# Loading a library which depends on another library

**URL:** <https://discourse.julialang.org/t/loading-a-library-which-depends-on-another-library/131922>\
**Category:** General Usage\
**Tags:** question, build\
**Created:** [August 28, 2025, 10:18pm UTC](https://discourse.julialang.org/t/loading-a-library-which-depends-on-another-library/131922 "2025-08-28T22:18:46Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Chrysoberyl](https://avatars.discourse-cdn.com/v4/letter/c/ed655f/32.png) [@Chrysoberyl](https://discourse.julialang.org/u/Chrysoberyl)\
**Post date:** [August 28, 2025, 10:18pm UTC](https://discourse.julialang.org/t/loading-a-library-which-depends-on-another-library/131922/1 "2025-08-28T22:18:46Z")

</div>

I have a project that is a mixture between Julia and Lean. The Lean part builds a dynamic library at `.lake/build/lib/libPlaceholder.{dylib,so}`, which in turn depends on the system Lean installation at `~/.elan/toolchains/leanprover--lean4---v4.21.0/lib/lean/libLean_shared.{dylib,so}`.

I’m loading the library like this:

```julia
using Libdl

push!(Base.DL_LOAD_PATH, "~/.elan/toolchains/leanprover--lean4---v4.21.0/lib/lean")
push!(Base.DL_LOAD_PATH, "./.lake/build/lib")

lib = dlopen("libPlaceholder")

```

which complains that

```julia-auto
dlopen(./.lake/build/lib/libPlaceholder.dylib, 0x0001): Library not loaded: @rpath/libLake_shared.dylib
  Referenced from: <4C4C447C-5555-3144-A17F-23FAD48EFDC2> $PROJECT/.lake/build/lib/libPlaceholder.dylib (built for macOS 99.0 which is newer than running OS)
  Reason: tried: '/Users/aniva/.julia/juliaup/julia-1.11.6+0.aarch64.apple.darwin14/lib/julia/libLake_shared.dylib' (no such file), '/Users/aniva/.julia/juliaup/julia-1.11.6+0.aarch64.apple.darwin14/lib/julia/../libLake_shared.dylib' (no such file), '/Users/aniva/.julia/juliaup/julia-1.11.6+0.aarch64.apple.darwin14/lib/libLake_shared.dylib' (no such file)

```

Notably, it is not looking for the dylib in question in `~/.elan/toolchains/leanprover--lean4---v4.21.0/lib/lean`.

Is modifying `LD_LIBRARY_PATH` the only way to resolve this problem? What is the best practice for loading dynamic libraries like these?

Edit: The same code works well on Linux, but does not work on MacOS.

```sh
DYLD_LIBRARY_PATH="$(lake env printenv LEAN_SYSROOT)/lib/lean" julia src/primitive.jl

```

works for MacOS though.

---

<div class="post-metadata">

**Author:** ![cjdoris](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/cjdoris/32/213133_2.png) [@cjdoris](https://discourse.julialang.org/u/cjdoris)\
**Post date:** [August 29, 2025, 11:34am UTC](https://discourse.julialang.org/t/loading-a-library-which-depends-on-another-library/131922/2 "2025-08-29T11:34:53Z")

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I’m no expert but I think maybe if you do `dlopen("libLean_shared")` first, with the right flags, then the system remembers where this library is when it needs to load it again.

(I think the issue that you’re experiencing is that `DL_LOAD_PATH` is only used to find libraries loaded directly by `dlopen`, not ones that those load.)

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<div class="post-metadata">

**Author:** ![stevengj](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stevengj/32/71_2.png) [@stevengj](https://discourse.julialang.org/u/stevengj)\
**Post date:** [August 29, 2025, 12:23pm UTC](https://discourse.julialang.org/t/loading-a-library-which-depends-on-another-library/131922/3 "2025-08-29T12:23:09Z")

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> [@cjdoris](#):
>
> I’m no expert but I think maybe if you do `dlopen("libLean_shared")` first, with the right flags, then the system remembers where this library is when it needs to load it again.

In particular, from the [`dlopen` documentation](https://docs.julialang.org/en/v1/stdlib/Libdl/#Base.Libc.Libdl.dlopen):

> For instance `RTLD_LAZY|RTLD_DEEPBIND|RTLD_GLOBAL` allows the library’s symbols to be available for usage in other shared libraries, addressing situations where there are dependencies between shared libraries.