添加libsystemd依赖失败：CMake无法找到libsystemd包求助

尝试添加libsystemd依赖以使用头文件#include <systemd/sd-daemon.h>，但构建时出错，报错日志及对应的CMakeLists.txt代码如下：

构建报错日志 #

-- Found Boost: /usr/lib/x86_64-linux-gnu/cmake/Boost-1.71.0/BoostConfig.cmake (found version "1.71.0") found components: system thread filesystem 
-- Checking for module 'libsystemd'
--   No package 'libsystemd' found
-- Configuring incomplete, errors occurred!
See also "/home/src/build-tiles-Desktop_Qt_5_15_2_GCC_64bit-Debug/CMakeFiles/CMakeOutput.log".
See also "/home/src/build-tiles-Desktop_Qt_5_15_2_GCC_64bit-Debug/CMakeFiles/CMakeError.log".
SIMPLE_WEB_SERVER include dir =/home/src/polaris-tiles/style-server/Simple-Web-Server
SIMPLE_WEB_SERVER include dir =/home/src/polaris-tiles/tile-server/Simple-Web-Server
CMake Error at /home/Qt/Tools/CMake/share/cmake-3.21/Modules/FindPkgConfig.cmake:554 (message):
  A required package was not found
Call Stack (most recent call first):
  /home/Qt/Tools/CMake/share/cmake-3.21/Modules/FindPkgConfig.cmake:776 (_pkg_check_modules_internal)
  Simple-Web-Server/CMakeLists.txt:22 (pkg_check_modules)

关联的CMakeLists.txt代码 #

cmake_minimum_required(VERSION 3.0)

project(Simple-Web-Server)

include(GNUInstallDirs)


option(USE_STANDALONE_ASIO "set ON to use standalone Asio instead of Boost.Asio" OFF)
if(CMAKE_SOURCE_DIR STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
   option(BUILD_TESTING "set ON to build library tests" ON)
else()
   option(BUILD_TESTING "set ON to build library tests" OFF)
endif()
option(BUILD_FUZZING "set ON to build library fuzzers" OFF)
option(USE_OPENSSL "set OFF to build without OpenSSL" ON)

add_library(simple-web-server INTERFACE)

target_include_directories(simple-web-server INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})

find_package(PkgConfig REQUIRED)
pkg_check_modules(SYSTEMD REQUIRED IMPORTED_TARGET libsystemd)

find_package(Threads REQUIRED)

target_link_libraries(simple-web-server INTERFACE PkgConfig::SYSTEMD)
target_link_libraries(simple-web-server INTERFACE ${CMAKE_THREAD_LIBS_INIT})

# TODO 2020 when Debian Jessie LTS ends:
# Remove Boost system, thread, regex components; use Boost::<component> aliases; remove Boost target_include_directories
if(USE_STANDALONE_ASIO)
   message("USING STANDALONE")
   target_compile_definitions(simple-web-server INTERFACE ASIO_STANDALONE)
   find_path(ASIO_PATH asio.hpp)
   if(NOT ASIO_PATH)
       message(FATAL_ERROR "Standalone Asio not found")
   else()
       target_include_directories(simple-web-server INTERFACE ${ASIO_PATH})
   endif()
else()
   message("NOT USING STANDALONE")
   find_package(Boost 1.53.0 COMPONENTS system thread REQUIRED)
   target_link_libraries(simple-web-server INTERFACE ${Boost_LIBRARIES})
   target_include_directories(simple-web-server INTERFACE ${Boost_INCLUDE_DIR})
   if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9)
       target_compile_definitions(simple-web-server INTERFACE USE_BOOST_REGEX)
       find_package(Boost 1.53.0 COMPONENTS regex REQUIRED)
       target_link_libraries(simple-web-server INTERFACE ${Boost_LIBRARIES})
       target_include_directories(simple-web-server INTERFACE ${Boost_INCLUDE_DIR})
   endif()
endif()
if(WIN32)
   target_link_libraries(simple-web-server INTERFACE ws2_32 wsock32)
endif()

if(APPLE)
   set(OPENSSL_ROOT_DIR "/usr/local/opt/openssl")
endif()
if(USE_OPENSSL)
   find_package(OpenSSL)
endif()
if(OPENSSL_FOUND)
   target_compile_definitions(simple-web-server INTERFACE HAVE_OPENSSL)
   target_link_libraries(simple-web-server INTERFACE ${OPENSSL_LIBRARIES})
   target_include_directories(simple-web-server INTERFACE ${OPENSSL_INCLUDE_DIR})
endif()

# If Simple-Web-Server is not a sub-project:
if(CMAKE_SOURCE_DIR STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
   message("NOT A SUB-PROJECT")
   if(NOT MSVC)
       add_compile_options(-std=c++11 -Wall -Wextra)
       if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
           add_compile_options(-Wthread-safety)
       endif()
   else()
       add_compile_options(/W1)
   endif()

   find_package(Boost 1.53.0 COMPONENTS system thread filesystem)
   if(Boost_FOUND)
       add_executable(http_examples http_examples.cpp)
       target_link_libraries(http_examples simple-web-server)
       target_link_libraries(http_examples ${Boost_LIBRARIES})
       target_include_directories(http_examples PRIVATE ${Boost_INCLUDE_DIR})
       if(OPENSSL_FOUND)
           add_executable(https_examples https_examples.cpp)
           target_link_libraries(https_examples simple-web-server)
           target_link_libraries(https_examples ${Boost_LIBRARIES})
           target_include_directories(https_examples PRIVATE ${Boost_INCLUDE_DIR})
       endif()
    endif()

   install(FILES asio_compatibility.hpp server_http.hpp client_http.hpp server_https.hpp client_https.hpp crypto.hpp utility.hpp status_code.hpp mutex.hpp DESTINATION include/simple-web-server)
endif()

if(BUILD_TESTING OR BUILD_FUZZING)
   if(BUILD_TESTING)
       enable_testing()
   endif()
   add_subdirectory(tests)
endif()

1. 安装libsystemd开发依赖 #

报错核心是系统找不到libsystemd的pkgconfig配置文件，这是因为缺少对应的开发包，根据你的发行版执行以下命令安装：

• Debian/Ubuntu：

sudo apt-get install libsystemd-dev

• RHEL/CentOS：

sudo yum install systemd-devel

• Fedora：

sudo dnf install systemd-devel

2. 修正CMake配置（可选） #

如果安装后仍报错，可能是pkgconfig包名差异，部分系统中libsystemd的pkgconfig文件名为systemd而非libsystemd，修改CMakeLists.txt中的对应行：
将：

pkg_check_modules(SYSTEMD REQUIRED IMPORTED_TARGET libsystemd)

替换为：

pkg_check_modules(SYSTEMD REQUIRED IMPORTED_TARGET systemd)

如果libsystemd安装在非标准路径，需手动指定pkgconfig路径：

set(ENV{PKG_CONFIG_PATH} "/自定义路径/lib/pkgconfig:$ENV{PKG_CONFIG_PATH}")
pkg_check_modules(SYSTEMD REQUIRED IMPORTED_TARGET libsystemd)

3. 验证头文件路径 #

确保/usr/include/systemd/sd-daemon.h存在，若不存在，检查开发包是否安装正确，或手动添加头文件路径到CMake配置：

target_include_directories(simple-web-server INTERFACE /usr/include/systemd)

内容的提问来源于stack exchange，提问作者island slangz