如何在CMake中正确链接libssh库？编译报错求助

问题场景 #

编译使用libSSH的C项目时遭遇链接错误，编译器提示多个libSSH核心函数未定义，具体错误信息如下：

intero@:~/Documents/projects/c/fastDeploy/build$ make
Consolidate compiler generated dependencies of target deployExe

[ 50%] Linking C executable deployExe/usr/bin/ld: CMakeFiles/deployExe.dir/main.c.o: in function `set_ssh_options':
main.c:(.text+0x2cc): undefined reference to `ssh_options_set'

/usr/bin/ld: main.c:(.text+0x2e5): undefined reference to `ssh_options_set'

/usr/bin/ld: main.c:(.text+0x2fe): undefined reference to `ssh_options_set'

/usr/bin/ld: CMakeFiles/deployExe.dir/main.c.o: in function `main':

main.c:(.text+0x359): undefined reference to `ssh_new'

/usr/bin/ld: main.c:(.text+0x3ab): undefined reference to `ssh_free'

collect2: error: ld returned 1 exit status

make[2]: *** [CMakeFiles/deployExe.dir/build.make:97: deployExe] Error 1

make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/deployExe.dir/all] Error 2

make: *** [Makefile:91: all] Error 2

当前使用的CMakeLists.txt：

cmake_minimum_required(VERSION 3.2)
project(fastDeploy)
add_executable(deployExe main.c)

find_package(LibSSH REQUIRED)
target_link_libraries(deployExe PRIVATE ${LIBSSH_LIBRARIES})

系统中已找到的libSSH路径：

intero@intero-MS-7971:~/Documents/projects/c/fastDeploy$ sudo find /  -name 'libssh'
/usr/include/libssh
/usr/lib/x86_64-linux-gnu/cmake/libssh
find: ‘/tmp/.mount_nvimN16HgQ’: Permission denied

解决步骤 #

1. 修正CMake链接目标 #

新版LibSSH的CMake配置推荐使用导入目标LibSSH::libssh而非旧版的LIBSSH_LIBRARIES变量，修改CMakeLists.txt如下：

cmake_minimum_required(VERSION 3.2)
project(fastDeploy)
add_executable(deployExe main.c)

find_package(LibSSH REQUIRED)
target_link_libraries(deployExe PRIVATE LibSSH::libssh)

导入目标会自动处理头文件路径和依赖库链接，避免变量名不匹配导致的链接失败。

2. 清理CMake缓存并重新构建 #

如果之前的CMake缓存残留了错误配置，执行以下命令重置构建环境：

cd build
rm -rf *
cmake ..
make

3. 确认libSSH开发包完整安装 #

若系统仅安装了libSSH运行时库，缺少头文件或链接库会导致此错误。在Debian/Ubuntu系系统中安装完整开发包：

sudo apt install libssh-dev

4. 修复代码中的参数错误 #

你的set_ssh_options函数存在常量使用错误，第三行的端口设置误用了SSH_OPTIONS_HOST，应改为SSH_OPTIONS_PORT：

void set_ssh_options(ssh_session session, ConnectionInfo *credentials) {
  ssh_options_set(session, SSH_OPTIONS_HOST, &credentials->host);
  ssh_options_set(session, SSH_OPTIONS_LOG_VERBOSITY, &credentials->verbosity);
  ssh_options_set(session, SSH_OPTIONS_PORT, &credentials->port); // 修正此处常量
}

此错误虽不影响编译，但会导致运行时无法正确设置SSH端口，建议一并修复。

内容的提问来源于stack exchange，提问作者intero