[9] CMake - 如何高效使用"cmake --help" ?

本帖子适用于继续深入学习者，进阶掌握需要自己的检索和查找能力，本文给出一些方式方法。

安装好cmake之后，其实就自带了最为丰富也是最为权威的说明文档，也就是”cmake –help”，以下简要介绍。

command

cmake –help-commands
这个命令给出cmake内置的命令的详细帮助
cmake –help-command-list
打印出所有command列表

下面给出如何查找一个命令解析的大概过程（Linux）：
（Win下可以重定向到文本中，使用编辑器进行查找）
cmake –help-command-list | grep find
可以在list中查找带find的命令
cmake –help-command find_library
获得find_library的详细解释

module

用于查找常用的模块，譬如boost，bzip2, python等。

通过简单的include命令包含预定义的模块，就可以得到一些模块执行后定义好的变量，非常方便。

譬如常用的boost库，可以通过如下方式：
# Find boost 1.40
INCLUDE(FindBoost)
find_package(Boost 1.40.0 COMPONENTS thread unit_test_framework)
if(NOT Boost_FOUND)
message(STATUS “BOOST not found, test will not succeed!”)
endif()
一般开头部分的解释都相当有用，可满足80%需求：

cmake –help-module FindBoost |head -40

FindBoost---------Find Boost include dirs and librariesUse this module by invoking find_package with the form:: find_package(Boost   [version] [EXACT]      # Minimum or EXACT version e.g. 1.36.0   [REQUIRED]             # Fail with error if Boost is not found   [COMPONENTS <libs>...] # Boost libraries by their canonical name   )                      # e.g. "date_time" for "libboost_date_time"This module finds headers and requested component libraries OR a CMakepackage configuration file provided by a "Boost CMake" build.  For thelatter case skip to the "Boost CMake" section below.  For the formercase results are reported in variables:: Boost_FOUND            - True if headers and requested libraries were found Boost_INCLUDE_DIRS     - Boost include directories Boost_LIBRARY_DIRS     - Link directories for Boost libraries Boost_LIBRARIES        - Boost component libraries to be linked Boost_<C>_FOUND        - True if component <C> was found (<C> is upper-case) Boost_<C>_LIBRARY      - Libraries to link for component <C> (may include                          target_link_libraries debug/optimized keywords) Boost_VERSION          - BOOST_VERSION value from boost/version.hpp Boost_LIB_VERSION      - Version string appended to library filenames Boost_MAJOR_VERSION    - Boost major version number (X in X.y.z) Boost_MINOR_VERSION    - Boost minor version number (Y in x.Y.z) Boost_SUBMINOR_VERSION - Boost subminor version number (Z in x.y.Z) Boost_LIB_DIAGNOSTIC_DEFINITIONS (Windows)                        - Pass to add_definitions() to have diagnostic                          information about Boost's automatic linking                          displayed during compilationThis module reads hints about search locations from variables:: BOOST_ROOT             - Preferred installation prefix  (or BOOSTROOT) BOOST_INCLUDEDIR       - Preferred include directory e.g. <prefix>/include

property

Property一般很少需要直接改动，除非你想修改一些默认的行为，譬如修改生成的动态库文件的soname等。

譬如需要在同一个目录下既生成动态库，也生成静态库，那么默认的情况下，cmake根据你提供的target名字自动生成类似的libtarget.so, libtarget.a，但是同一个project只能同时有一个，因为target必须唯一。

这时候，就可以通过修改taget对应的文件名，从而达到既生成动态库也产生静态库的目的。

cmake --help-property-list | grep NAME:<CONFIG>_OUTPUT_NAMEARCHIVE_OUTPUT_NAMEARCHIVE_OUTPUT_NAME_<CONFIG>COMPILE_PDB_NAMECOMPILE_PDB_NAME_<CONFIG>EXPORT_NAMEGENERATOR_FILE_NAMEIMPORTED_NO_SONAMEIMPORTED_NO_SONAME_<CONFIG>IMPORTED_SONAMEIMPORTED_SONAME_<CONFIG>INSTALL_NAME_DIRLIBRARY_OUTPUT_NAMELIBRARY_OUTPUT_NAME_<CONFIG>NAMENO_SONAMEOUTPUT_NAMEOUTPUT_NAME_<CONFIG>PDB_NAMEPDB_NAME_<CONFIG>RUNTIME_OUTPUT_NAMERUNTIME_OUTPUT_NAME_<CONFIG>VS_GLOBAL_ROOTNAMESPACEVS_SCC_PROJECTNAME

cmake --help-property OUTPUT_NAME:OUTPUT_NAME-----------Output name for target files.This sets the base name for output files created for an executable orlibrary target.  If not set, the logical target name is used bydefault.

variable

可以查找cmake自己定义了哪些变量你可以直接使用，譬如OSName，是否是Windows，Unix等。

cmake --help-variable-list | grep CMAKE | grep HOST:CMAKE_HOST_APPLECMAKE_HOST_SYSTEMCMAKE_HOST_SYSTEM_NAMECMAKE_HOST_SYSTEM_PROCESSORCMAKE_HOST_SYSTEM_VERSIONCMAKE_HOST_UNIXCMAKE_HOST_WIN32

cmake --help-variable CMAKE_HOST_SYSTEM:CMAKE_HOST_SYSTEM-----------------Composit Name of OS CMake is being run on.This variable is the composite of ``CMAKE_HOST_SYSTEM_NAME`` and``CMAKE_HOST_SYSTEM_VERSION``, e.g.``${CMAKE_HOST_SYSTEM_NAME}-${CMAKE_HOST_SYSTEM_VERSION}``.  If``CMAKE_HOST_SYSTEM_VERSION`` is not set, then this variable isthe same as ``CMAKE_HOST_SYSTEM_NAME``.

进阶文档

https://cmake.org/ 介绍与下载
https://cmake.org/install/ 安装方法
https://cmake.org/mailing-lists/ 邮件组
https://cmake.org/cmake/help/cmake2.6docs.html 参考文档
https://cmake.org/Wiki/CMake/Language_Syntax 语法释义
https://cmake.org/Wiki/CMake:Articles
https://cmake.org/Wiki/CMake_FAQ 问题集锦
https://cmake.org/cmake/help/v2.8.8/cmake.html#section_Commands CMake 2.8 的命令可以在此查询
https://techbase.kde.org/Development/CMake
https://techbase.kde.org/Policies/CMake_Coding_Style 代码风格