CMake Error: Could Not Find pthread Library While Installing ns-allinone-3.37 and opengym

Question

I installed ns-allinone-3.37 and the opengym library in the /home/chae/ns-allinone-3.37/ns-3.37 directory.

The next step was to run the command cmake . in that directory.

(ns3-gym-env) chae@chae-B660M-HD3P:~/ns-allinone-3.37/ns-3.37$ cmake .

However, I encountered an error indicating that the program couldn't find the pthread library.

I am not exactly sure which target library uses pthread or how to fix the CMakeLists.txt accordingly. Additionally, there might be a large number of targets involved.

How can I resolve this issue? What should be my next steps?

Thank you for your help!

The two picture below is the relevant portion of the error message at /home/chae/ns-allinone-3.37/ns-3.37/cmake-cache/CMakeFiles/CMakeError.log.

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