# Undefined symbol

**URL:** <https://discourse.julialang.org/t/undefined-symbol/41165>\
**Category:** General Usage\
**Created:** [June 10, 2020, 10:17pm UTC](https://discourse.julialang.org/t/undefined-symbol/41165 "2020-06-10T22:17:52Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Zhang\_Wei](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/zhang_wei/32/14115_2.png) [@Zhang\_Wei](https://discourse.julialang.org/u/Zhang_Wei)\
**Post date:** [June 10, 2020, 10:17pm UTC](https://discourse.julialang.org/t/undefined-symbol/41165/1 "2020-06-10T22:17:52Z")

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Hi,  
I creat my dynamic libray test.so on Linux, I can use it in my Intel Fortran code. But when I use it in Julia in ccall, I get error: undefined symbol. I have export LD\_LIBRARY=$PWD. Any idea about this error? Thanks!

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**Author:** ![pixel27](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pixel27/32/8902_2.png) [@pixel27](https://discourse.julialang.org/u/pixel27)\
**Post date:** [June 10, 2020, 10:48pm UTC](https://discourse.julialang.org/t/undefined-symbol/41165/2 "2020-06-10T22:48:25Z")

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[https://stackoverflow.com/questions/34732/how-do-i-list-the-symbols-in-a-so-file](https://stackoverflow.com/questions/34732/how-do-i-list-the-symbols-in-a-so-file)

Check the symbol names actually exported by the library, make sure you are have it spelled right.

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**Author:** ![jlapeyre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jlapeyre/32/4514_2.png) [@jlapeyre](https://discourse.julialang.org/u/jlapeyre)\
**Post date:** [June 11, 2020, 5:14am UTC](https://discourse.julialang.org/t/undefined-symbol/41165/3 "2020-06-11T05:14:32Z")

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Which symbol is undefined? Is it in `test.so` or in a library that `test.so` depends on?

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**Author:** ![Zhang\_Wei](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/zhang_wei/32/14115_2.png) [@Zhang\_Wei](https://discourse.julialang.org/u/Zhang_Wei)\
**Post date:** [June 11, 2020, 6:16am UTC](https://discourse.julialang.org/t/undefined-symbol/41165/4 "2020-06-11T06:16:23Z")

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Hi John, it’s a symbol in a library that `test.so` depends on.

John Lapeyre via JuliaLang \<[julialang@discoursemail.com](mailto:julialang@discoursemail.com)\> 于2020年6月11日周四 上午7:19写道：

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**Author:** ![Zhang\_Wei](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/zhang_wei/32/14115_2.png) [@Zhang\_Wei](https://discourse.julialang.org/u/Zhang_Wei)\
**Post date:** [June 11, 2020, 8:37am UTC](https://discourse.julialang.org/t/undefined-symbol/41165/5 "2020-06-11T08:37:03Z")

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Hi, the problem is when I generated test.so, I forget the flag -L. Thanks for you help!

Zhang Wei \<[zhangweiuio@gmail.com](mailto:zhangweiuio@gmail.com)\> 于2020年6月11日周四 上午8:16写道：

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**Author:** ![jlapeyre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jlapeyre/32/4514_2.png) [@jlapeyre](https://discourse.julialang.org/u/jlapeyre)\
**Post date:** [June 11, 2020, 11:44am UTC](https://discourse.julialang.org/t/undefined-symbol/41165/6 "2020-06-11T11:44:37Z")

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> [@Ccall to libgsl fails](https://discourse.julialang.org/t/ccall-to-libgsl-fails/11957):
>
> Hello, I am trying to use ccall in julia for the first time and I can’t make a simple call to libgsl: ccall((:gsl\_sf\_gamma\_inc\_Q, :libgsl), Cdouble, (Cdouble, Cdouble), 0.2, 0.2) returns: ERROR: LoadError: error compiling anonymous: could not load library "libgsl" /usr/lib/libgsl.so: undefined symbol: cblas\_ctrmv What is the problem here? I have cblas installed… Thanks for help.