I'm getting an error with the cmake command

[ItsDrike]

My terminal:

root@kali:~/Desktop# git clone https://github.com/n0la/rcon.git
Cloning into 'rcon'...
remote: Enumerating objects: 17, done.
remote: Counting objects: 100% (17/17), done.
remote: Compressing objects: 100% (15/15), done.
remote: Total 190 (delta 2), reused 7 (delta 2), pack-reused 173
Receiving objects: 100% (190/190), 50.11 KiB | 528.00 KiB/s, done.
Resolving deltas: 100% (103/103), done.
root@kali:~/Desktop# cd rcon
root@kali:~/Desktop/rcon# mkdir build
root@kali:~/Desktop/rcon# cd build
root@kali:~/Desktop/rcon/build# cmake .. -DCMAKE_INSTALL_PREFIX=/usr
-- The C compiler identification is GNU 9.2.1
-- The CXX compiler identification is GNU 9.2.1
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Could NOT find PkgConfig (missing: PKG_CONFIG_EXECUTABLE) 
CMake Error at /usr/share/cmake-3.13/Modules/FindPkgConfig.cmake:505 (message):
  pkg-config tool not found
Call Stack (most recent call first):
  /usr/share/cmake-3.13/Modules/FindPkgConfig.cmake:622 (_pkg_check_modules_internal)
  CMakeLists.txt:6 (PKG_CHECK_MODULES)

-- Looking for open_memstream
-- Looking for open_memstream - found
-- Looking for fmemopen
-- Looking for fmemopen - found
-- Looking for arc4random_uniform
-- Looking for arc4random_uniform - not found
-- Looking for pledge
-- Looking for pledge - not found
CMake Error at /usr/share/cmake-3.13/Modules/FindPkgConfig.cmake:505 (message):
  pkg-config tool not found
Call Stack (most recent call first):
  /usr/share/cmake-3.13/Modules/FindPkgConfig.cmake:622 (_pkg_check_modules_internal)
  CMakeLists.txt:43 (PKG_CHECK_MODULES)

CMake Error at /usr/share/cmake-3.13/Modules/FindPkgConfig.cmake:505 (message):
  pkg-config tool not found
Call Stack (most recent call first):
  /usr/share/cmake-3.13/Modules/FindPkgConfig.cmake:622 (_pkg_check_modules_internal)
  tests/CMakeLists.txt:3 (PKG_CHECK_MODULES)

-- Configuring incomplete, errors occurred!
See also "/root/Desktop/rcon/build/CMakeFiles/CMakeOutput.log".
See also "/root/Desktop/rcon/build/CMakeFiles/CMakeError.log".

[lyn1337]

Install pkg-config, you can do this by running apt-get install pkg-config if your dist is using that.

[n0la]

Closing due to inactivity on OP's part. Lyn1337 already answered the question correctly.