# Link error

**URL:** <https://www.ruby-forum.com/t/link-error/233974>\
**Category:** GNU Radio\
**Created:** [January 27, 2015, 3:08pm UTC](https://www.ruby-forum.com/t/link-error/233974 "2015-01-27T15:08:44Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [January 27, 2015, 3:08pm UTC](https://www.ruby-forum.com/t/link-error/233974/1 "2015-01-27T15:08:44Z")

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Hi all:  
Thank you in advance.  
I have use the tool “gr\_modtool” to create a cpp document.But  
an error exists:  
ImportError: /usr/local/lib/libgnuradio-mimo.so: undefined  
symbol: \_ZTIN2gr4mimo21csi\_int\_cfo\_vcvc\_implE  
I have search the maillist,and find “sudo ldconfig” to solve it.But when  
I use the “sudo ldconfig”,the error also exists.  
Can someone help me?Thanks.  
Best regards,  
zs

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**Author:** ![zszszs](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/5fc32e/32.png) [@zszszs](https://www.ruby-forum.com/u/zszszs)\
**Post date:** [January 27, 2015, 4:14pm UTC](https://www.ruby-forum.com/t/link-error/233974/2 "2015-01-27T16:14:22Z")

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I’m fighting a similar kind of error with QT right now. I’ll pass along  
some debug that I was asked to do. First open a terminal and execute the  
following:

ldd /usr/local/lib/libgnuradio-mimo.so | grep libgnu

Then search for the file it reports back like this:

sudo find / -name ‘filename.so\*’

If you find multiple versions of the file, for example,  
filename.so.5.1.1  
and filename.so.5.2.0, then it probably means one version is interfering  
with the other and casuing you trouble. Get rid of the problem version.

Hope that helps,  
Rich

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**Author:** ![zszszs](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/5fc32e/32.png) [@zszszs](https://www.ruby-forum.com/u/zszszs)\
**Post date:** [January 28, 2015, 10:12am UTC](https://www.ruby-forum.com/t/link-error/233974/3 "2015-01-28T10:12:35Z")

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On Tue, Jan 27, 2015 at 8:35 AM, zs [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> zs

zs,

Have you gone through our tutorials?

[http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided\_Tutorials](http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorials)

That walks through the process of creating your own module and blocks.  
It  
might point out something that you did incorrectly when building your  
own.  
There is also the tutorial on building out-of-tree modules that might  
also  
be of use:

[http://gnuradio.org/redmine/projects/gnuradio/wiki/OutOfTreeModules](http://gnuradio.org/redmine/projects/gnuradio/wiki/OutOfTreeModules)

Tom