Introducing tmux-rs
195 comments
·July 3, 2025mbreese
tombert
Completely agree. Not every project has to be out there to change the world.
I recently rewrote `fzf` [1] in Rust. Did I have any particular reason to do so? No, not really, regular `fzf` is fine, but I thought it would be a fun excuse to learn how fuzzy search algorithms work and how to exploit the channels in Rust. It was fun. There's no question that regular fzf is better but that wasn't the point, the point was to play with stuff and learn.
carlmr
Nice, I do think fzf is a really good candidate for something that could be better if written in Rust. The fzy[1] C-rewrite is really fast, but I couldn't get it to give me as useful results when searching bash history.
[1] jhawthorn/fzy: :mag: A simple, fast fuzzy finder for the terminal https://share.google/TBp3pVaFngBTfaFyO
tombert
Yeah, I think Rust makes some sense, and I do think I've done a few clever things like getting a linear-time "sort" by exploiting the fact that there's a discrete and finite number of "scores" [1], and avoiding copies by taking the indexed values and explicitly moving them into the source channel to avoid extra copies [2].
Someone smarter than me who is more familiar with TUI programming could almost certainly augment and improve what I wrote; I worked on it for as long as it was interesting to me. I use it for my home-built program launcher thing Sway, though most people would probably get better results with real fzf.
[1] https://github.com/Tombert/rs-fzf-clone/blob/main/src/helper... [2] https://github.com/Tombert/rs-fzf-clone/blob/main/src/proces...
planet36
"Gardening is the handiest excuse for being a philosopher." - Ray Bradbury, Dandelion Wine
1vuio0pswjnm7
"We don't necessarily need a reason to build new things."
But tmux isn't new
Is a reason necessarily needed to rewrite software in other languages
fragmede
GNU screen would like a word.
godelski
Honestly, I often hate how people ask "why?", and don't understand how "for fun" is a legitimate answer. I get it for work or other things, but hobbies? We do lots of things for fun! Humans were born to play, just like every other animal. It's how we learn and explore the world around us.
And frankly, to quote Knuth
> In fact what I would like to see is thousands of computer scientists let loose to do whatever they want. That's what really advances the field.
Arisaka1
I still believe that my #1 think that stunted my growth as a junior SWE was overthinking my personal projects and languages to use for them, instead of just building whatever I felt it's interesting or intriguing to build.
godelski
It's always hard to tell. But have you considered you might be measuring the wrong way?
To me it sounds like you learned a real important lesson one that some people never seem to learn.
I think one of the most beneficial aspects of doing things "just because" is these other skills or information you get along the way. It is very easy to miss all of this progress if you're too focused on the progress of the more tangible things. But that doesn't make any of that not progress. So don't put yourself down for that, because I'm sure you learned a lot. The only reason you can look back and see a better way is because you made that progress and learned those lessons. These are things mentors can usually help you get through faster but not everyone has a mentor nor access to one. But don't undermine your own progress just because you didn't finish projects or because you did things differently than others
ku1ik
Same here!
serial_dev
Asking “why” can still be a legitimate question, and “for fun” can also be a legitimate answer.
I treat projects differently if they want to launch a product, they want to replace an established open source tool, done for fun for themselves, or if it’s a hobby project.
charcircuit
There is more than 1 way to have fun. Some ways of having fun will produce more value to other people than others.
null
cultofmetatron
> Like gardening, but with more segfaults.
interesting, I'm new to rust. what are you doing that necessitates using unsafe?
jeroenhd
A lot of things that C will let you do (even if you enter the realm of undefined behaviour) will simply not compile to C. As the author states, there are semantic differences between pointers and Rust's references.
C pointers can have as many owners as you want, may be subjected to mathematical operations, and can be cast to any type without even an error message. The compiler will just assume you know what you're doing. If you enable enough compiler warnings, it might warn you, but C compilers don't generate a lot of those by default.
Rust will let you only generate one mutable (exclusive) reference at a time. This means straight C to Rust ports simply don't compile.
By switching to pointers, which work pretty much like their C equivalent, you can port the code much easier, but you do of course lose the benefits of Rust's safety mechanisms, because most pointer operations throw away all the safety guarantee that Rust provides.
zozbot234
> Rust will let you only generate one mutable (exclusive) reference at a time.
Safe Rust includes many forms of shared mutability, including Cell<> which is perhaps the closest comparison to typical patterns in C code.
SoftTalker
So what is the advantage of an unsafe Rust implementation? Just to have done it?
krater23
Hmm...I like when the compiler don't steps in my way and assumes that I know what I'm doing. Thats the reason why I don't like Rust. But when you like it, have fun!
tshaddox
I suspect it's vastly easier to port C to unsafe Rust than to safe Rust.
upmind
I found out that quite funny, I wonder how many hours he spent on this. It seems extremely monotonous haha
ziml77
Sometimes that's exactly what one needs. As long as there's not forced schedule for the work and you can do it when you want and at the pace that you want, it can feel good.
phkahler
I think knitting looks monotonous, but I can see the appeal.
null
rauli_
Not every code project needs to turn out to be world changing. Experiments like this sometimes produce excellent results.
ethagnawl
This announcement has my attention.
I've been working on a Rust-based tmux session manager called rmuxinator (i.e. tmuxinator clone) for a few years now. It (mostly) works and been slow going because ... life but I've recently picked it back up to fix some bugs. One of the last new features I'd added was the ability to use rmuxinator as a library in other Rust programs. I'd like to try forking tmux-rs, adding rmuxinator as a dependency and seeing if it would ... just work as a way to start sessions using per-project config files. I'm definitely not advocating for adding rmuxinator upstream but it would be very nice to have this sort of session templating baked into the "terminal multiplexer" itself.
The other interesting possibility I could foresee is doing things the other way around and having rmuxinator use tmux-rs as a library in order to setup and manage sessions instead of just dumping out shell commands -- which is fraught with edge cases. (Not sure if this is currently possible with tmux-rs, though.)
Once I wrap up the bugfixes I'm currently working on, I may fork this project and give one or both of the above a try.
Regardless, nice work by richardscollin!
pizlonator
I just ported tmux to Fil-C in less than an hour (that included porting libevent and gettings its test suite to pass).
Works great and it's totally memory safe
uecker
I like this post, one can learn a lot.
It seems automatically translating Rust to C is not a very good idea: "I threw away all of the C2Rust output and decided I would translate all of the files into Rust manually from C.". Neither seems doing it manually: "I introduced many bugs while translating the code. I’d like to share the process of discovering and fixing a couple." Or using AI: "That’s because when using cursor to translate the code it would still occasionally insert bugs, just like me. So, I spent as much time reviewing the generated code as it would have taken me to write it myself."
As a hobby project, all power to you. But otherwise, maybe better not rewrite working code....
perching_aix
This reminded me of no-code: https://github.com/kelseyhightower/nocode
antonvs
> But otherwise, maybe better not rewrite working code....
Except that the eventual result allows for extension and improvements in a memory-safe language.
uecker
There seems to be some rather irrational obsession about this.
antonvs
Things can seem irrational when you don't understand them.
Another comment in this thread hoped for "a brand new bulletproof tmux-resurrect". The reason there's a desire for such things is closely related to the limitations of non-trivial programs written in C.
They're harder to extend without bugs, harder for new team members to understand, and so on.
The "irrational obsession" has to do with advancing the state of the art beyond a primitive high-level assembler that was developed in the 1970s.
wat10000
It comes from the fact that nearly every useful program written in C has multiple security vulnerabilities just waiting to be found. In the unlikely event that you have a codebase that's free of them, you risk introducing one with any significant change.
hnlmorg
tmux doesn’t really gain anything from memory safety because:
1. anything running in tmux already has execution rights and typically for the same user as tmux anyway.
2. Anyone who wanted to exploit tmux could just run ‘tmux -C’ and automatically get access to literally every interaction within tmux.
3. The software itself is already damn stable. I've never had it crash.
If you’re worried about someone exploiting your terminal then tmux is a terrible option, irrespective of whether it’s with written in C or Rust. And I say this as someone who absolutely loves tmux and uses it every day.
[edit]
And if you're worried about non-security related bugs affecting UX, then a rewrite in any language, regardless of the language, is a worse solution if your application has already been battle-tested for close to two decades. You're much better off creating something entirely new instead of porting code from one language to another because at least then you have new ideas instead of the same application but with new bugs in different places.
I don't say this because of some bias that Rust fanboys will assume I have. I love memory safe languages and think Rust is a great option for new projects. The point I'm making here is that a rewrite doesn't gain much for tmux SPECIFICALLY because tmux is already extremely stable.
remram
You forget that tmux is a terminal emulator. Trusted programs can have untrusted/attacker-controlled terminal output. If the program running inside tmux (e.g. cat, curl -s, weechat) can output malformed unicode or escape commands that trigger crashes or code execution, it is actually a huge problem.
legobmw99
There are reasons to be worried about additional safety beyond just security. My first thought when reading the article was it would be a huge bummer if a bug in tmux brought down a long-running or particularly stateful session. Of course, I’ve never encountered such a thing in my own usage, but if you could make it less likely that alone seems like a value add
antonvs
Any program gains from memory safety. Memory safety is not just about security. It's about eliminating an entire class of bugs - buffer overflows, null pointer errors, use-after-free, the list goes on. They just so happen to be the kind of bugs that also tend to have serious security consequences.
I honestly don't get this relentless defense of 1970s-style programming. Do you think C is the pinnacle of programming language design? No? Then what's your point, exactly?
greenavocado
This is funny, but unfortunately .NET went all in on the AI coding assistant kool-aid.
https://github.com/dotnet/runtime/pull/115762
https://github.com/dotnet/runtime/pull/115743
tacker2000
Wow, so this MS dev is trying out Copilot on the dotnet repo and doesnt even configure it correctly beforehand?
Or was that comment just a cop-out because Copilot’s results were complete nonsense?
tekawade
I love this. I also want to dabble into loving things to rust!
Here I want to call out zellij. Zellij is rust based terminal multiplexer.
I am user not creator. I love everything rust and finding and migrating to rust based solutions where feasible.
gmoque
I love the attitude on this project and most of the comments are supportive. While rewriting a mature application to another language always sounds like a bad idea, there are so many learnings along the way. It's not about the end it's about the process.
Given the traction you got here and the advancements in AI, I'm sure this can become a very attractive hobby project for Rust beginners, there's probably a lot of easy bugs to fix. Fixing bugs, adding new features, and optimizing the code is all you need.
Here's an idea to get the ball rolling: Create a scratch buffer for Gemini CLI (or your favorite LLM) and enable it to interact with the various windows and panes of the tmux session.
Here's my use case, I use synchronized panes to send the commands into multiple servers, but some commands sometimes fail for various reasons. What if I can just ask the AI to send a series of commands and react based on the output and adjust along the way. It's like a dynamically generated custom shell script on the fly.
tialaramex
Coincidentally I was just watching this, "Oxidise Your Command Line"
https://www.youtube.com/watch?v=rWMQ-g2QDsI
Some of that video is about stuff you have no use for if you're not a Rust developer, but, some of it is things that would be just as useful to anybody who is comfortable with, as it says, a command line interface.
someperson
Surely improvements be made to c2rust to reduce the cited information loss with constant naming, to reduce the initial conversion burden?
kevincox
Yeah, this seems like a huge missing feature for C2Rust. IIUC the main idea is to serve as a base for then porting to idiomatic Rust. But if you lose all of the constants that is a huge productivity loss.
dataking
Indeed. We had experimental support for preserving (some) constants but it fell by the wayside. We're bringing it back in the coming months.
rthnbgrredf
This seems like an excellent future use case for a fully automated process by a large language model that translates a non-trivial C codebase to Safe Rust in under an hour with high accuracy. However, as the author noted, even after some attempts with Cursor at the end of development, the tool wasn't able to accelerate the translation effectively (in mid-2025). So while the potential is promising, it appears we're still some way off.
gavmor
These folks[0] are doing it, possibly via "codemods"[1], which utilize ASTs.
0. https://codemod.com/ 1. https://martinfowler.com/articles/codemods-api-refactoring.h...
keybored
> This seems like an excellent future use case for a fully automated process by a large language model that translates a non-trivial C codebase to Safe Rust in under an hour with high accuracy.
That’s specific.
xvilka
Nice, hope it will become cleaner code in time. I tried zellij multiple times but despite years of development it still misses many things tmux provides. Inability to show/hide status bar[1] is the most annoying.
imbnwa
You can't rebind key maps to its session manager plugin, making it a no-go since I bind the same key that the plugin uses to select a directory or something. Thus, I can't create new sessions through it, have to do it from the command line.
teekert
Nice, I like tmux, I use it daily, I live in it. I hope this version makes it easier to just scroll with the scroll wheel or ctrl-page-up/down, or ctrl tab through your panes, or just show the whole unconcatenated title in the bottom left ;)
Sorry I know this is not the place to complain, but it would be so nice!
antonvs
I use byobu which is basically an opinionated distribution of tmux. Scroll wheel works fine, as does Alt-PgUp/PgDn.
Ctrl-Tab probably won't work because terminals tend not to recognize it as different from Tab. But you might be able to bind Alt-Tab or some other such combo to cycle through panes in the tmux config. It should just be a one-liner.
psyclobe
Oh neat!!
jayknight
For me scroll wheel just works. The other stuff wouldn't be hard to configure with `bind-key`. I use ctrl-space to cycle through panes in a window:
bind-key -n C-Space select-pane -t +1
0x457
You might like zellij more than tmux.
df0b9f169d54
tmux has been used a lot of memory on my system, especially when scrolling buffer is large enough (I often have > 10k lines of things ).
I have often executed `pkill -9 tmux` and saved my day. I hope the rust version can help a bit here?
01HNNWZ0MV43FF
How much is a lot? Even 10,000 lines of text should be on the order of megabytes, right?
throwaway290
Tmux has configurable scrollback buffer size, maybe set-option -g history-limit something-smaller in your config?
downrightmike
Let us know
> You might be asking: why did you rewrite tmux in Rust? And yeah, I don’t really have a good reason. It’s a hobby project. Like gardening, but with more segfaults.
I love this attitude. We don’t necessarily need a reason to build new things. Who knows what will come out of a hobby project. Thanks to the author for the great write up!
Also, my gardening is full of segfaults, coding a new project is definitely safer to my yard.