The **`ADD` command** is used to copy files/directories into a Docker image. It can copy data in *three* ways:

- Copy files from the local storage to a destination in the Docker image.

- Copy a *tarball* from the local storage and extract it automatically inside a destination in the Docker image.

- Copy files from a URL to a destination inside the Docker image.



# Syntax
The `ADD` command requires a `source` and a `destination`.

```dockerfile
ADD source destination
``` 

- If `source` is a file, it is simply copied to the `destination` directory.

- If `source` is a directory, its *contents* are copied to the `destination`, but the directory itself is not copied.

- `source` can be either a tarball or a URL (as well).

- `source` needs to be within the directory where the `docker build` command was run.

- Multiple sources can be used in one `ADD` command.

# Code

Let's suppose that, in the [Dockerfile](https://www.educative.io/answers/how-do-you-write-a-dockerfile) directory, we have a folder called `codes` which contains multiple C++ files. 

Here's how we can add all the files of the folder to a `test` directory in our Docker image:






FROM ubuntu:latest
RUN mkdir root
RUN cd root
WORKDIR /root
RUN mkdir test
ADD codes /root/test

To add specific files from the `codes` folder, we can specify their names in the `ADD` command:

```dockerfile
ADD codes/file1.cpp codes/file2.cpp root/test/
```

> When adding multiple source files or directories, there must be a `/` at the end of the destination directory.

The same syntax is followed for tarballs and URLs.

What is the Docker ADD command?

The ADD command is used to copy files/directories into a Docker image. It can copy data in three ways:   Copy files from the local storage to a destination in the Docker image.   Copy a tarball from the local storage and extract it automatically inside a destination in the Docker image.   Copy files from a URL to a destination inside the Docker image.   