Failed to execute goal org.bytedeco:javacpp:1.5.9:build (javacpp-cppbuild-compile) on project libnd4j: Failed to execute JavaCPP Builder: Cannot run program "sh" (in directory "D:\IDEA2018\deeplearning4j-master\libnd4j"): CreateProcess error=2, 系统找不到指定的文件。

It seems like you are facing an error while executing the JavaCPP Builder in your Maven project. The error message states that the program "sh" cannot be found in the specified directory, which is causing the build process to fail.

This error is usually caused by a missing or misconfigured shell environment on your system. The "sh" program is a Unix shell that is commonly used on Linux and Mac systems, but it may not be available on Windows systems.

To resolve this issue, you can try one of the following solutions:

1. If you are using a Windows system, you can try installing a Unix-like shell such as Git Bash or Cygwin, which should provide the "sh" program and other Unix utilities that are needed for the build process.

2. If you already have a Unix-like shell installed, you can check your system PATH environment variable to make sure that the directory containing the "sh" program is included. You can do this by running the following command in a terminal:

echo $PATH

This should display a list of directories separated by colons. Make sure that the directory containing the "sh" program is included in this list.

3. If you are still encountering issues, you can try updating your Maven configuration to use a different build tool or version of the JavaCPP library. You can also try reaching out to the JavaCPP community or the developers of the project you are working on for further assistance.