dpkgs -s instead of dpkg -l

modules/docker.sh

@@ -4,7 +4,8 @@ echo
 echo "  => Docker"
 echo
 
-if [ ! -f /usr/bin/docker ]; then
+dpkg -s docker > /dev/null 2>&1
+if [ $? -ne 0 ]; then
     # Add Docker's official GPG key
     mkdir -p /etc/apt/keyrings
     curl -fsSL https://download.docker.com/linux/debian/gpg | gpg --dearmor -o /etc/apt/keyrings/docker.gpg --yes
@@ -20,4 +21,3 @@ if [ ! -f /usr/bin/docker ]; then
     # Install packages
     apt-get install docker-ce docker-ce-cli containerd.io docker-compose-plugin -y
 fi
-