i have no idea what is -j8 -l8 and don't know what to do. Just copied the console.

Base path: /home/minje/catkinws Source space: /home/minje/catkinws/src Build space: /home/minje/catkinws/build Devel space: /home/minje/catkinws/devel Install space: /home/minje/catkin_ws/install

Running command: "make cmakecheckbuildsystem" in "/home/minje/catkinws/build"

Running command: "make -j8 -l8" in "/home/minje/catkin_ws/build"

[ 0%] Built target stdmsgsgeneratemessagespy [ 0%] Built target stdmsgsgeneratemessagescpp [ 0%] Built target stdmsgsgeneratemessageslisp [ 0%] Built target stdmsgsgeneratemessageseus [ 0%] Built target stdmsgsgeneratemessagesnodejs [ 0%] Built target firstpkggeneratemessagescheckdepsAddTwoInts [ 0%] Built target _firstpkggeneratemessagescheckdepsNum [ 15%] Built target firstpkggeneratemessagesnodejs [ 23%] Generating C++ code from firstpkg/Num.msg [ 38%] Built target firstpkggeneratemessageslisp [ 46%] Generating C++ code from firstpkg/AddTwoInts.srv [ 69%] Built target firstpkggeneratemessageseus [100%] Built target firstpkggeneratemessagespy Traceback (most recent call last): File "/opt/ros/melodic/share/gencpp/cmake/../../../lib/gencpp/gencpp.py", line 43, in import genmsg.templatetools Traceback (most recent call last): File "/opt/ros/melodic/lib/python2.7/dist-packages/genmsg/templatetools.py", line 39, in File "/opt/ros/melodic/share/gencpp/cmake/../../../lib/gencpp/gencpp.py", line 43, in import em ModuleNotFoundError: No module named 'em' import genmsg.templatetools File "/opt/ros/melodic/lib/python2.7/dist-packages/genmsg/templatetools.py", line 39, in import em ModuleNotFoundError: No module named 'em' firstpkg/CMakeFiles/firstpkggeneratemessagescpp.dir/build.make:63: recipe for target '/home/minje/catkinws/devel/include/firstpkg/Num.h' failed make[2]: *** [/home/minje/catkinws/devel/include/firstpkg/Num.h] Error 1 make[2]: *** Waiting for unfinished jobs.... firstpkg/CMakeFiles/firstpkggeneratemessagescpp.dir/build.make:70: recipe for target '/home/minje/catkinws/devel/include/firstpkg/AddTwoInts.h' failed make[2]: *** [/home/minje/catkinws/devel/include/firstpkg/AddTwoInts.h] Error 1 CMakeFiles/Makefile2:557: recipe for target 'firstpkg/CMakeFiles/firstpkggeneratemessagescpp.dir/all' failed make[1]: *** [firstpkg/CMakeFiles/firstpkggeneratemessages_cpp.dir/all] Error 2 Makefile:140: recipe for target 'all' failed make: *** [all] Error 2 Invoking "make -j8 -l8" failed