… not set (j92)

This PR was squashed before being merged into the 4.4 branch (closes #31546).

Discussion
----------

[Dotenv] Use default value when referenced variable is not set

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | yes <!-- please update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #...   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#11956 <!-- required for new features -->

In bash you have the option to define a default variable like this:
```bash
FOO=${VARIABLE:-default}
```

When VARIABLE is not set
```bash
FOO=${VARIABLE:-default} #FOO=default
```

When VARIABLE is set:
```bash
VARIABLE=test
FOO=${VARIABLE:-default} #FOO=test
```

If others find this also a good idea, I will write documentation and add the Doc PR. But first I would like some feedback to check if anyone agrees with this feature.

Commits
-------

790dbad149 [Dotenv] Use default value when referenced variable is not set

… not set (j92)

This PR was squashed before being merged into the 4.4 branch (closes #31546).

Discussion
----------

[Dotenv] Use default value when referenced variable is not set

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | yes <!-- please update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #...   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#11956 <!-- required for new features -->

In bash you have the option to define a default variable like this:
```bash
FOO=${VARIABLE:-default}
```

When VARIABLE is not set
```bash
FOO=${VARIABLE:-default} #FOO=default
```

When VARIABLE is set:
```bash
VARIABLE=test
FOO=${VARIABLE:-default} #FOO=test
```

If others find this also a good idea, I will write documentation and add the Doc PR. But first I would like some feedback to check if anyone agrees with this feature.

Commits
-------

790dbad [Dotenv] Use default value when referenced variable is not set

This PR was merged into the 4.4 branch.

Discussion
----------

Added small section about default values

<!--

If your pull request fixes a BUG, use the oldest maintained branch that contains
the bug (see https://symfony.com/roadmap for the list of maintained branches).

If your pull request documents a NEW FEATURE, use the same Symfony branch where
the feature was introduced (and `master` for features of unreleased versions).

-->

Added a short description and a code sample of how to use default values when referenced variables are not set. The feature PR is symfony/symfony#31546.

Commits
-------

1848e00 Added small section about default values

* 4.4:
  Add missing versionadded directive. refs #11956
  Added small section about default values