{% endhighlight %}

[Codefresh variables]({{site.baseurl}}/docs/codefresh-yaml/variables/) are**not** interpolated inside the main hook segments.

The following will NOT work:

{% highlight yaml %}

{% raw %}

hooks:

on_finish:

exec:

image: alpine:latest

commands:

- echo $CF_BUILD_ID

{% endraw %}

{% endhighlight %}

However, you can use interpolations inside the`environment` block. The following WILL work:

{% highlight yaml %}

{% raw %}

hooks:

on_finish:

exec:

image: alpine:latest

environment:

- WCF_BUILD_ID=${{CF_BUILD_ID}}

commands:

- echo $WCF_BUILD_ID

{% endraw %}

{% endhighlight %}

In other words, interpolation in the 'environment' block works just fine. And you can use the environment variables set there in the commands block.

There is one MAJOR caveat. This only works for variables present when the build starts. It does NOT work for any variables created or modified in the pipeline_while it runs_. So basically the`CF_*` variables and anything sent in by the pipeline or trigger settings will work as expected, but custom variables created with`cf_export` will not work.

With the current implementation of hooks, the following limitations are present:

* The[debugger]({{site.baseurl}}/docs/configure-ci-cd-pipeline/debugging-pipelines/) cannot inspect commands inside hook segments

* Hooks are not supported for[parallel steps]({{site.baseurl}}/docs/codefresh-yaml/advanced-workflows/)

* Exporting variables with[cf_export]({{site.baseurl}}/docs/codefresh-yaml/variables/#using-cf_export-command) does not work inside hooks

* Storage integrations don't resolve in hooks (for example,[test reports]({{site.baseurl}}/docs/testing/test-reports/#producing-allure-test-reports-from-codefresh-pipelines))

- Custom plugins can be used in hooks -[documentation]({{site.baseurl}}/docs/codefresh-yaml/hooks/#limitations-of-pipelinestep-hooks)

- Variables can now be used in hooks -[documentation]({{site.baseurl}}/docs/codefresh-yaml/hooks/#limitations-of-pipelinestep-hooks)

- New`CF_STEP_NAME` variable -[documentation]({{site.baseurl}}/docs/codefresh-yaml/variables/#system-provided-variables)