pi@raspberrypi:/mnt/mounted_usb/cppJson $ make
[ 50%] Linking CXX executable main
/usr/bin/ld: CMakeFiles/main.dir/main.cpp.o: in function `main':
main.cpp:(.text.startup+0x8): undefined reference to `curl_easy_init'
/usr/bin/ld: main.cpp:(.text.startup+0x1c): undefined reference to `curl_easy_setopt'
/usr/bin/ld: main.cpp:(.text.startup+0x2c): undefined reference to `curl_easy_setopt'
/usr/bin/ld: main.cpp:(.text.startup+0x3c): undefined reference to `curl_easy_setopt'
/usr/bin/ld: main.cpp:(.text.startup+0x44): undefined reference to `curl_easy_perform'
/usr/bin/ld: main.cpp:(.text.startup+0x54): undefined reference to `curl_easy_cleanup'
/usr/bin/ld: main.cpp:(.text.startup+0x244): undefined reference to `curl_easy_strerror'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/main.dir/build.make:84: main] Error 1
make[1]: *** [CMakeFiles/Makefile2:73: CMakeFiles/main.dir/all] Error 2
make: *** [Makefile:84: all] Error 2