This is a small utility program to apply a dockerignore on a path. .dockerignore files are documented https://docs.docker.com/engine/reference/builder/. As they use Go's filepath.Match rules it is not possible to apply simple bash filter to the dockerignore file.
The use case is where the repository is ADD'ed via a tar file to the docker image temporary directory rather than being processed normally. This program can then be used to post-process that unpacked tar prior to it being manipulated inside the image.
Usage
applydockerignore
The .dockerignore file must exist within the target path.