Scally (Nov 17 2024 at 18:50): Scally (Nov 17 2024 at 18:50):I'm currently trying to figure out how to work with Env.exePath. However when I try to log it it shows as memfd:roc_file_descriptor (deleted). Is this a bug?
My code:
cwd = Env.exePath!
cwdStr = Path.display cwd
dbg cwdStr
Oh interesting, if I run roc foo.roc it creates a foo application in the same folder but Env.exePath is broken.
If I then run that created foo application though it works as expected. Is there any way to get Env.exePath working when running as roc foo.roc?
Brendan Hansknecht (Nov 17 2024 at 19:09):roc foo.roc runs the app from in memory. It really shouldn't actually create the foo application in the local folder at all.
Brendan Hansknecht (Nov 17 2024 at 19:10):It is meant to work with roc as a scripting language
Brendan Hansknecht (Nov 17 2024 at 19:10):That said, roc should be overwriting that path such that the executable path is foo.roc or whatever path is given to roc
Brendan Hansknecht (Nov 17 2024 at 19:10):I feel like someone recently was working on fixing that. Not sure the state though
Scally (Nov 17 2024 at 19:16):Running it as a scripting only executable was kind of what I was expecting so I was surprised the application was created but I thought it just did a compile + run operation in the background.
Overwriting the path in script-mode run seems reasonable and would work for my use-case. Good that there is awareness of that. Do you know if there is a Github issue for it or something like that?
Luke Boswell (Nov 17 2024 at 20:09):Is this the PR you're thinking of @Brendan Hansknecht https://github.com/roc-lang/roc/pull/7172
Scally (Nov 17 2024 at 20:30):If that's the one that is only for args[0]. I just checked an that is indeed the file I'd expect, although sadly not a full path.
It seems that fix has no impact on Env.exePaththough.
Luke Boswell (Nov 17 2024 at 20:34):Here is the impl in the platform https://github.com/roc-lang/basic-cli/blob/918c1dcd2a863ea336e9fa0e70fa548f7107b6f0/crates/roc_host/src/lib.rs#L432
Brendan Hansknecht (Nov 17 2024 at 20:40):Is this the PR you're thinking of Brendan Hansknecht https://github.com/roc-lang/roc/pull/7172
Yes. Thanks for finding it
Jasper Woudenberg (Nov 17 2024 at 21:10):Scally said:
If that's the one that is only for
args[0]. I just checked an that is indeed the file I'd expect, although sadly not a full path.
It seems that fix has no impact onEnv.exePaththough.
You should be able to join args[0] onto the current working directory to get a full path. I do this in a different platform and it works. args[0] is just the file you pass to roc run, so if the person running the script passed a relative path, then args[0] is a relative path.
It looks like the rust implementation of current_exe for unix is here:
https://github.com/rust-lang/rust/blob/a8e75c53d0036b5d012cbc0ee5de17f8991fe60c/library/std/src/sys/pal/unix/os.rs#L253
They look in the args list as well, but then do extra work, first searching from the CWD and then the PATH. Not sure why that would fail :thinking:.
Did you change the current working directory prior to that code running?
Jasper Woudenberg (Nov 17 2024 at 21:14):Oh, nevermind, I was looking at the wrong OS. This is linux (don't know if that's the OS you're on), and it looks at /proc/self/exe for current_exe:
https://github.com/rust-lang/rust/blob/a8e75c53d0036b5d012cbc0ee5de17f8991fe60c/library/std/src/sys/pal/unix/os.rs#L406
I don't know if we can fake /proc/self/exe in the Roc script runner to point to the Roc script rather than the compiler binary, my guess would be no. Maybe the platform shouldn't rely on Rust current_exe and instead use argv0, potentially implementing something like the cwd/PATH search code I linked above that Rust falls back on for OS-es that don't support /proc/self/exe.
Scally (Nov 17 2024 at 21:14):Jasper Woudenberg said:
You should be able to join
args[0]onto the current working directory to get a full path. I do this in a different platform and it works.args[0]is just the file you pass toroc run, so if the person running the script passed a relative path, thenargs[0]is a relative path.
That was my plan now but would be nice if I could just use exePath.
What do you mean by changing the current working director prior to that code running?
I'm running roc from a parent directory (i.e. roc src/script.roc) but inside the script are no changes in working directory.
Scally (Nov 17 2024 at 21:15):Yes, I am indeed on linux
Scally (Nov 17 2024 at 21:16):Jasper Woudenberg said:
I don't know if we can fake
/proc/self/exein the Roc script runner to point to the Roc script rather than the compiler binary, my guess would be no. Maybe the platform shouldn't rely on Rustcurrent_exeand instead useargv0, potentially implementing something like thecwd/PATHsearch code I linked above that Rust falls back on for OS-es that don't support/proc/self/exe.
That seems like a good solution if the /proc/self/exe route indeed fails when running as a script.
Jasper Woudenberg (Nov 17 2024 at 21:18)::thumbs_up: Yep, I think it'd be a good issue to create on the basic-cli repo. Happy to do it if you don't want to!
Scally (Nov 17 2024 at 21:18):Can do
Scally (Nov 17 2024 at 21:37):Issue link for reference https://github.com/roc-lang/basic-cli/issues/265
Luke Boswell (Nov 18 2024 at 00:16):@Jasper Woudenberg do you intend to look at Issue in basic-cli?
Jasper Woudenberg (Nov 18 2024 at 06:40):Yeah, though in a couple of days as I've got a busy couple of days ahead!
Luke Boswell (Nov 18 2024 at 07:19):Alg, just clarifying. No rush or anything
Last updated: Jul 26 2025 at 12:14 UTC