# Creating GitHub CLI extensions

Learn how to share new GitHub CLI commands with other users by creating custom extensions for GitHub CLI.

## About GitHub CLI extensions

GitHub CLI extensions are custom GitHub CLI commands that anyone can create and use. For more information about how to use GitHub CLI extensions, see [Using GitHub CLI extensions](/en/github-cli/github-cli/using-github-cli-extensions).

You need a repository for each extension that you create. The repository name must start with `gh-`. The rest of the repository name is the name of the extension. The repository must have an executable file at its root with the same name as the repository or a set of precompiled binary executables attached to a release.

> \[!NOTE]
> When relying on an executable script, we recommend using a bash script because bash is a widely available interpreter. You may use non-bash scripts, but the user must have the necessary interpreter installed in order to use the extension. If you would prefer to not rely on users having interpreters installed, consider a precompiled extension.

## Creating an interpreted extension with `gh extension create`

> \[!NOTE]
> Running `gh extension create` with no arguments will start an interactive wizard.

You can use the `gh extension create` command to create a project for your extension, including a bash script that contains some starter code.

1. Set up a new extension by using the `gh extension create` subcommand. Replace `EXTENSION-NAME` with the name of your extension.

   ```shell
   gh extension create EXTENSION-NAME
   ```

2. Follow the printed instructions to finalize and optionally publish your extension.

## Creating a precompiled extension in Go with `gh extension create`

You can use the `--precompiled=go` argument to create a Go-based project for your extension, including Go scaffolding, workflow scaffolding, and starter code.

1. Set up a new extension by using the `gh extension create` subcommand. Replace `EXTENSION-NAME` with the name of your extension and specify `--precompiled=go`.

   ```shell
   gh extension create --precompiled=go EXTENSION-NAME
   ```

2. Follow the printed instructions to finalize and optionally publish your extension.

## Creating a non-Go precompiled extension with `gh extension create`

You can use the `--precompiled=other` argument to create a project for your non-Go precompiled extension, including workflow scaffolding.

1. Set up a new extension by using the `gh extension create` subcommand. Replace `EXTENSION-NAME` with the name of your extension and specify `--precompiled=other`.

   ```shell
   gh extension create --precompiled=other EXTENSION-NAME
   ```

2. Add some initial code for your extension in your compiled language of choice.

3. Fill in `script/build.sh` with code to build your extension to ensure that your extension can be built automatically.

4. Follow the printed instructions to finalize and optionally publish your extension.

## Creating an interpreted extension manually

1. Create a local directory called `gh-EXTENSION-NAME` for your extension. Replace `EXTENSION-NAME` with the name of your extension. For example, `gh-whoami`.

2. In the directory that you created, add an executable file with the same name as the directory.

   > \[!NOTE]
   > Make sure that your file is executable. On Unix, you can execute `chmod +x file_name` in the command line to make `file_name` executable. On Windows, you can run `git init -b main`, `git add file_name`, then `git update-index --chmod=+x file_name`.

3. Write your script in the executable file. For example:

   ```bash
   #!/usr/bin/env bash
   set -e
   exec gh api user --jq '"You are @\(.login) (\(.name))."'
   ```

4. From your directory, install the extension as a local extension.

   ```shell
   gh extension install .
   ```

5. Verify that your extension works. Replace `EXTENSION-NAME` with the name of your extension. For example, `whoami`.

   ```shell
   gh EXTENSION-NAME
   ```

6. From your directory, create a repository to publish your extension. Replace `EXTENSION-NAME` with the name of your extension.

   ```shell
   git init -b main
   git add . && git commit -m "initial commit"
   gh repo create gh-EXTENSION-NAME --source=. --public --push
   ```

7. Optionally, to help other users discover your extension, add the repository topic `gh-extension`. This will make the extension appear on the [`gh-extension` topic page](https://github.com/topics/gh-extension). For more information about how to add a repository topic, see [Classifying your repository with topics](/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/classifying-your-repository-with-topics).

## Tips for writing interpreted GitHub CLI extensions

### Handling arguments and flags

All command line arguments following a `gh my-extension-name` command will be passed to the extension script. In a bash script, you can reference arguments with `$1`, `$2`, etc. You can use arguments to take user input or to modify the behavior of the script.

For example, this script handles multiple flags. When the script is called with the `-h` or `--help` flag, the script prints help text instead of continuing execution. When the script is called with the `--name` flag, the script sets the next value after the flag to `name_arg`. When the script is called with the `--verbose` flag, the script prints a different greeting.

```bash
#!/usr/bin/env bash
set -e

verbose=""
name_arg=""
while [ $# -gt 0 ]; do
  case "$1" in
  --verbose)
    verbose=1
    ;;
  --name)
    name_arg="$2"
    shift
    ;;
  -h|--help)
    echo "Add help text here."
    exit 0
    ;;
  esac
  shift
done

if [ -z "$name_arg" ]
then
  echo "You haven't told us your name."
elif [ -z "$verbose" ]
then
  echo "Hi $name_arg"
else
  echo "Hello and welcome, $name_arg"
fi
```

### Calling core commands in non-interactive mode

Some GitHub CLI core commands will prompt the user for input. When scripting with those commands, a prompt is often undesirable. To avoid prompting, supply the necessary information explicitly via arguments.

For example, to create an issue programmatically, specify the title and body:

```shell
gh issue create --title "My Title" --body "Issue description"
```

### Fetching data programmatically

Many core commands support the `--json` flag for fetching data programmatically. For example, to return a JSON object listing the number, title, and mergeability status of pull requests:

```shell
gh pr list --json number,title,mergeStateStatus
```

If there is not a core command to fetch specific data from GitHub, you can use the [`gh api`](https://cli.github.com/manual/gh_api) command to access the GitHub API. For example, to fetch information about the current user:

```shell
gh api user
```

All commands that output JSON data also have options to filter that data into something more immediately usable by scripts. For example, to get the current user's name:

```shell
gh api user --jq '.name'
```

For more information, see [`gh help formatting`](https://cli.github.com/manual/gh_help_formatting).

## Creating a precompiled extension manually

1. Create a local directory called `gh-EXTENSION-NAME` for your extension. Replace `EXTENSION-NAME` with the name of your extension. For example, `gh-whoami`.

2. In the directory you created, add some source code. For example:

   ```golang
   package main
   import (
     "github.com/cli/go-gh"
     "fmt"
   )

   func main() {
     args := []string{"api", "user", "--jq", `"You are @\(.login) (\(.name))"` }
     stdOut, _, err := gh.Exec(args...)
     if err != nil {
       fmt.Println(err)
       return
     }
     fmt.Println(stdOut.String())
   }
   ```

3. From your directory, install the extension as a local extension.

   ```shell
   gh extension install .
   ```

4. Build your code. For example, with Go, replacing `YOUR-USERNAME` with your GitHub username:

   ```shell
   go mod init github.com/YOUR-USERNAME/gh-whoami
   go mod tidy
   go build
   ```

5. Verify that your extension works. Replace `EXTENSION-NAME` with the name of your extension. For example, `whoami`.

   ```shell
   gh EXTENSION-NAME
   ```

6. From your directory, create a repository to publish your extension. Replace `EXTENSION-NAME` with the name of your extension.

   > \[!NOTE]
   > Be careful not to commit the binary produced by your compilation step to version control.

   ```shell
    git init -b main
   echo "gh-EXTENSION-NAME" >> .gitignore
   git add main.go go.* .gitignore && git commit -m 'Initial commit'
   gh repo create "gh-EXTENSION-NAME"
   ```

7. Create a release to share your precompiled extension with others. Compile for each platform you want to support, attaching each binary to a release as an asset. Binary executables attached to releases must follow a naming convention and have a suffix of OS-ARCHITECTURE\[EXTENSION].

   For example, an extension named `whoami` compiled for Windows 64bit would have the name `gh-whoami-windows-amd64.exe` while the same extension compiled for Linux 32bit would have the name `gh-whoami-linux-386`. To see an exhaustive list of OS and architecture combinations recognized by `gh`, see [this source code](https://github.com/cli/cli/blob/14f704fd0da58cc01413ee4ba16f13f27e33d15e/pkg/cmd/extension/manager.go#L696).

   > \[!NOTE]
   > For your extension to run properly on Windows, its asset file must have a `.exe` extension. No extension is needed for other operating systems.

   Releases can be created from the command line. For example:

   ```shell
   git tag v1.0.0
   git push origin v1.0.0
   GOOS=windows GOARCH=amd64 go build -o gh-EXTENSION-NAME-windows-amd64.exe
   GOOS=linux GOARCH=amd64 go build -o gh-EXTENSION-NAME-linux-amd64
   GOOS=darwin GOARCH=amd64 go build -o gh-EXTENSION-NAME-darwin-amd64
   gh release create v1.0.0 ./*amd64*

   ```

8. Optionally, to help other users discover your extension, add the repository topic `gh-extension`. This will make the extension appear on the [`gh-extension` topic page](https://github.com/topics/gh-extension). For more information about how to add a repository topic, see [Classifying your repository with topics](/en/github/administering-a-repository/managing-repository-settings/classifying-your-repository-with-topics).

## Tips for writing precompiled GitHub CLI extensions

### Automating releases

Consider adding the [gh-extension-precompile](https://github.com/cli/gh-extension-precompile) action to a workflow in your project. This action will automatically produce cross-compiled Go binaries for your extension and supplies build scaffolding for non-Go precompiled extensions.

### Using GitHub CLI features from Go-based extensions

Consider using [go-gh](https://github.com/cli/go-gh), a Go library that exposes pieces of `gh` functionality for use in extensions.

## Next steps

To see more examples of GitHub CLI extensions, look at [repositories with the `gh-extension` topic](https://github.com/topics/gh-extension).