the fuck you want. Use Slackbuilds, which aren't officially supported but endorsed by Slackware's dev. Use Sbopkg, a helper script with dependency resolution very much like Arch's AUR helpers. Use the repos of sister distros like SalixOS that include dependency resolution. Install RPM packages. Install Flatpaks. Unpack tarballs wherever you want them. Go the old school way of compiling from source and administering your own system yourself. Slackware doesn't get in the way of whatever you want to do, cause there's nothing there to get in the way.
It's the most KISS distro that exists. It's the most stable one, too. Any distro-specific knowledge you acquire will stay valid for decades cause the distro hardly ever changes. It's also the closest to "Vanilla Linux" you can get. Cause there really isn't anything there except for patched, stable upstream software and a couple of bash scripts.
Just be mindful of the fact that Slackware is different (because the Linux ecosystem as a whole has moved on from its roots).
One example:
Up-to-date Slackware documentation isn't on Google, it's in text files written by the guy who maintained the distro for 31 years, which come preinstalled with your system. Or on linuxquestions.org, where the same guy posts, asks for input from users, and answers questions regularly.
It's still a competent system, if you have the time and inclination to make it work. And it's a blast from the past, where computing was about collaborating with like-minded freaks on a personal level. And I love that.
The biggest reason I use Slackware personally is that it's the only distro I'd consider a "full system" out of the box. What that means, is that I install it, and I don't really install much outside of the repos.
For example, the kde set comes with pretty much every KDE app. I do mean all of them. With other distros, I either have to go hunting for what packages are named what in the repos and spend hours getting everything setup and installed. While on Slackware, I pick the partitions, install, and I have a full desktop with everything I could possibly need.
Some would say "Oh, but that would take a lot of disk space.", and funny thing about that, is with BTRFS compressio enabled. A full install of Slackware is only 4gb =P
"If you want to know how Linux works, ask a Slackware user."
I've mentioned this a lot lately, but I used Slackware from the late 90s (3.x days) until about 2009 on my desktop and laptop, and about 2017 on my server. I just got tired of dealing with dependencies and switched to Debian (all three run Debian now). I had the CD subscription and would automatically receive the latest version about twice a year.
Patrick Volkerding (if my memory is accurate) has my utmost respect, and I do feel a little bad about abandoning it, but I just didn't have the time to deal with it any more.
I've used slackware more or less exclusively since the late 90s. It's been my daily driver since I deleted my windows XP partition some time in the early 00s. It's really all I know. Sure, I can find may way around a .deb based system when I have to. I'm also likely to apt install something, say yes to 50 dependencies, brick my system and have no idea what did it.
I love to tinker, and I love to learn. There's no shortage of either in Slackware, and that's why it's not for everyone. And I don't mean that in an "i use arch btw" way. I'm an intermediate user at best. I ask for help way more than I provide help. Lucky for me I've made some good friends in the Slackware community over the years.
If you hate bloat you like Slackware. It doesn't assume anything about how you want to use your computer, so it's more painful for a lot of folks. Other distros will try to do things for you and will ultimately end up doing something someone doesn't want. With Slackware you learn a lot and you get a rock-solid system that will do whatever you like, but you have to be willing to manage it.
Late reply, but I suppose you're correct; I think the option to choose what to install, the lack of pre-created desktop stuff ("home/$username/Videos" for example) and the requirement that you handle software that isn't in the base install all make a Slackware installation less bloated than most. Maybe not at install time, but over the life of the install you end up with less garbage IMHO.
Not all distros need to appeal to the mainstream. Diversity is a good thing in and of itself. In biology, it makes ecologies more robust, and there's no reason it shouldn't do the same for a software ecology.
The day when there's no longer a place in Linux for Slackware, Gentoo, LFS, Alpine, and other independent non-mainstream distros is the day I move to BSD.
I did once try to get started with Slackware when I was a teenager. It was on a cover CD for Linux Format about twenty years ago. I never managed to get it running and gave up on Linux for a while as a result.
I'm a little perplexed as to what it exists for, to be honest.
It doesn't exist for anything really. It still exists because some people still find it worthwhile to maintain it, and some people still find it worthwhile to run it.
I think you might be interpreting my comment a little too literally. Perhaps I could instead word it as "I don't know what the appeal is - to me it doesn't seem anything other than an oddly archaic OS". What's its USP, so to speak?
I had something similar when I tried running SUSE in about 2005. Shortly after I discovered Ubuntu and found that it made package management and maintenance easy and from there I was able to start using the system to get things done. Whilst I don't currently use Linux on my personal machine, I do use it on my work machine inside WSL2, on servers at work and at home.
I've never even entertained the notion that Slackware would be something I might use - because it seems clunky for the sake of clunk. Am I missing something here? Or is the clunk the appeal, like how lots of people like really awful B-movies?
I think it's a way to get to know and learn Linux from the ground up while you install it, configure it to your taste, and fix all the little issues that pop up, a bit like Linux From Scratch. But when you're done, you have a working system you know well and that won't ever surprise you.
I remember liking how it didn't mess with the packaged software (no patches, so everything was as the author intended), same as Arch, and how clean it was... for a few hours.
It does also have third party repos such as sbopkg. This does a bunch of the movement for you when installing packages though you still need to manually install dependencies, BUT If you also add sboui which is a front end package resolution for dependencies then the process is much faster. I like the stability of Slackware, and also because its helps me get better for when I try the BSD since its very much like them as well.
That’s good Slackware, don’t you waste that Slackware.
When they dropped reiser the lug broke up mostly along Debian or gentoo lines. It was hard to switch to Debian. You just can’t freely disconnect and connect things like in Slackware. You can’t just rpm2tgz some package and see if it works.
You can’t top the level of troubleshooting knowledge gained from using that distro.
About the only thing a Slackware user can’t tell you is how the system got installed. He just hit enter a bunch of times.
Slackware gets security updates backported to its package versions, like Debian. If you run Slackware Current, it's actually just as active as Arch or Debian Sid. But for the software you install from outside of the repo, keeping it updated and secure is on you. I just use Flatpaks cause I'm a lazy Slacker.
I used nothing but Slack for about 15 years. Other distros gave me.problems, hell, I compiled Gentoo from source but was never even successful at installing some of the newbie distros like Ubuntu, but Slack was always simple and rock solid. I wasn't the best at resolving dependencies, I'd just build and install anything it said I needed. I think I've had more than one version of Python or Perl installed at a time, but it never mattered. Every few years I'd wipe everything and reinstall.
I did Linux From Scratch once. I got it to the point it was booting a kennel that supported everything I needed, had a working init (sysv), a helper script that "installed" packages (symlinked stuff to integrate them into the system) and kept "recipes" for whatever I compiled.
If I had kept going and compiled everything I needed and kept maintaining that I'm guessing it would have been pretty close to the Slackware experience, right?
It was very cool to know I can do all that and I learned a lot but if I had kept going I feel like it would have become limiting rather than empowering.
Like, it's cool to go camping and catch your food, and cook it, and sleep outdoors and to know you can survive in the wild, but I wouldn't want to have to do that every day.
UnRAID uses Slackware under the hood, I've had lots of trouble trying to use the shell and install packages and init scripts. I wish it was Debian based instead so my knowledge would transfer.
I've been using various GNU/Linux distro over the course of the last 20 years. When I started out, packages could never be too fresh and cutting edge. Nowadays I'm an admin and I administer way too many VMs. I dream of a system that I never need to update. While I know that's almost impossible if you want to be secure now might finally be the time I give slackware a try. I'm also old enough to be more curious about learning less but more in depth.