Ninja Not Found by Cmake

My solution: symlink "ninja-build" to "ninja".

# ln -s /usr/bin/ninja /usr/bin/ninja-build

This only works on very old versions of CMake, which I will explain below.

I had already dropped my fresh "ninja" binary into /usr/bin and checked it had 0755 permissions. I was stumped until I ran an strace on the generator command.

# strace cmake -GNinja .. | grep -i ninja
access("ninja-build", R_OK)             = -1 ENOENT (No such file or directory)
access("/usr/local/sbin/ninja-build", R_OK) = -1 ENOENT (No such file or directory)
access("/usr/local/bin/ninja-build", R_OK) = -1 ENOENT (No such file or directory)
access("/sbin/ninja-build", R_OK)       = -1 ENOENT (No such file or directory)
access("/bin/ninja-build", R_OK)        = -1 ENOENT (No such file or directory)
access("/usr/sbin/ninja-build", R_OK)   = -1 ENOENT (No such file or directory)
access("/usr/bin/ninja-build", R_OK)    = -1 ENOENT (No such file or directory)
access("/opt/texlive/2016/bin/i386-linux/ninja-build", R_OK) = -1 ENOENT (No such file or directory)
access("/root/bin/ninja-build", R_OK)   = -1 ENOENT (No such file or directory)

It was looking for "ninja-build", not "ninja"!

I use CMake with Ninja extensively at work and at home, on Windows and Linux. So why haven't I seen this bug before?

Well... in this instance I'm using a very old version of CMake, version 2.8.12. It's so old it's almost fossilised. So presumably it's either a CMake bug which was fixed later, or the Ninja project changed the name of the binary at some point.

If ninja really exists in $PATH and it still does not work, you should check the permission of the executable file via ls -l /PATH/TO/NINJA. Make sure others have read and execute permissions (like '-rwxr-xr-x').

See also: 0013910: Ninja generator initialization fails if /usr/bin/ninja is not world-readable

You may still suffer

CMake Error: CMake was unable to find a build program corresponding to "Ninja".  CMAKE_MAKE_PROGRAM is not set.  You probably need to select a different build tool.

even you already have::

• put ninja in your PATH
• ninja executable with proper privilege
• newer version of cmake**

Then it might because -D CMAKE_MAKE_PROGRAM and -G Ninja are specified at the same time but CMAKE_MAKE_PROGRAM with invalid value (such as empty).

For example

Android Studio with gradle plugin version :

classpath 'com.android.tools.build:gradle:7.0.0-alpha03'

and not using SDK Manager provided cmake, by:

• put cmake executable in PATH environment variable
• put ninja executable in PATH environment variable
• specify cmake version equal to the one in PATH, in modules's build.gradle, like:

    externalNativeBuild {
        cmake {
            path "src/main/cpp/CMakeLists.txt"
            version "3.19.1" // this line
        }
    }

Then actually gradle calling cmake like this:

cmake ^
-HD:\dev\android_cv_examples\HelloNDK7\app\src\main\cpp ^
-DCMAKE_SYSTEM_NAME=Android ^
-DCMAKE_EXPORT_COMPILE_COMMANDS=ON ^
-DCMAKE_SYSTEM_VERSION=26 ^
-DANDROID_ABI=arm64-v8a ^
-DCMAKE_ANDROID_ARCH_ABI=arm64-v8a ^
-DANDROID_NDK=D:\soft\Android\ndk-r21b ^
-DCMAKE_ANDROID_NDK=D:\soft\Android\ndk-r21b ^
-DCMAKE_TOOLCHAIN_FILE=D:\soft\Android\ndk-r21b\build\cmake\android.toolchain.cmake ^
-DCMAKE_MAKE_PROGRAM= ^
-DCMAKE_C_FLAGS= ^
-DCMAKE_CXX_FLAGS=-std=c++11 ^
-DCMAKE_LIBRARY_OUTPUT_DIRECTORY=D:\dev\android_cv_examples\HelloNDK7\app\build\intermediates\cmake\debug\obj\arm64-v8a ^
-DCMAKE_RUNTIME_OUTPUT_DIRECTORY=D:\dev\android_cv_examples\HelloNDK7\app\build\intermediates\cmake\debug\obj\arm64-v8a ^
-DCMAKE_BUILD_TYPE=Debug ^
-BD:\dev\android_cv_examples\HelloNDK7\app\.cxx\cmake\debug\arm64-v8a ^
-GNinja ^
-DANDROID_PLATFORM=android-24

Note: If removing previous cmake build cache, and modify that calling script by deleting -DCMAKE_MAKE_PROGRAM then problem will be solved.

My issue was fixed by upgrading CMake to the latest version as specified in this answer:

This was apparently an issue in CMake that is now fixed in the latest version. More information here:

In Debian/Ubuntu systems, go ahead and install it

apt install ninja-build

Then rerun CMake.

I am using Mac Monterey. I put ninja into /Applications and /Users/USER/Applications and made sure $PATH was pointing to these directories, but no luck.

I only made CMake discover Ninja by installing it via homebrew:

brew install ninja