CMake: Print out all accessible variables in a script

Using the get_cmake_property function, the following loop will print out all CMake variables defined and their values:

get_cmake_property(_variableNames VARIABLES)
list (SORT _variableNames)
foreach (_variableName ${_variableNames})
    message(STATUS "${_variableName}=${${_variableName}}")
endforeach()

This can also be embedded in a convenience function which can optionally use a regular expression to print only a subset of variables with matching names

function(dump_cmake_variables)
    get_cmake_property(_variableNames VARIABLES)
    list (SORT _variableNames)
    foreach (_variableName ${_variableNames})
        if (ARGV0)
            unset(MATCHED)
            string(REGEX MATCH ${ARGV0} MATCHED ${_variableName})
            if (NOT MATCHED)
                continue()
            endif()
        endif()
        message(STATUS "${_variableName}=${${_variableName}}")
    endforeach()
endfunction()

To print environment variables, use CMake's command mode:

execute_process(COMMAND "${CMAKE_COMMAND}" "-E" "environment")

Another way is to simply use:

cmake -LAH

From the manpage:

-L[A][H] List non-advanced cached variables. List cache variables will run CMake and list all the variables from the CMake cache that are not marked as INTERNAL or ADVANCED. This will effectively display current CMake settings [...]. If A is specified, then it will display also advanced variables. If H is specified, it will also display help for each variable.

ccmake is a good interactive option to interactively inspect cached variables (option( or set( CACHE:

sudo apt-get install cmake-curses-gui
mkdir build
cd build
cmake ..
ccmake ..

https://i.stack.imgur.com/ohmjl.png

Another way to view all cmake's internal variables, is by executing cmake with the --trace-expand option.

This will give you a trace of all .cmake files executed and variables set on each line.

based on @sakra

function(dump_cmake_variables)
    get_cmake_property(_variableNames VARIABLES)
    list (SORT _variableNames)
    foreach (_variableName ${_variableNames})
        if (ARGV0)
            unset(MATCHED)

            #case sensitive match
            # string(REGEX MATCH ${ARGV0} MATCHED ${_variableName})
            #
            #case insenstitive match
            string( TOLOWER "${ARGV0}" ARGV0_lower )
            string( TOLOWER "${_variableName}" _variableName_lower )
            string(REGEX MATCH ${ARGV0_lower} MATCHED ${_variableName_lower})

            if (NOT MATCHED)
                continue()
            endif()
        endif()
        message(STATUS "${_variableName}=${${_variableName}}")
    endforeach()
endfunction()

dump_cmake_variables("^Boost")

variable names are case sensitive

btw if you are interested in boost, it is Boost_INCLUDE_DIRS not BOOST_INCLUDE_DIRS, and it is Boost_LIBRARIES not BOOST_LIBRARIES, and by mistake I had BOOST_LIBRARIES instead of Boost_LIBRARIES, https://cmake.org/cmake/help/v3.0/module/FindBoost.html , better example for boost:

set(Boost_USE_STATIC_LIBS ON)
find_package(Boost REQUIRED COMPONENTS RANDOM)
include_directories(${Boost_INCLUDE_DIRS})

target_link_libraries(myfile PRIVATE
 ${Boost_LIBRARIES}
)

None of the current answers allowed me to see the variables in my project subdirectory. Here's a solution:

function(print_directory_variables dir)
    # Dump variables:
    get_property(_variableNames DIRECTORY ${dir} PROPERTY VARIABLES)
    list (SORT _variableNames)
    foreach (_variableName ${_variableNames})
        get_directory_property(_variableValue DIRECTORY ${dir} DEFINITION ${_variableName})
        message(STATUS "DIR ${dir}: ${_variableName}=${_variableValue}")
    endforeach()
endfunction(print_directory_variables)

# for example
print_directory_variables(.)
print_directory_variables(ui/qt)

You can use message :

message([STATUS] "SUB_SOURCES : ${SUB_SOURCES}")