diff --git a/.docker/main/composer.json b/.docker/main/composer.json
index eba4dca..615684c 100644
--- a/.docker/main/composer.json
+++ b/.docker/main/composer.json
@@ -40,7 +40,8 @@
             "composer/installers": true,
             "drupal/core-composer-scaffold": true,
             "drupal/core-project-message": true,
-            "drupal/core-vendor-hardening": true
+            "drupal/core-vendor-hardening": true,
+            "dealerdirect/phpcodesniffer-composer-installer": true
         }
     },
     "extra": {
diff --git a/README.md b/README.md
index bf499b4..dc4fcc4 100644
--- a/README.md
+++ b/README.md
@@ -256,6 +256,32 @@ do
 done;
 ```
 
+### site:keys
+
+Get a list of all keys in `$sites`. Usually, these are site URIs.
+
+#### Example: Usage
+
+```shell
+$ drall site:keys
+tmnt.com
+donatello.com
+leonardo.com
+michelangelo.com
+raphael.com
+```
+
+The output can then be iterated with scripts.
+
+#### Example: Iterating
+
+```shell
+for site in $(drall site:keys)
+do
+  echo "Current site: $site";
+done;
+```
+
 ### site:aliases
 
 Get a list of site aliases.
diff --git a/composer.json b/composer.json
index 5ea01ea..cf989ef 100644
--- a/composer.json
+++ b/composer.json
@@ -53,6 +53,9 @@
         },
         "sort-packages": true
     },
+    "extra": {
+        "phpcodesniffer-search-depth": 5
+    },
     "scripts": {
         "lint": "composer exec phpcs",
         "test": "XDEBUG_MODE=coverage composer exec phpunit"
diff --git a/src/Command/BaseCommand.php b/src/Command/BaseCommand.php
index b67ebb1..2c99ff3 100644
--- a/src/Command/BaseCommand.php
+++ b/src/Command/BaseCommand.php
@@ -5,9 +5,9 @@
 use Drall\Trait\SiteDetectorAwareTrait;
 use Psr\Log\LoggerAwareTrait;
 use Symfony\Component\Console\Command\Command;
-use Symfony\Component\Console\Logger\ConsoleLogger;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Logger\ConsoleLogger;
 use Symfony\Component\Console\Output\OutputInterface;
 
 abstract class BaseCommand extends Command {
diff --git a/src/Command/ExecCommand.php b/src/Command/ExecCommand.php
index b140365..b442751 100644
--- a/src/Command/ExecCommand.php
+++ b/src/Command/ExecCommand.php
@@ -50,9 +50,10 @@ protected function configure() {
     $this->setAliases(['ex']);
     $this->setDescription('Execute a command on multiple Drupal sites.');
     $this->addUsage('drush core:status');
-    $this->addUsage('--drall-group=bluish drush core:status');
-    $this->addUsage('--drall-workers=4 drush cache:rebuild');
     $this->addUsage('./vendor/bin/drush core:status');
+    $this->addUsage('--drall-group=GROUP drush core:status');
+    $this->addUsage('--drall-filter=FILTER drush core:status');
+    $this->addUsage('--drall-workers=4 drush cache:rebuild');
     $this->addUsage('ls web/sites/@@dir/settings.php');
     $this->addUsage('echo "Working on @@site" && drush @@site.local core:status');
 
diff --git a/src/Command/SiteAliasesCommand.php b/src/Command/SiteAliasesCommand.php
index bfd09c0..701c820 100644
--- a/src/Command/SiteAliasesCommand.php
+++ b/src/Command/SiteAliasesCommand.php
@@ -15,9 +15,10 @@ protected function configure() {
 
     $this->setName('site:aliases');
     $this->setAliases(['sa']);
-    $this->setDescription('Get a list of site aliases.');
+    $this->setDescription('List all Drush site aliases.');
     $this->addUsage('site:aliases');
     $this->addUsage('--drall-group=GROUP site:aliases');
+    $this->addUsage('--drall-filter=FILTER  site:aliases');
   }
 
   protected function execute(InputInterface $input, OutputInterface $output) {
diff --git a/src/Command/SiteDirectoriesCommand.php b/src/Command/SiteDirectoriesCommand.php
index 0e0b6a5..f993974 100644
--- a/src/Command/SiteDirectoriesCommand.php
+++ b/src/Command/SiteDirectoriesCommand.php
@@ -6,7 +6,7 @@
 use Symfony\Component\Console\Output\OutputInterface;
 
 /**
- * A command to get a list of site directories in the Drupal installation.
+ * A command to get a list of values in the $sites array.
  */
 class SiteDirectoriesCommand extends BaseCommand {
 
@@ -15,7 +15,7 @@ protected function configure() {
 
     $this->setName('site:directories');
     $this->setAliases(['sd']);
-    $this->setDescription('Get a list of site directories.');
+    $this->setDescription('List the values of the $sites array.');
     $this->addUsage('site:directories');
     $this->addUsage('--drall-group=GROUP site:directories');
   }
diff --git a/src/Command/SiteKeysCommand.php b/src/Command/SiteKeysCommand.php
new file mode 100644
index 0000000..550438c
--- /dev/null
+++ b/src/Command/SiteKeysCommand.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace Drall\Command;
+
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * A command to get a list of keys in the $sites array.
+ */
+class SiteKeysCommand extends BaseCommand {
+
+  protected function configure() {
+    parent::configure();
+
+    $this->setName('site:keys');
+    $this->setAliases(['sk']);
+    $this->setDescription('List the keys of the $sites array.');
+    $this->addUsage('site:keys');
+    $this->addUsage('--drall-group=GROUP site:keys');
+    $this->addUsage('--drall-filter=FILTER site:keys');
+  }
+
+  protected function execute(InputInterface $input, OutputInterface $output) {
+    $this->preExecute($input, $output);
+
+    $keys = $this->siteDetector()
+      ->getSiteKeys(
+        $this->getDrallGroup($input),
+        $this->getDrallFilter($input),
+      );
+
+    if (count($keys) === 0) {
+      $this->logger->warning('No Drupal sites found.');
+      return 0;
+    }
+
+    foreach ($keys as $key) {
+      $output->writeln($key);
+    }
+
+    return 0;
+  }
+
+}
diff --git a/src/Drall.php b/src/Drall.php
index 597c642..97f127d 100644
--- a/src/Drall.php
+++ b/src/Drall.php
@@ -4,13 +4,14 @@
 
 use Consolidation\SiteAlias\SiteAliasManager;
 use Drall\Command\ExecCommand;
-use Drall\Command\SiteDirectoriesCommand;
 use Drall\Command\SiteAliasesCommand;
+use Drall\Command\SiteDirectoriesCommand;
+use Drall\Command\SiteKeysCommand;
 use Drall\Model\EnvironmentId;
 use Drall\Service\SiteDetector;
 use Drall\Trait\SiteDetectorAwareTrait;
-use Drush\SiteAlias\SiteAliasFileLoader;
 use DrupalFinder\DrupalFinder;
+use Drush\SiteAlias\SiteAliasFileLoader;
 use Symfony\Component\Console\Application;
 use Symfony\Component\Console\Exception\CommandNotFoundException;
 use Symfony\Component\Console\Input\ArgvInput;
@@ -52,6 +53,10 @@ public function __construct(
     $cmd->setSiteDetector($siteDetector);
     $this->add($cmd);
 
+    $cmd = new SiteKeysCommand();
+    $cmd->setSiteDetector($siteDetector);
+    $this->add($cmd);
+
     $cmd = new SiteAliasesCommand();
     $cmd->setSiteDetector($siteDetector);
     $this->add($cmd);
diff --git a/src/Service/SiteDetector.php b/src/Service/SiteDetector.php
index 55ce102..e0c1cc3 100644
--- a/src/Service/SiteDetector.php
+++ b/src/Service/SiteDetector.php
@@ -6,9 +6,9 @@
 use Consolidation\Filter\LogicalOpFactory;
 use Consolidation\SiteAlias\SiteAliasManagerAwareTrait;
 use Consolidation\SiteAlias\SiteAliasManagerInterface;
+use Drall\Model\SitesFile;
 use Drall\Trait\DrupalFinderAwareTrait;
 use DrupalFinder\DrupalFinder;
-use Drall\Model\SitesFile;
 
 class SiteDetector {
 
diff --git a/test/Integration/Command/SiteAliasesCommandTest.php b/test/Integration/Command/SiteAliasesCommandTest.php
index 3c69555..37cf644 100644
--- a/test/Integration/Command/SiteAliasesCommandTest.php
+++ b/test/Integration/Command/SiteAliasesCommandTest.php
@@ -34,7 +34,7 @@ public function testExecute(): void {
   }
 
   /**
-   * Run site:aliases with --filter.
+   * Run site:aliases with --drall-filter.
    */
   public function testExecuteWithFilter(): void {
     $output = shell_exec('drall site:aliases --drall-filter="leo||ralph"');
diff --git a/test/Integration/Command/SiteDirectoriesCommandTest.php b/test/Integration/Command/SiteDirectoriesCommandTest.php
index 0e0f9af..7e20f00 100644
--- a/test/Integration/Command/SiteDirectoriesCommandTest.php
+++ b/test/Integration/Command/SiteDirectoriesCommandTest.php
@@ -34,7 +34,7 @@ public function testExecute(): void {
   }
 
   /**
-   * Run site:directories with --filter.
+   * Run site:directories with --drall-filter.
    */
   public function testExecuteWithFilter(): void {
     $output = shell_exec('drall site:directories --drall-filter="leo||ralph"');
diff --git a/test/Integration/Command/SiteKeysCommandTest.php b/test/Integration/Command/SiteKeysCommandTest.php
new file mode 100644
index 0000000..1a2434a
--- /dev/null
+++ b/test/Integration/Command/SiteKeysCommandTest.php
@@ -0,0 +1,128 @@
+<?php
+
+namespace Drall\Test\Integration\Commands;
+
+use Drall\IntegrationTestCase;
+
+/**
+ * @covers \Drall\Command\SiteDirectoriesCommand
+ */
+class SiteKeysCommandTest extends IntegrationTestCase {
+
+  /**
+   * Run site:keys with no Drupal installation.
+   */
+  public function testWithNoDrupal(): void {
+    chdir('/tmp');
+    $output = shell_exec('drall site:keys');
+    $this->assertOutputEquals("[warning] No Drupal sites found." . PHP_EOL, $output);
+  }
+
+  /**
+   * Run site:keys with a Drupal installation.
+   */
+  public function testExecute(): void {
+    $output = shell_exec('drall site:keys');
+    $this->assertOutputEquals(<<<EOF
+tmnt.com
+cowabunga.com
+tmnt.drall.local
+donatello.com
+8080.donatello.com
+donnie.drall.local
+leonardo.com
+leo.drall.local
+michelangelo.com
+mikey.drall.local
+raphael.com
+ralph.drall.local
+
+EOF, $output);
+  }
+
+  /**
+   * Run site:keys with --drall-filter.
+   */
+  public function testExecuteWithFilter(): void {
+    $output = shell_exec('drall site:keys --drall-filter="value~=@.local\$@"');
+    $this->assertOutputEquals(<<<EOF
+tmnt.drall.local
+donnie.drall.local
+leo.drall.local
+mikey.drall.local
+ralph.drall.local
+
+EOF, $output);
+  }
+
+  /**
+   * Run site:keys with --drall-group.
+   */
+  public function testWithGroup(): void {
+    $output = shell_exec('drall site:keys --drall-group=bluish');
+    $this->assertOutputEquals(<<<EOF
+donatello.com
+8080.donatello.com
+donnie.drall.local
+leonardo.com
+leo.drall.local
+
+EOF, $output);
+  }
+
+  /**
+   * Run site:keys with DRALL_GROUP env var.
+   */
+  public function testWithGroupEnvVar(): void {
+    $output = shell_exec('DRALL_GROUP=bluish drall site:keys');
+    $this->assertOutputEquals(<<<EOF
+donatello.com
+8080.donatello.com
+donnie.drall.local
+leonardo.com
+leo.drall.local
+
+EOF, $output);
+  }
+
+  public function testWithComposerRoot() {
+    chdir('/');
+    $output = shell_exec('drall --root=' . $this->drupalDir() . ' site:keys');
+    $this->assertEquals(<<<EOF
+tmnt.com
+cowabunga.com
+tmnt.drall.local
+donatello.com
+8080.donatello.com
+donnie.drall.local
+leonardo.com
+leo.drall.local
+michelangelo.com
+mikey.drall.local
+raphael.com
+ralph.drall.local
+
+EOF, $output);
+  }
+
+  public function testWithDrupalRoot() {
+    chdir('/');
+    $output = shell_exec('drall --root=' . $this->drupalDir() . '/web site:keys');
+    $this->assertEquals(<<<EOF
+tmnt.com
+cowabunga.com
+tmnt.drall.local
+donatello.com
+8080.donatello.com
+donnie.drall.local
+leonardo.com
+leo.drall.local
+michelangelo.com
+mikey.drall.local
+raphael.com
+ralph.drall.local
+
+EOF, $output);
+  }
+
+}
diff --git a/test/Unit/Command/ExecCommandTest.php b/test/Unit/Command/ExecCommandTest.php
index 9b5eaed..ec1694a 100644
--- a/test/Unit/Command/ExecCommandTest.php
+++ b/test/Unit/Command/ExecCommandTest.php
@@ -1,13 +1,13 @@
 <?php
 
 use Consolidation\SiteAlias\SiteAliasManager;
-use Symfony\Component\Console\Input\ArrayInput;
-use Symfony\Component\Console\Output\OutputInterface;
-use Symfony\Component\Console\Tester\CommandTester;
-use DrupalFinder\DrupalFinder;
 use Drall\Drall;
 use Drall\Service\SiteDetector;
 use Drall\TestCase;
+use DrupalFinder\DrupalFinder;
+use Symfony\Component\Console\Input\ArrayInput;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Tester\CommandTester;
 
 /**
  * @covers \Drall\Command\ExecCommand
diff --git a/test/Unit/Command/SiteAliasesCommandTest.php b/test/Unit/Command/SiteAliasesCommandTest.php
index 0f25de5..1d1bc09 100644
--- a/test/Unit/Command/SiteAliasesCommandTest.php
+++ b/test/Unit/Command/SiteAliasesCommandTest.php
@@ -1,12 +1,12 @@
 <?php
 
 use Consolidation\SiteAlias\SiteAliasManager;
-use Symfony\Component\Console\Output\BufferedOutput;
-use Symfony\Component\Console\Tester\CommandTester;
-use DrupalFinder\DrupalFinder;
 use Drall\Drall;
 use Drall\Service\SiteDetector;
 use Drall\TestCase;
+use DrupalFinder\DrupalFinder;
+use Symfony\Component\Console\Output\BufferedOutput;
+use Symfony\Component\Console\Tester\CommandTester;
 
 /**
  * @covers \Drall\Command\BaseCommand
diff --git a/test/Unit/Command/SiteDirectoriesCommandTest.php b/test/Unit/Command/SiteDirectoriesCommandTest.php
index bcd805b..b7ab68f 100644
--- a/test/Unit/Command/SiteDirectoriesCommandTest.php
+++ b/test/Unit/Command/SiteDirectoriesCommandTest.php
@@ -1,11 +1,11 @@
 <?php
 
 use Consolidation\SiteAlias\SiteAliasManager;
-use Symfony\Component\Console\Tester\CommandTester;
-use DrupalFinder\DrupalFinder;
 use Drall\Drall;
 use Drall\Service\SiteDetector;
 use Drall\TestCase;
+use DrupalFinder\DrupalFinder;
+use Symfony\Component\Console\Tester\CommandTester;
 
 /**
  * @covers \Drall\Command\BaseCommand
diff --git a/test/Unit/Command/SiteKeysCommandTest.php b/test/Unit/Command/SiteKeysCommandTest.php
new file mode 100644
index 0000000..4e9400d
--- /dev/null
+++ b/test/Unit/Command/SiteKeysCommandTest.php
@@ -0,0 +1,101 @@
+<?php
+
+namespace Unit\Command;
+
+use Consolidation\SiteAlias\SiteAliasManager;
+use Drall\Drall;
+use Drall\Service\SiteDetector;
+use Drall\TestCase;
+use DrupalFinder\DrupalFinder;
+use Symfony\Component\Console\Tester\CommandTester;
+
+/**
+ * @covers \Drall\Command\BaseCommand
+ * @covers \Drall\Command\SiteDirectoriesCommand
+ */
+class SiteKeysCommandTest extends TestCase {
+
+  public function testExecute() {
+    $drupalFinder = new DrupalFinder();
+    $siteAliasManager = new SiteAliasManager();
+
+    $siteDetectorMock = $this->getMockBuilder(SiteDetector::class)
+      ->setConstructorArgs([$drupalFinder, $siteAliasManager])
+      ->onlyMethods(['getSiteKeys'])
+      ->getMock();
+    $siteDetectorMock
+      ->expects($this->once())
+      ->method('getSiteKeys')
+      ->willReturn(['donatello.com', 'leonardo.com']);
+
+    $app = new Drall($siteDetectorMock);
+    $tester = new CommandTester($app->find('site:keys'));
+    $tester->execute([]);
+
+    $tester->assertCommandIsSuccessful();
+
+    $this->assertEquals(
+      <<<EOF
+donatello.com
+leonardo.com
+
+EOF,
+      $tester->getDisplay()
+    );
+  }
+
+  public function testExecuteWithGroup() {
+    $drupalFinder = new DrupalFinder();
+    $siteAliasManager = new SiteAliasManager();
+
+    $siteDetectorMock = $this->getMockBuilder(SiteDetector::class)
+      ->setConstructorArgs([$drupalFinder, $siteAliasManager])
+      ->onlyMethods(['getSiteKeys'])
+      ->getMock();
+    $siteDetectorMock
+      ->expects($this->once())
+      ->method('getSiteKeys')
+      ->with('bluish')
+      ->willReturn(['tmnt.com']);
+
+    $app = new Drall($siteDetectorMock);
+    $tester = new CommandTester($app->find('site:keys'));
+    $tester->execute(['--drall-group' => 'bluish']);
+
+    $tester->assertCommandIsSuccessful();
+
+    $this->assertEquals(
+      <<<EOF
+tmnt.com
+
+EOF,
+      $tester->getDisplay()
+    );
+  }
+
+  public function testExecuteWithNoSiteDirectories() {
+    $drupalFinder = new DrupalFinder();
+    $siteAliasManager = new SiteAliasManager();
+
+    $siteDetectorMock = $this->getMockBuilder(SiteDetector::class)
+      ->setConstructorArgs([$drupalFinder, $siteAliasManager])
+      ->onlyMethods(['getSiteKeys'])
+      ->getMock();
+    $siteDetectorMock
+      ->expects($this->once())
+      ->method('getSiteKeys')
+      ->willReturn([]);
+
+    $app = new Drall($siteDetectorMock);
+    $tester = new CommandTester($app->find('site:keys'));
+    $tester->execute([]);
+
+    $tester->assertCommandIsSuccessful();
+
+    $this->assertEquals(
+      '[warning] No Drupal sites found.' . PHP_EOL,
+      $tester->getDisplay()
+    );
+  }
+
+}