Phony targets in Makefiles

written by Eric J. Ma on 2021-03-04 | tags: automation computation reproducibility

Makefiles can be used to create a lightweight CLI entry point for your project. By writing a Makefile, you can automate repetitive shell commands, such as building a Dockerfile (which might require you to remember certain incantations):

.PHONY: container

container:
    docker build -t mycontainer -f Dockerfile .

Doing so allows us to build a Docker container using the command make container when at the command line.

Now, you'll probably notice the .PHONY line at the top. What's that all about?

By convention, the command container would have referred to a file target on disk. (This is how Makefiles were originally designed.) However, if we want the command to be independent of any files on disk, we declare it to be a phony target that doesn't actually exist on disk.

Cite this blog post:

@article{
    ericmjl-2021-phony-makefiles,
    author = {Eric J. Ma},
    title = {Phony targets in Makefiles},
    year = {2021},
    month = {03},
    day = {04},
    howpublished = {\url{https://ericmjl.github.io}},
    journal = {Eric J. Ma's Blog},
    url = {https://ericmjl.github.io/blog/2021/3/4/phony-targets-in-makefiles},
}

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