Could NOT find OpenSSL, try to set the path to OpenSSL root folder 解决方法

在进行编译mosquitto时遇到以下问题：

CMake Error at /usr/local/share/cmake-3.5/Modules/FindPackageHandleStandardArgs.cmake:148 (message):
  Could NOT find OpenSSL, try to set the path to OpenSSL root folder in the
  system variable OPENSSL_ROOT_DIR (missing: OPENSSL_LIBRARIES
  OPENSSL_INCLUDE_DIR)
Call Stack (most recent call first):
  /usr/local/share/cmake-3.5/Modules/FindPackageHandleStandardArgs.cmake:388 (_FPHSA_FAILURE_MESSAGE)
  /usr/local/share/cmake-3.5/Modules/FindOpenSSL.cmake:370 (find_package_handle_standard_args)
  CMakeLists.txt:61 (find_package)

在确认已经安装OpenSSL的情况下，查看OpenSSL安装目录
/usr/local/lib/libssl.so
/usr/local/lib/libssl.so.1.0.0
/usr/local/lib/libssl.a
/usr/local/ssl/lib/libssl.so
/usr/local/ssl/lib/libssl.so.1.0.0
/usr/local/ssl/lib/libssl.a

解决办法：

cmake ../ -DOPENSSL_ROOT_DIR=/usr/local/ssl -DOPENSSL_LIBRARIES=/usr/local/ssl/lib

之后继续安装即可

参考文章：
https://stackoverflow.com/questions/16248775/cmake-not-able-to-find-openssl-library

CMake not able to find OpenSSL library

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I am trying to install a software, which uses cmake to install itself, when i give at commandlin cmake ..
 it gives me following error in this file, CMakeLists.txt -------- line ---> find_package(OpenSSL REQUIRED) :--
 cmake ..
-- Could NOT find Git (missing:  GIT_EXECUTABLE) 
ZLib include dirs: /usr/include
ZLib libraries: /usr/lib/arm-linux-gnueabihf/libz.so
Compiling with SSL support
CMake Error at /usr/local/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:97 (message):
  Could NOT find OpenSSL, try to set the path to OpenSSL root folder in the
  system variable OPENSSL_ROOT_DIR (missing: OPENSSL_LIBRARIES
  OPENSSL_INCLUDE_DIR)
Call Stack (most recent call first):
  /usr/local/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:291 (_FPHSA_FAILURE_MESSAGE)
  /usr/local/share/cmake-2.8/Modules/FindOpenSSL.cmake:313 (find_package_handle_standard_args)
  CMakeLists.txt:436 (find_package)


Here is the part of file CMakeLists.txt, where error is comming :------
#
# OpenSSL
#
if (WITH_SSL)
    message("Compiling with SSL support")

    if (USE_CYASSL)
        # Use CyaSSL as OpenSSL replacement.
        # TODO: Add a find_package command for this also.
        message("CyaSSL include dir: ${CYASSL_INCLUDE_DIRS}")
        message("CyaSSL libraries: ${CYASSL_LIB}")

        # Additional to the root directory we need to include
        # the cyassl/ subdirectory which contains the OpenSSL
        # compatability layer headers.
        foreach(inc ${CYASSL_INCLUDE_DIRS})
            include_directories(${inc} ${inc}/cyassl)
        endforeach()

        list(APPEND LIB_LIST ${CYASSL_LIB})
    else()
        # TODO: Add support for STATIC also.
        find_package(OpenSSL REQUIRED)

        message("OpenSSL include dir: ${OPENSSL_INCLUDE_DIR}")
        message("OpenSSL libraries: ${OPENSSL_LIBRARIES}")

        include_directories(${OPENSSL_INCLUDE_DIR})
        list(APPEND LIB_LIST ${OPENSSL_LIBRARIES})
    endif()
endif(WITH_SSL)

 Now i have installed Openssl, here :---- 
ssl header is here   -- > /usr/local/ssl/include/openssl/
ssl library is here  -- > /usr/local/ssl/lib/libssl.a
                          /usr/local/ssl/lib/libcrypto.a
openssl is here      -- > /usr/local/ssl/bin


I have set my .profile as :----
export LD_LIBRARY_PATH=/usr/local/ssl/include/openssl:/usr/lib:/usr/local/lib:/usr/lib/pkgconfig:/usr/local/include/wx-2.8/wx:$LD_LIBRARY_PATH
export PKG_CONFIG_PATH=/usr/lib/pkgconfig
export OPENSSL_ROOT_DIR=/usr/local/ssl
export OPENSSL_LIBRARIES=/usr/local/ssl/lib/

PATH = /usr/local/ssl/bin:$PATH

How to resolve this error ?


It is a common misunderstanding: CMake does not need environment variables to know where the library and include dir are but CMake variables.

Since CMake can not find your OpenSSL lib and include directory, you will have to manually tell him where they are with its command line when you call it. Use the option -D to set constants in CMake from the command line. You will need to set the constants OPENSSL_ROOT_DIR and OPENSSL_LIBRARIES since they are the one triggering the error.


cmake -DOPENSSL_ROOT_DIR=/usr/local/ssl -DOPENSSL_LIBRARIES=/usr/local/ssl/lib