The **`WORKDIR` command** is used to define the *working directory* of a Docker container at any given time. The command is specified in the Dockerfile.

Any `RUN`, `CMD`, `ADD`, `COPY`, or `ENTRYPOINT` command will be executed in the specified working directory. 




If the `WORKDIR` command is not written in the Dockerfile, it will automatically be created by the Docker compiler. Hence, it can be said that the command performs `mkdir` and `cd` implicitly.

Here's a sample Dockerfile in which the working directory is set to `/project`:


FROM ubuntu:16.04

WORKDIR /project

RUN npm install 

If the `project` directory does not exist, it will be created. The `RUN` command will be executed inside `project`.

# Reusing `WORKDIR`
`WORKDIR` can be reused to set a new working directory at any stage of the Dockerfile. The path of the new working directory must be given relative to the current working directory.

FROM ubuntu:16.04

WORKDIR /project

RUN npm install 

WORKDIR ../project2

RUN touch file1.cpp

While directories can be manually made and changed, it is strongly recommended that you use `WORKDIR` to specify the current directory in which you would like to work as​ it makes troubleshooting easier.

What is the WORKDIR command in Docker?

Reusing WORKDIR

Reusing `WORKDIR`