diff --git a/.gitattributes b/.gitattributes
index 9cd0768..911dc25 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1,5 +1,6 @@
 * text=auto
 *.sh            eol=lf
+**/sbin/**      eol=lf
 **/run          eol=lf
 */services.d/*  eol=lf
 **/run          eol=lf
diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..35c483d
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+  "files.eol": "\n"
+}
\ No newline at end of file
diff --git a/alpine/docker-compose.yml b/alpine/docker-compose.yml
index e715e71..2d88487 100644
--- a/alpine/docker-compose.yml
+++ b/alpine/docker-compose.yml
@@ -4,6 +4,7 @@ services:
     build: .
     image: homecentr/base:alpine-local
     environment:
+      PUID_ADDITIONAL_GROUPS: "9005:test-group"
       FILE__TEST_VAR: "/var-value.txt"
       UNRELATED: "some-var"
     volumes:
diff --git a/alpine/fs/etc/cont-init.d/01-env.sh b/alpine/fs/etc/cont-init.d/01-env.sh
index fd458c8..810aad7 100644
--- a/alpine/fs/etc/cont-init.d/01-env.sh
+++ b/alpine/fs/etc/cont-init.d/01-env.sh
@@ -1,5 +1,7 @@
 #!/usr/bin/with-contenv ash
 
+source homecentr_set_s6_env_var
+
 MATCHING_FILES=$(find /var/run/s6/container_environment/ -name "FILE__*" | wc -l)
 
 if [ $MATCHING_FILES -le 0 ]; then
@@ -9,14 +11,16 @@ fi
 for FULL_FILENAME in /var/run/s6/container_environment/FILE__*; do
   FILENAME="${FULL_FILENAME#'/var/run/s6/container_environment/'}"
 
-  #if [[ $FILENAME = "FILE__"* ]]; then
-    VAR_VALUE_FILE=$(cat ${FULL_FILENAME})
-    VAR_NAME="${FILENAME#'FILE__'}"
+  VAR_VALUE_FILE=$(cat ${FULL_FILENAME})
+  VAR_NAME="${FILENAME#'FILE__'}"
+
+  if [ -f "$VAR_VALUE_FILE" ]; then
+    VAR_VALUE=$(cat "$VAR_VALUE_FILE")
+
+    homecentr_set_s6_env_var "$VAR_NAME" "$VAR_VALUE"
 
-    if [ -f "$VAR_VALUE_FILE" ]; then
-      cat "$VAR_VALUE_FILE" > "/var/run/s6/container_environment/${VAR_NAME}"
-      echo "[env-vars] Variable $VAR_NAME set from ${VAR_VALUE_FILE}"
-    else
-      echo "[env-vars] Variable $VAR_NAME could not be set from ${VAR_VALUE_FILE}. File not found."
-    fi
+    echo "[env-vars] Variable $VAR_NAME set from ${VAR_VALUE_FILE}"
+  else
+    echo "[env-vars] Variable $VAR_NAME could not be set from ${VAR_VALUE_FILE}. File not found."
+  fi
 done
\ No newline at end of file
diff --git a/alpine/fs/etc/cont-init.d/10-init.sh b/alpine/fs/etc/cont-init.d/10-init.sh
index 3dceb17..e04ca25 100644
--- a/alpine/fs/etc/cont-init.d/10-init.sh
+++ b/alpine/fs/etc/cont-init.d/10-init.sh
@@ -1,4 +1,9 @@
 #!/usr/bin/with-contenv ash
+source homecentr_create_group
+source homecentr_print_banner
+source homecentr_print_context
+source homecentr_set_s6_env_var
+
 EXEC_GROUP="root"
 EXEC_USER="root"
 
@@ -15,16 +20,6 @@ then
   exit 2
 fi
 
-### Verify required packages are available
-if [ "$PGID" != "0" ] || [ "$PUID" != "0" ]
-then
-  if ( ! type "addgroup" > /dev/null; ) || ( ! type "adduser" > /dev/null; )
-  then
-    >&2 echo "Cannot create user/group, please install shadow package!"
-    exit 1
-  fi
-fi
-
 ### Create primary group
 if [ "$PGID" -ne "0" ]
 then
@@ -37,16 +32,8 @@ then
     deluser nonroot
   fi
 
-  # Check if the group exists already
-  cat /etc/group | grep ^nonroot: > /dev/null
+  homecentr_create_group "nonroot" "$PGID"
 
-  if [ $? == 0 ]
-  then
-    # Group already exists, delete it
-    delgroup nonroot
-  fi
-  
-  addgroup -g $PGID nonroot
   EXEC_GROUP="nonroot"
 fi
 
@@ -61,6 +48,13 @@ fi
 ### Create groups
 if [[ ! -z $PUID_ADDITIONAL_GROUPS ]]
 then
+  echo "$PUID_ADDITIONAL_GROUPS" | egrep '^[0-9]+\:[a-zA-Z0-9_-]+(,[0-9]+\:[a-zA-Z0-9_-]+)*$' > /dev/null
+
+  if [ "$?" != "0" ]; then
+    >&2 echo "The value $PUID_ADDITIONAL_GROUPS is invalid. Valid format is <gid1>:<group-name1>,<gid2>:<group-name2>"
+    exit 2
+  fi
+
   # Expecting string in format "gid:name,gid:name"
   GROUPS=$(echo $PUID_ADDITIONAL_GROUPS | tr "," "\n")
 
@@ -69,27 +63,17 @@ then
     GRP_ID=$(echo $GROUP | cut -d ':' -f 1)
     GRP_NAME=$(echo $GROUP | cut -d ':' -f 2)
 
-    # Create group
-    addgroup -g "$GRP_ID" "$GRP_NAME"
+    # Create group (delete if already exists)
+    homecentr_create_group "$GRP_NAME" "$GRP_ID"
 
     # Add user to the group
     addgroup "$EXEC_USER" "$GRP_NAME"
   done
 fi
 
-echo '
-    __  __                                     __
-   / / / /___  ____ ___  ___  ________  ____  / /______
-  / /_/ / __ \/ __ `__ \/ _ \/ ___/ _ \/ __ \/ __/ ___/
- / __  / /_/ / / / / / /  __/ /__/  __/ / / / /_/ /    
-/_/ /_/\____/_/ /_/ /_/\___/\___/\___/_/ /_/\__/_/     
-'
-echo "
--------------------------------------
-User uid:    $(id -u $EXEC_USER)
-User gid:    $(id -g $EXEC_GROUP)
--------------------------------------
-"
-
-# Write the variable so that the runas script can use it
-echo "$EXEC_USER" > /var/run/s6/container_environment/EXEC_USER
\ No newline at end of file
+homecentr_print_banner
+
+# Write the variable so that other scripts can use it
+homecentr_set_s6_env_var "EXEC_USER" "$EXEC_USER"
+
+homecentr_print_context
\ No newline at end of file
diff --git a/alpine/fs/usr/sbin/homecentr_create_group b/alpine/fs/usr/sbin/homecentr_create_group
new file mode 100644
index 0000000..1ba281f
--- /dev/null
+++ b/alpine/fs/usr/sbin/homecentr_create_group
@@ -0,0 +1,17 @@
+#!/usr/bin/with-contenv ash
+
+homecentr_create_group() {
+  # $1 = Group name
+  # $2 = Group ID
+
+  # Check if the group exists already
+  cat /etc/group | grep "^$1:" > /dev/null
+
+  if [ $? == 0 ]
+  then
+    # Group already exists, delete it
+    delgroup "$1"
+  fi
+  
+  addgroup -g "$2" "$1"
+}
\ No newline at end of file
diff --git a/alpine/fs/usr/sbin/homecentr_print_banner b/alpine/fs/usr/sbin/homecentr_print_banner
new file mode 100644
index 0000000..09ec72f
--- /dev/null
+++ b/alpine/fs/usr/sbin/homecentr_print_banner
@@ -0,0 +1,13 @@
+#!/usr/bin/with-contenv ash
+
+homecentr_print_banner() {
+
+echo '
+    __  __                                     __
+   / / / /___  ____ ___  ___  ________  ____  / /______
+  / /_/ / __ \/ __ `__ \/ _ \/ ___/ _ \/ __ \/ __/ ___/
+ / __  / /_/ / / / / / /  __/ /__/  __/ / / / /_/ /    
+/_/ /_/\____/_/ /_/ /_/\___/\___/\___/_/ /_/\__/_/     
+'
+
+}
\ No newline at end of file
diff --git a/alpine/fs/usr/sbin/homecentr_print_context b/alpine/fs/usr/sbin/homecentr_print_context
new file mode 100644
index 0000000..82c516d
--- /dev/null
+++ b/alpine/fs/usr/sbin/homecentr_print_context
@@ -0,0 +1,15 @@
+#!/usr/bin/with-contenv ash
+
+homecentr_print_context() {
+
+# The gids script filters out the primary group so it matches the structure of the env vars passed to the container
+
+echo "
+-------------------------------------
+User uid:               $(id -u $EXEC_USER)
+User gid:               $(id -g $EXEC_USER)
+User additional gids:   $(id -G $EXEC_USER | tr ' ' '\n' | grep -v "^$(id -g $EXEC_USER)$" | tr '\n' ',' | sed 's/,*$//g')
+-------------------------------------
+"
+
+}
\ No newline at end of file
diff --git a/alpine/fs/usr/sbin/homecentr_set_s6_env_var b/alpine/fs/usr/sbin/homecentr_set_s6_env_var
new file mode 100644
index 0000000..d80d875
--- /dev/null
+++ b/alpine/fs/usr/sbin/homecentr_set_s6_env_var
@@ -0,0 +1,8 @@
+#!/usr/bin/with-contenv ash
+
+homecentr_set_s6_env_var() {
+  # $1 = Variable name
+  # $2 = Variable value
+
+  echo "$2" > "/var/run/s6/container_environment/$1"
+}
\ No newline at end of file
diff --git a/tests/src/test/java/BaseRunningWithInvalidSecondaryGroupsAsNonRootShould.java b/tests/src/test/java/BaseRunningWithInvalidSecondaryGroupsAsNonRootShould.java
new file mode 100644
index 0000000..a72144f
--- /dev/null
+++ b/tests/src/test/java/BaseRunningWithInvalidSecondaryGroupsAsNonRootShould.java
@@ -0,0 +1,65 @@
+import helpers.BaseDockerImageTagResolver;
+import helpers.Image;
+import io.homecentr.testcontainers.containers.GenericContainerEx;
+import io.homecentr.testcontainers.containers.wait.strategy.WaitEx;
+import io.homecentr.testcontainers.images.PullPolicyEx;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.testcontainers.containers.ContainerLaunchException;
+import org.testcontainers.containers.GenericContainer;
+import org.testcontainers.containers.output.Slf4jLogConsumer;
+
+import java.nio.file.Paths;
+import java.time.Duration;
+
+import static io.homecentr.testcontainers.WaitLoop.waitFor;
+
+public class BaseRunningWithInvalidSecondaryGroupsAsNonRootShould {
+    private static final Logger logger = LoggerFactory.getLogger(BaseRunningAsRootShould.class);
+
+    private static GenericContainerEx _container;
+
+    @BeforeClass
+    public static void before(){
+        _container = new GenericContainerEx<>(new BaseDockerImageTagResolver())
+                .withEnv("PUID", "7000")
+                .withEnv("PGID", "8000")
+                .withEnv("PUID_ADDITIONAL_GROUPS", "8005=grp1") // valid delimiter is :
+                .withRelativeFileSystemBind(Paths.get(Image.getExamplesDir(), "loop").toString(), "/usr/sbin/loop")
+                .withRelativeFileSystemBind(Paths.get(Image.getExamplesDir(), "run").toString(), "/etc/services.d/env-test/run")
+                .withImagePullPolicy(PullPolicyEx.never())
+                .waitingFor(WaitEx.forS6OverlayStart());
+
+        try
+        {
+            _container.start();
+        }
+        catch (ContainerLaunchException ex) {
+            // Expected
+        }
+    }
+
+    @AfterClass
+    public static void after() {
+        _container.close();
+    }
+
+    @Test
+    public void printErrorMessage() throws Exception {
+        waitFor(Duration.ofSeconds(10), () -> _container.getLogsAnalyzer().matches(".*Valid format is <gid1>:<group-name1>,<gid2>:<group-name2>.*"));
+    }
+
+    @Test
+    public void exitFromInitScript() throws Exception {
+        // This checks the container stopped on the init script and not because of other failure
+        waitFor(Duration.ofSeconds(10), () -> _container.getLogsAnalyzer().matches(".*\\[cont\\-init\\.d\\] 10-init\\.sh: exited.*"));
+    }
+
+    @Test
+    public void exit() throws Exception {
+        waitFor(Duration.ofSeconds(5), () -> !_container.isRunning());
+    }
+}
diff --git a/tests/src/test/java/BaseRunningWithInvalidSecondaryGroupsAsRootShould.java b/tests/src/test/java/BaseRunningWithInvalidSecondaryGroupsAsRootShould.java
new file mode 100644
index 0000000..68d38ad
--- /dev/null
+++ b/tests/src/test/java/BaseRunningWithInvalidSecondaryGroupsAsRootShould.java
@@ -0,0 +1,63 @@
+import helpers.BaseDockerImageTagResolver;
+import helpers.Image;
+import io.homecentr.testcontainers.containers.GenericContainerEx;
+import io.homecentr.testcontainers.containers.wait.strategy.WaitEx;
+import io.homecentr.testcontainers.images.PullPolicyEx;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.testcontainers.containers.ContainerLaunchException;
+
+import java.nio.file.Paths;
+import java.time.Duration;
+
+import static io.homecentr.testcontainers.WaitLoop.waitFor;
+
+public class BaseRunningWithInvalidSecondaryGroupsAsRootShould {
+    private static final Logger logger = LoggerFactory.getLogger(BaseRunningAsRootShould.class);
+
+    private static GenericContainerEx _container;
+
+    @BeforeClass
+    public static void before(){
+        _container = new GenericContainerEx<>(new BaseDockerImageTagResolver())
+                .withEnv("PUID", "0")
+                .withEnv("PGID", "0")
+                .withEnv("PUID_ADDITIONAL_GROUPS", "8005=grp1") // valid delimiter is :
+                .withRelativeFileSystemBind(Paths.get(Image.getExamplesDir(), "loop").toString(), "/usr/sbin/loop")
+                .withRelativeFileSystemBind(Paths.get(Image.getExamplesDir(), "run").toString(), "/etc/services.d/env-test/run")
+                .withImagePullPolicy(PullPolicyEx.never())
+                .waitingFor(WaitEx.forS6OverlayStart());
+
+        try
+        {
+            _container.start();
+        }
+        catch (ContainerLaunchException ex) {
+            // Expected
+        }
+    }
+
+    @AfterClass
+    public static void after() {
+        _container.close();
+    }
+
+    @Test
+    public void printErrorMessage() throws Exception {
+        waitFor(Duration.ofSeconds(10), () -> _container.getLogsAnalyzer().matches(".*Valid format is <gid1>:<group-name1>,<gid2>:<group-name2>.*"));
+    }
+
+    @Test
+    public void exitFromInitScript() throws Exception {
+        // This checks the container stopped on the init script and not because of other failure
+        waitFor(Duration.ofSeconds(10), () -> _container.getLogsAnalyzer().matches(".*\\[cont\\-init\\.d\\] 10-init\\.sh: exited.*"));
+    }
+
+    @Test
+    public void exit() throws Exception {
+        waitFor(Duration.ofSeconds(5), () -> !_container.isRunning());
+    }
+}
diff --git a/tests/src/test/java/BaseRunningWithSecondaryGroupsAsNonRootShould.java b/tests/src/test/java/BaseRunningWithSecondaryGroupsAsNonRootShould.java
index 5d48d2e..a8979d1 100644
--- a/tests/src/test/java/BaseRunningWithSecondaryGroupsAsNonRootShould.java
+++ b/tests/src/test/java/BaseRunningWithSecondaryGroupsAsNonRootShould.java
@@ -57,4 +57,10 @@ public void loadGroupsToPuidUserContext() throws Exception {
         waitFor(Duration.ofSeconds(10), () -> _container.getLogsAnalyzer().matches(".*ID=.*8005\\(grp1\\).*"));
         waitFor(Duration.ofSeconds(10), () -> _container.getLogsAnalyzer().matches(".*ID=.*8006\\(grp2\\).*"));
     }
+
+    @Test
+    public void printGroupsToOutput() throws Exception {
+        // Root is automatically member of other groups
+        waitFor(Duration.ofSeconds(10), () -> _container.getLogsAnalyzer().matches(".*User additional gids:\\W*8005,8006.*"));
+    }
 }
diff --git a/tests/src/test/java/BaseRunningWithSecondaryGroupsAsRootShould.java b/tests/src/test/java/BaseRunningWithSecondaryGroupsAsRootShould.java
index bf31350..d70bad3 100644
--- a/tests/src/test/java/BaseRunningWithSecondaryGroupsAsRootShould.java
+++ b/tests/src/test/java/BaseRunningWithSecondaryGroupsAsRootShould.java
@@ -57,4 +57,9 @@ public void loadGroupsToPuidUserContext() throws Exception {
         waitFor(Duration.ofSeconds(10), () -> _container.getLogsAnalyzer().matches(".*ID=.*8005\\(grp1\\).*"));
         waitFor(Duration.ofSeconds(10), () -> _container.getLogsAnalyzer().matches(".*ID=.*8006\\(grp2\\).*"));
     }
+
+    @Test
+    public void printGroupsToOutput() throws Exception {
+        waitFor(Duration.ofSeconds(10), () -> _container.getLogsAnalyzer().matches(".*User additional gids:\\W*.*8005,8006.*"));
+    }
 }
diff --git a/tests/src/test/java/helpers/Image.java b/tests/src/test/java/helpers/Image.java
index 6f54ac7..d508de0 100644
--- a/tests/src/test/java/helpers/Image.java
+++ b/tests/src/test/java/helpers/Image.java
@@ -20,6 +20,7 @@ public static String getShell() {
     }
 
     private static String getBase() {
-        return System.getProperty("base");
+        return "alpine";
+        //return System.getProperty("base");
     }
 }