diff --git a/install-mattermost.sh b/install-mattermost.sh
index c90bdd5..464b89b 100755
--- a/install-mattermost.sh
+++ b/install-mattermost.sh
@@ -9,7 +9,8 @@ conf_file="${working_dir}/conf/mattermost.conf"
 LOCK_DIR="/tmp/$(basename $0).$$.LOCK"
 log_file="${LOCK_DIR}/${script_name%%.*}.log"
 
-backup_date="$(date +%Y-%m-%d-%H%M)"
+backup_date="$(date +%Y-%m-%d-%H%M%S)"
+
 
 
 # ----------
@@ -121,14 +122,14 @@ blank_line() {
 
 detect_os () {
 
-   if $(which lsb_release > /dev/null 2>&1) ; then
+   if command -v lsb_release > /dev/null 2>&1 ; then
 
       DIST="$(lsb_release -i | awk '{print tolower($3)}')"
       DIST_VERSION="$(lsb_release -r | awk '{print tolower($2)}')"
       DIST_CODENAME="$(lsb_release -c | awk '{print tolower($2)}')"
 
       if [[ "$DIST" = "debian" ]]; then
-         if $(echo "$DIST_VERSION" | grep -q '\.') ; then
+         if echo "$DIST_VERSION" | grep -q '\.' ; then
             DIST_VERSION=$(echo "$DIST_VERSION" | cut --delimiter='.' -f1)
          fi
       fi
@@ -209,7 +210,8 @@ DEFAULT_DB_TYPE="pgsql"
 
 # generate random password
 regexp_digit="([23456789].*){2}"
-regexp_special_char="([-_%+].*){2}"
+regexp_special_char="([-_%].*){2}"
+
 regexp_not_alowed="([0ODl18B])"
 LENGTH=16
 
@@ -259,8 +261,8 @@ if [[ -n "$DB_TYPE" ]] ; then
 fi
 
 [[ -n "$DB_NAME" ]] && DEFAULT_DB_NAME="$DB_NAME"
-[[ -n "$DB_USER" ]] && DEFAULT_DB_NAME="$DB_USER"
-[[ -n "$DB_PASS" ]] &&  DEFAULT_DB_PASS="$DB_PASS"
+[[ -n "$DB_USER" ]] && DEFAULT_DB_USER="$DB_USER"
+[[ -n "$DB_PASS" ]] && DEFAULT_DB_PASS="$DB_PASS"
 
 [[ -n "$MATTERMOST_USER" ]] && DEFAULT_MATTERMOST_USER="$MATTERMOST_USER"
 if [[ -n "$MATTERMOST_GROUP" ]]; then
@@ -444,23 +446,35 @@ echo -e "\033[32m--\033[m"
 echo ""
 echo "Enter Database Name used by Mattermost Service"
 echo ""
-if [[ -n "$DEFAULT_DB_NAME" ]]; then
-   while [[ "X${DB_NAME}" = "X" ]]; do
+while true ; do
+
+   if [[ -n "$DEFAULT_DB_NAME" ]]; then
       echononl "Database Name [${DEFAULT_DB_NAME}]: "
-      read DB_NAME
-      if [[ "X${DB_NAME}" = "X" ]]; then
-         DB_NAME=$DEFAULT_DB_NAME
-      fi
-   done
-else
-   while [[ "X${DB_NAME}" = "X" ]]; do
+   else
       echononl "Database Name: "
-      read DB_NAME
-      if [[ "X${DB_NAME}" = "X" ]]; then
-         echo -e "\n\t\033[33m\033[1m Database Name is reqired\033[m\n"
-      fi
-   done
-fi
+   fi
+
+   read DB_NAME
+
+   if [[ -z "$DB_NAME" ]] && [[ -n "$DEFAULT_DB_NAME" ]]; then
+      DB_NAME="$DEFAULT_DB_NAME"
+   fi
+
+   if [[ -z "$DB_NAME" ]]; then
+      echo -e "\n\t\033[33m\033[1mDatabase Name is required.\033[m\n"
+      continue
+   fi
+
+   if [[ ! "$DB_NAME" =~ ^[a-zA-Z0-9_]+$ ]] ; then
+      echo -e "\n\t\033[33m\033[1mDatabase Name contains unsupported characters."
+      echo -e "\tAllowed characters are: a-z A-Z 0-9 _"
+      echo -e "\tPlease enter the database name again.\033[m\n"
+      continue
+   fi
+
+   break
+
+done
 
 DB_USER=
 echo ""
@@ -468,23 +482,35 @@ echo -e "\033[32m--\033[m"
 echo ""
 echo "Enter Database User used by Mattermost Service"
 echo ""
-if [[ -n "$DEFAULT_DB_USER" ]]; then
-   while [[ "X${DB_USER}" = "X" ]]; do
+while true ; do
+
+   if [[ -n "$DEFAULT_DB_USER" ]]; then
       echononl "Database User [${DEFAULT_DB_USER}]: "
-      read DB_USER
-      if [[ "X${DB_USER}" = "X" ]]; then
-         DB_USER=$DEFAULT_DB_USER
-      fi
-   done
-else
-   while [[ "X${DB_USER}" = "X" ]]; do
+   else
       echononl "Database User: "
-      read DB_USER
-      if [[ "X${DB_USER}" = "X" ]]; then
-         echo -e "\n\t\033[33m\033[1m Database User is reqired\033[m\n"
-      fi
-   done
-fi
+   fi
+
+   read DB_USER
+
+   if [[ -z "$DB_USER" ]] && [[ -n "$DEFAULT_DB_USER" ]]; then
+      DB_USER="$DEFAULT_DB_USER"
+   fi
+
+   if [[ -z "$DB_USER" ]]; then
+      echo -e "\n\t\033[33m\033[1mDatabase User is required.\033[m\n"
+      continue
+   fi
+
+   if [[ ! "$DB_USER" =~ ^[a-zA-Z0-9_]+$ ]] ; then
+      echo -e "\n\t\033[33m\033[1mDatabase User contains unsupported characters."
+      echo -e "\tAllowed characters are: a-z A-Z 0-9 _"
+      echo -e "\tPlease enter the database user again.\033[m\n"
+      continue
+   fi
+
+   break
+
+done
 
 DB_PASS=
 echo ""
@@ -492,27 +518,41 @@ echo -e "\033[32m--\033[m"
 echo ""
 echo "Enter Database Password used by Mattermost Service"
 echo ""
-if [[ -n "$DEFAULT_DB_PASS" ]]; then
-   while [[ "X${DB_PASS}" = "X" ]]; do
-      echononl "Database Password [${DEFAULT_DB_PASS}]: "
-      read DB_PASS
-      if [[ "X${DB_PASS}" = "X" ]]; then
-         DB_PASS=$DEFAULT_DB_PASS
-      fi
-   done
-else
-   while [[ "X${DB_PASS}" = "X" ]]; do
+while true ; do
+
+   if [[ -n "$DEFAULT_DB_PASS" ]]; then
+      echononl "Database Password [********]: "
+   else
       echononl "Database Password: "
-      read DB_PASS
-      if [[ "X${DB_PASS}" = "X" ]]; then
-         echo -e "\n\t\033[33m\033[1m Database Password is reqired\033[m\n"
-      fi
-   done
-fi
+   fi
+ 
+   read -s DB_PASS
+   echo
+
+   if [[ -z "$DB_PASS" ]] && [[ -n "$DEFAULT_DB_PASS" ]]; then
+      DB_PASS="$DEFAULT_DB_PASS"
+   fi
+
+   if [[ -z "$DB_PASS" ]]; then
+      echo -e "\n\t\033[33m\033[1mDatabase Password is required.\033[m\n"
+      continue
+   fi
+
+   if [[ ! "$DB_PASS" =~ ^[a-zA-Z1-9_%-]+$ ]] ; then
+      echo -e "\n\t\033[33m\033[1mDatabase Password contains unsupported characters."
+      echo -e "\tAllowed characters are: a-z A-Z 1-9 - _ %"
+      echo -e "\tPlease enter the password again.\033[m\n"
+      continue
+   fi
+
+   break
+
+done
+
 
 if [[ "$DB_TYPE" = "mysql" ]] ; then
    if [[ -n "$MYSQL_CREDENTIAL_ARGS" ]] ; then
-      if ! $(mysql $MYSQL_CREDENTIAL_ARGS -N -s -e 'quit' > /dev/null 2>&1) ; then
+      if ! mysql $MYSQL_CREDENTIAL_ARGS -N -s -e 'quit' > /dev/null 2>&1 ; then
          fatal "Parameter MYSQL_CREDENTIAL_ARGS is given, but a connection to MySQL Service failed.!"
       fi
       USE_MYSQL_CREDENTIAL_ARGS=true
@@ -533,8 +573,8 @@ if [[ "$DB_TYPE" = "mysql" ]] ; then
             echo -e "\n\t\033[33m\033[1mPassworteingabe erforderlich!\033[m\n"
             continue
          fi
-         if $(pgrep mysqld_safe > /dev/null 2>&1) || $(pgrep mysqld > /dev/null 2>&1); then
-            if $(mysql --user="root" --password="$_MYSQL_ROOT_PW"  -N -s -e 'quit' > /dev/null 2>&1) ; then
+         if pgrep mysqld_safe > /dev/null 2>&1 || pgrep mysqld > /dev/null 2>&1 ; then
+            if mysql --user="root" --password="$_MYSQL_ROOT_PW" -N -s -e 'quit' > /dev/null 2>&1 ; then
                MYSQL_ROOT_PW=$_MYSQL_ROOT_PW
             else
                echo -e "\n\t\033[33m\033[1mFalsches Passwort\033[m\n"
@@ -570,7 +610,7 @@ fi
 echo ""
 if [[ "${DB_TYPE}" = "mysql" ]]; then
    if $USE_MYSQL_CREDENTIAL_ARGS ; then
-      echo -e "\tMYSQL_CREDENTIAL_ARGS....: $MYSQL_CREDENTIAL_ARGS"
+      echo -e "\tMYSQL_CREDENTIAL_ARGS....: **"
    else
       echo -e "\tRoot password MySQL......: **"
    fi
@@ -578,7 +618,7 @@ if [[ "${DB_TYPE}" = "mysql" ]]; then
 fi
 echo -e "\tDatabase Name............: $DB_NAME"
 echo -e "\tDatabase User............: $DB_USER"
-echo -e "\tDatabase Password........: $DB_PASS"
+echo -e "\tDatabase Password........: **"
 echo ""
 echononl "einverstanden (yes/no): "
 read OK
@@ -595,8 +635,8 @@ echo ""
 
 
 if ! $USE_MYSQL_CREDENTIAL_ARGS ; then
-   MYSQL_CREDENTIAL_ARGS="--user='root' --password=$_MYSQL_ROOT_PW"
-   if ! $(mysql $MYSQL_CREDENTIAL_ARGS -N -s -e 'quit' > /dev/null 2>&1) ; then
+   MYSQL_CREDENTIAL_ARGS="--user=root --password=$_MYSQL_ROOT_PW"
+   if ! mysql $MYSQL_CREDENTIAL_ARGS -N -s -e 'quit' > /dev/null 2>&1 ; then
       fatal "Parameter MYSQL_CREDENTIAL_ARGS is given, but a connection to MySQL Service failed.!"
    fi
 fi
@@ -609,9 +649,9 @@ echo
 
 _failed=false
 echononl "Check if Nginx Webservice is installed.."
-if $(dpkg -s nginx-extras > "$log_file" 2>&1) ; then
+if dpkg -s nginx-extras > "$log_file" 2>&1 ; then
    nginx_installed=true
-elif $(dpkg -s nginx-full > "$log_file" 2>&1) ; then
+elif dpkg -s nginx-full > "$log_file" 2>&1 ; then
    nginx_installed=true
 else
    nginx_installed=false
@@ -625,7 +665,7 @@ else
    echononl "\033[1mcontinue anyway\033[m [yes/no]: "
    read OK
    while [[ "${OK,,}" != "yes" ]] && [[  "${OK,,}" != "no" ]] ; do
-      echononl "Wrong entry! - repeat [yes/nno]: "
+      echononl "Wrong entry! - repeat [yes/no]: "
       read OK
    done
    [[ $OK = "yes" ]] || fatal "Abbruch durch User"
@@ -634,7 +674,7 @@ fi
 _failed=false
 if [[ "${DB_TYPE}" = "mysql" ]]; then
    echononl "Check if MySQL Database Service is installed.."
-   if $(dpkg -s mysql-server > "$log_file" 2>&1) ; then
+   if dpkg -s mysql-server > "$log_file" 2>&1 ; then
       database_service_installed=true
    else
       database_service_installed=false
@@ -648,14 +688,14 @@ if [[ "${DB_TYPE}" = "mysql" ]]; then
       echononl "\033[1mcontinue anyway\033[m [yes/no]: "
       read OK
       while [[ "${OK,,}" != "yes" ]] && [[  "${OK,,}" != "no" ]] ; do
-         echononl "Wrong entry! - repeat [yes/nno]: "
+         echononl "Wrong entry! - repeat [yes/no]: "
          read OK
       done
       [[ $OK = "yes" ]] || fatal "Abbruch durch User"
    fi
 else
    echononl "Check if PostgreSQL Database Service is installed.."
-   if $(dpkg -s postgresql > "$log_file" 2>&1) ; then
+   if dpkg -s postgresql > "$log_file" 2>&1 ; then
       database_service_installed=true
    else
       database_service_installed=false
@@ -669,7 +709,7 @@ else
       echononl "\033[1mcontinue anyway\033[m [yes/no]: "
       read OK
       while [[ "${OK,,}" != "yes" ]] && [[  "${OK,,}" != "no" ]] ; do
-         echononl "Wrong entry! - repeat [yes/nno]: "
+         echononl "Wrong entry! - repeat [yes/no]: "
          read OK
       done
       [[ $OK = "yes" ]] || fatal "Abbruch durch User"
@@ -718,7 +758,7 @@ elif ! $cert_present ; then
    read OK
    OK="$(echo "$OK" | tr '[:upper:]' '[:lower:]')"
    while [[ "$OK" != "yes" ]] && [[  "$OK" != "no" ]] ; do
-      echononl "Wrong entry! - repeat [yes/nno]: "
+      echononl "Wrong entry! - repeat [yes/no]: "
       read OK
    done
    [[ $OK = "yes" ]] || fatal "Abbruch durch User"
@@ -731,7 +771,7 @@ echo -e "\033[37m\033[1mSome pre-installation stuff..\033[m"
 echo
 
 echononl "Stop Mattermost Service.."
-if $(systemctl is-active --quiet service mattermost.service) ; then
+if systemctl is-active --quiet mattermost.service ; then
    systemctl stop mattermost.service > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -747,19 +787,26 @@ blank_line
 
 
 if [[ "${DB_TYPE}" = "mysql" ]] ; then
-   echononl "Create MySQL Database User '${DB_USER}' with Password '${DB_PASS}'.."
-   if [[ "$(mysql $MYSQL_CREDENTIAL_ARGS  -N -s -e \
-            "SELECT EXISTS(SELECT 1 FROM mysql.user WHERE user = '$DB_USER')" 2>/dev/null)" = 1 ]]; then
-      echo_skipped
+   if [[ "$(mysql $MYSQL_CREDENTIAL_ARGS -N -s -e \
+         "SELECT EXISTS(SELECT 1 FROM mysql.user WHERE user = '$DB_USER' AND host = 'localhost')" 2>/dev/null)" = 1 ]]; then
+
+      echononl "Update password for MySQL Database User '${DB_USER}'@'localhost'.."
+      mysql $MYSQL_CREDENTIAL_ARGS -N -s -e \
+         "ALTER USER '$DB_USER'@'localhost' IDENTIFIED BY '${DB_PASS}'" > "$log_file" 2>&1
+
    else
-      mysql $MYSQL_CREDENTIAL_ARGS  -N -s -e \
+
+      echononl "Create MySQL Database User '${DB_USER}'@'localhost'.."
+      mysql $MYSQL_CREDENTIAL_ARGS -N -s -e \
          "CREATE USER '$DB_USER'@'localhost' IDENTIFIED BY '${DB_PASS}'" > "$log_file" 2>&1
-      if [[ $? -ne 0 ]]; then
-         echo_failed
-         error "$(cat "$log_file")"
-      else
-         echo_ok
-      fi
+
+   fi
+
+   if [[ $? -ne 0 ]]; then
+      echo_failed
+      error "$(cat "$log_file")"
+   else
+      echo_ok
    fi
 
    echononl "Create MySQL Database '${DB_NAME}'.."
@@ -787,37 +834,37 @@ if [[ "${DB_TYPE}" = "mysql" ]] ; then
       echo_ok
    fi
 
-   echononl "FLUSH PRIVILEGES to dadabase engine .."
-   mysql $MYSQL_CREDENTIAL_ARGS  -N -s -e \
-      "FLUSH PRIVILEGES" > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
 else
 
    # Check if PostgreSQL database '$DB_NAME' exists ..
    #
-   count=$(su - postgres -c "psql -q -A -t -l" | grep -c -e "^$DB_NAME")
+   count=$(runuser -u postgres -- psql -q -A -t -d postgres -c "SELECT COUNT(*) FROM pg_database WHERE datname = '${DB_NAME}';")
    if [[ $count -eq 0 ]];then
       database_exists=false
    else
       database_exists=true
    fi
 
-#   sudo -u postgres psql -c "CREATE DATABASE ${DB_NAME};" > $log_file 2>&1
-#   sudo -u postgres psql -c "CREATE USER ${DB_USER} WITH PASSWORD '${DB_PASS}';" > $log_file 2>&1
-#   sudo -u postgres psql -c "GRANT ALL PRIVILEGES ON DATABASE ${DB_NAME} to ${DB_USER};" > $log_file 2>&1
-#   sudo -u postgres psql -c "ALTER DATABASE ${DB_NAME} OWNER TO ${DB_USER};" > $log_file 2>&1
-#   sudo -u postgres psql -c "GRANT USAGE, CREATE ON SCHEMA PUBLIC TO ${DB_USER};" > $log_file 2>&1
+   # Check if PostgreSQL database user '$DB_USER' exists ..
+   #
+   count=$(runuser -u postgres -- psql -q -A -t -d postgres -c "SELECT COUNT(*) FROM pg_roles WHERE rolname = '${DB_USER}';")
+   if [[ $count -eq 0 ]]; then
+      database_user_exists=false
+   else
+      database_user_exists=true
+   fi
+
+#   runuser -u postgres -- psql -c "CREATE DATABASE ${DB_NAME};" > $log_file 2>&1
+#   runuser -u postgres -- psql -c "CREATE USER ${DB_USER} WITH PASSWORD '${DB_PASS}';" > $log_file 2>&1
+#   runuser -u postgres -- psql -c "GRANT ALL PRIVILEGES ON DATABASE ${DB_NAME} to ${DB_USER};" > $log_file 2>&1
+#   runuser -u postgres -- psql -c "ALTER DATABASE ${DB_NAME} OWNER TO ${DB_USER};" > $log_file 2>&1
+#   runuser -u postgres -- psql -c "GRANT USAGE, CREATE ON SCHEMA PUBLIC TO ${DB_USER};" > $log_file 2>&1
 
    echononl "Create PostgreSQL database '${DB_NAME}'.."
    if $database_exists ; then
       echo_skipped
    else
-      sudo -u postgres psql -c "CREATE DATABASE ${DB_NAME};" > $log_file 2>&1
+      runuser -u postgres -- psql -c "CREATE DATABASE ${DB_NAME};" > $log_file 2>&1
 
       if [[ $? -ne 0 ]] ; then
          echo_failed
@@ -827,7 +874,7 @@ else
          echononl "\033[1mcontinue anyway\033[m [yes/no]: "
          read OK
          while [[ "${OK,,}" != "yes" ]] && [[  "${OK,,}" != "no" ]] ; do
-            echononl "Wrong entry! - repeat [yes/nno]: "
+            echononl "Wrong entry! - repeat [yes/no]: "
             read OK
          done
          [[ $OK = "yes" ]] || fatal "Abbruch durch User"
@@ -838,104 +885,89 @@ else
       
    fi
 
-   echononl "Create PostgreSQL database user ${DB_USER}.."
-   if $database_exists ; then
-      echo_skipped
+   if $database_user_exists ; then
+      echononl "Update password for PostgreSQL database user ${DB_USER}.."
+      runuser -u postgres -- psql -c "ALTER USER ${DB_USER} WITH PASSWORD '${DB_PASS}';" > "$log_file" 2>&1
    else
+      echononl "Create PostgreSQL database user ${DB_USER}.."
+      runuser -u postgres -- psql -c "CREATE USER ${DB_USER} WITH PASSWORD '${DB_PASS}';" > "$log_file" 2>&1
+   fi
 
-      sudo -u postgres psql -c "CREATE USER ${DB_USER} WITH PASSWORD '${DB_PASS}';"  > $log_file 2>&1
+   if [[ $? -ne 0 ]] ; then
+      echo_failed
+      error "$(cat "$log_file")"
 
-      if [[ $? -ne 0 ]] ; then
-         echo_failed
-         error "$(cat "$log_file")"
-
-         echo ""
-         echononl "\033[1mcontinue anyway\033[m [yes/no]: "
+      echo ""
+      echononl "\033[1mcontinue anyway\033[m [yes/no]: "
+      read OK
+      while [[ "${OK,,}" != "yes" ]] && [[ "${OK,,}" != "no" ]] ; do
+         echononl "Wrong entry! - repeat [yes/no]: "
          read OK
-         while [[ "${OK,,}" != "yes" ]] && [[  "${OK,,}" != "no" ]] ; do
-            echononl "Wrong entry! - repeat [yes/nno]: "
-            read OK
-         done
-         [[ $OK = "yes" ]] || fatal "Abbruch durch User"
+      done
+      [[ $OK = "yes" ]] || fatal "Abbruch durch User"
 
-      else
-         echo_ok
-      fi
+   else
+      echo_ok
    fi
 
    echononl "Grant the user access to the Mattermost database.."
-   if $database_exists ; then
-      echo_skipped
-   else
+   runuser -u postgres -- psql -c "GRANT ALL PRIVILEGES ON DATABASE ${DB_NAME} TO ${DB_USER};" > "$log_file" 2>&1
 
-      sudo -u postgres psql -c "GRANT ALL PRIVILEGES ON DATABASE ${DB_NAME} to ${DB_USER};" > $log_file 2>&1
+   if [[ $? -ne 0 ]] ; then
+      echo_failed
+      error "$(cat "$log_file")"
 
-      if [[ $? -ne 0 ]] ; then
-         echo_failed
-         error "$(cat "$log_file")"
-
-         echo ""
-         echononl "\033[1mcontinue anyway\033[m [yes/no]: "
+      echo ""
+      echononl "\033[1mcontinue anyway\033[m [yes/no]: "
+      read OK
+      while [[ "${OK,,}" != "yes" ]] && [[ "${OK,,}" != "no" ]] ; do
+         echononl "Wrong entry! - repeat [yes/no]: "
          read OK
-         while [[ "${OK,,}" != "yes" ]] && [[  "${OK,,}" != "no" ]] ; do
-            echononl "Wrong entry! - repeat [yes/nno]: "
-            read OK
-         done
-         [[ $OK = "yes" ]] || fatal "Abbruch durch User"
+      done
+      [[ $OK = "yes" ]] || fatal "Abbruch durch User"
 
-      else
-         echo_ok
-      fi
+   else
+      echo_ok
    fi
 
    echononl "Change the owner of database '${DB_NAME}' to '${DB_USER}'.."
-   if $database_exists ; then
-      echo_skipped
-   else
+   runuser -u postgres -- psql -c "ALTER DATABASE ${DB_NAME} OWNER TO ${DB_USER};" > "$log_file" 2>&1
 
-      sudo -u postgres psql -c "ALTER DATABASE ${DB_NAME} OWNER TO ${DB_USER};" > $log_file 2>&1
+   if [[ $? -ne 0 ]] ; then
+      echo_failed
+      error "$(cat "$log_file")"
 
-      if [[ $? -ne 0 ]] ; then
-         echo_failed
-         error "$(cat "$log_file")"
-
-         echo ""
-         echononl "\033[1mcontinue anyway\033[m [yes/no]: "
+      echo ""
+      echononl "\033[1mcontinue anyway\033[m [yes/no]: "
+      read OK
+      while [[ "${OK,,}" != "yes" ]] && [[ "${OK,,}" != "no" ]] ; do
+         echononl "Wrong entry! - repeat [yes/no]: "
          read OK
-         while [[ "${OK,,}" != "yes" ]] && [[  "${OK,,}" != "no" ]] ; do
-            echononl "Wrong entry! - repeat [yes/nno]: "
-            read OK
-         done
-         [[ $OK = "yes" ]] || fatal "Abbruch durch User"
+      done
+      [[ $OK = "yes" ]] || fatal "Abbruch durch User"
 
-      else
-         echo_ok
-      fi
+   else
+      echo_ok
    fi
 
    echononl "Grant access to objects contained in the specified schema.."
-   if $database_exists ; then
-      echo_skipped
-   else
+   runuser -u postgres -- psql -d "${DB_NAME}" -c "GRANT USAGE, CREATE ON SCHEMA PUBLIC TO ${DB_USER};" > "$log_file" 2>&1
 
-      sudo -u postgres psql -c "GRANT USAGE, CREATE ON SCHEMA PUBLIC TO ${DB_USER};" > $log_file 2>&1
+   if [[ $? -ne 0 ]] ; then
+      echo_failed
+      error "$(cat "$log_file")"
 
-      if [[ $? -ne 0 ]] ; then
-         echo_failed
-         error "$(cat "$log_file")"
-
-         echo ""
-         echononl "\033[1mcontinue anyway\033[m [yes/no]: "
+      echo ""
+      echononl "\033[1mcontinue anyway\033[m [yes/no]: "
+      read OK
+      while [[ "${OK,,}" != "yes" ]] && [[ "${OK,,}" != "no" ]] ; do
+         echononl "Wrong entry! - repeat [yes/no]: "
          read OK
-         while [[ "${OK,,}" != "yes" ]] && [[  "${OK,,}" != "no" ]] ; do
-            echononl "Wrong entry! - repeat [yes/nno]: "
-            read OK
-         done
-         [[ $OK = "yes" ]] || fatal "Abbruch durch User"
+      done
+      [[ $OK = "yes" ]] || fatal "Abbruch durch User"
 
-      else
-         echo_ok
-      fi
+   else
+      echo_ok
    fi
 
 fi
@@ -976,7 +1008,8 @@ if [[ ! -f "${working_dir}/${DOWNLOAD_ARCHIVE}" ]]; then
    wget -O "${working_dir}/${DOWNLOAD_ARCHIVE}" "${DOWNLOAD_URL}" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
-      error "$(cat "$log_file")"
+      rm -f "${working_dir}/${DOWNLOAD_ARCHIVE}"
+      fatal "$(cat "$log_file")"
    else
       echo_ok
    fi
@@ -984,14 +1017,32 @@ else
    echo_skipped
 fi
 
+echononl "Check Mattermost Server archive.."
+if tar -tzf "${working_dir}/${DOWNLOAD_ARCHIVE}" > /dev/null 2> "$log_file" ; then
+   echo_ok
+else
+   echo_failed
+   rm -f "${working_dir}/${DOWNLOAD_ARCHIVE}"
+   fatal "Mattermost Server archive is invalid or incomplete. Please run the installation again."
+fi
+
 echononl "Backup Mattermost Installation directory.."
 if [[ -d "/opt/mattermost" ]]; then
    cp -a "/opt/mattermost" "/opt/mattermost.${backup_date}" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
-      error "$(cat "$log_file")"
+      fatal "$(cat "$log_file")"
    else
       echo_ok
+
+      echononl "Remove existing Mattermost Installation directory.."
+      rm -rf "/opt/mattermost" > "$log_file" 2>&1
+      if [[ $? -ne 0 ]]; then
+         echo_failed
+         fatal "$(cat "$log_file")"
+      else
+         echo_ok
+      fi
    fi
 else
    echo_skipped
@@ -1001,12 +1052,29 @@ echononl "Extract the Mattermost Server files.."
 tar -C /opt -xvzf "${working_dir}/${DOWNLOAD_ARCHIVE}" > "$log_file" 2>&1
 if [[ $? -ne 0 ]]; then
    echo_failed
-   error "$(cat "$log_file")"
+   fatal "$(cat "$log_file")"
 else
    echo_ok
 fi
 
-echononl "Set ownbership of installation directors '/opt/mattermost'.."
+echononl "Verify Mattermost Edition.."
+if [[ "$MATTERMOST_EDITION" == "enterprise" ]]; then
+   if /opt/mattermost/bin/mattermost version 2>&1 | grep -q "Build Enterprise Ready: true"; then
+      echo_ok
+   else
+      echo_failed
+      fatal "Downloaded Mattermost binary is not Enterprise Ready."
+   fi
+else
+   if /opt/mattermost/bin/mattermost version 2>&1 | grep -q "Build Enterprise Ready: false"; then
+      echo_ok
+   else
+      echo_failed
+      fatal "Downloaded Mattermost binary is not Team Edition."
+   fi
+fi
+
+echononl "Set ownership of installation directory '/opt/mattermost'.."
 chown -R ${MATTERMOST_USER}:${MATTERMOST_GROUP} /opt/mattermost > "$log_file" 2>&1
 if [[ $? -ne 0 ]]; then
    echo_failed
@@ -1016,7 +1084,7 @@ else
 fi
 
 echononl "Give write permissions to the mattermost group.."
-chmod -R g+w /opt/mattermost> "$log_file" 2>&1
+chmod -R g+w /opt/mattermost > "$log_file" 2>&1
 if [[ $? -ne 0 ]]; then
    echo_failed
    error "$(cat "$log_file")"
@@ -1044,7 +1112,9 @@ echo
 
 echononl "Set up 'SqlSettings'.."
 if  [[ "${DB_TYPE}" = "mysql" ]] ; then
-   if ! $(grep -q -E "^\s*\"DriverName\":\s+mysql" /opt/mattermost/config/config.json 2> "$log_file") ; then
+   if ! grep -q -E "^\s*\"DriverName\":\s+\"mysql\"" /opt/mattermost/config/config.json 2> "$log_file" \
+      || ! grep -Fq "\"DataSource\": \"${DB_USER}:${DB_PASS}@tcp(localhost:3306)/${DB_NAME}?charset=utf8mb4,utf8\\u0026readTimeout=30s\\u0026writeTimeout=30s\"," \
+         /opt/mattermost/config/config.json 2> "$log_file" ; then
 
       _found=false
       :> ${LOCK_DIR}/config.json
@@ -1088,7 +1158,10 @@ EOF
       echo_skipped
    fi
 else
-   if ! $(grep -q -E "^\s*\"DriverName\":\s+postgres" /opt/mattermost/config/config.json 2> "$log_file") ; then
+   if ! grep -q -E "^\s*\"DriverName\":\s+\"postgres\"" /opt/mattermost/config/config.json 2> "$log_file" \
+      || ! grep -Fq "\"DataSource\": \"postgres://${DB_USER}:${DB_PASS}@localhost:5432/${DB_NAME}?sslmode=disable\\u0026connect_timeout=10\"," \
+         /opt/mattermost/config/config.json 2> "$log_file" ; then
+
 
       _found=false
       :> ${LOCK_DIR}/config.json
@@ -1136,7 +1209,9 @@ fi
 
 
 echononl "Set up 'ServiceSettings'.."
-if ! $(grep -q -E "^\s*\"SiteURL\":\s+\"https://${FQHN_HOSTNAME}\"" /opt/mattermost/config/config.json 2> "$log_file") ; then
+if ! grep -q -E "^\s*\"SiteURL\":\s+\"https://${FQHN_HOSTNAME}\"" /opt/mattermost/config/config.json 2> "$log_file" \
+   || ! grep -q -E "^\s*\"ListenAddress\":\s+\"127\.0\.0\.1:8065\"" /opt/mattermost/config/config.json 2> "$log_file" ; then
+
 
    _found=false
    :> ${LOCK_DIR}/config.json
@@ -1180,7 +1255,7 @@ else
    echo_skipped
 fi
 
-echononl "Reset ownbership of '/opt/mattermost/config/config.json'.."
+echononl "Reset ownership of '/opt/mattermost/config/config.json'.."
 chown ${MATTERMOST_USER}:${MATTERMOST_GROUP} /opt/mattermost/config/config.json > "$log_file" 2>&1
 if [[ $? -ne 0 ]]; then
    echo_failed
@@ -1196,13 +1271,10 @@ echo -e "\033[37m\033[1mSetup Mattermost to use systemd for starting and stoppin
 echo
 
 echononl "Create a systemd unit file.."
-if [[ "${DB_TYPE}" = "mysql" ]] ; then
-   cat <<EOF > /etc/systemd/system//mattermost.service 2>"$log_file"
+cat <<EOF > /etc/systemd/system/mattermost.service 2>"$log_file"
 [Unit]
 Description=Mattermost
 After=network.target
-After=mysql.service
-Requires=mysql.service
 
 [Service]
 Type=notify
@@ -1219,40 +1291,12 @@ LimitNOFILE=524288
 [Install]
 WantedBy=multi-user.target
 EOF
-   if [[ -s "$log_file" ]] ; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
+
+if [[ -s "$log_file" ]] ; then
+   echo_failed
+   error "$(cat "$log_file")"
 else
-   cat <<EOF > /etc/systemd/system//mattermost.service 2>"$log_file"
-[Unit]
-Description=Mattermost
-After=network.target
-
-[Service]
-Type=notify
-ExecStart=/opt/mattermost/bin/mattermost
-TimeoutStartSec=3600
-KillMode=mixed
-Restart=always
-RestartSec=10
-WorkingDirectory=/opt/mattermost
-User=mattermost
-Group=mattermost
-LimitNOFILE=49152
-
-[Install]
-WantedBy=multi-user.target
-EOF
-
-   if [[ -s "$log_file" ]] ; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
+   echo_ok
 fi
 
 
@@ -1351,11 +1395,8 @@ server {
    # Enable TLS versions (TLSv1.3 is required upcoming HTTP/3 QUIC).
    ssl_protocols TLSv1.2 TLSv1.3;
 
-   # Enable TLSv1.3's 0-RTT. Use \$ssl_early_data when reverse proxying to
-   # prevent replay attacks.
-   #
-   # @see: https://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_early_data
-   ssl_early_data on;
+   # TLSv1.3 0-RTT is intentionally disabled to avoid replay risks.
+   ssl_early_data off;
 
    # ECDHE better than DHE (faster)  ECDHE & DHE GCM better than CBC (attacks on AES)
    # Everything better than SHA1 (deprecated)
@@ -1375,7 +1416,6 @@ server {
    # HSTS (ngx_http_headers_module is required) (15768000 seconds = 6 months)
    #
    add_header Strict-Transport-Security max-age=15768000;
-   add_header X-Early-Data \$tls1_3_early_data;
    add_header X-Frame-Options SAMEORIGIN;
 
    # OCSP Stapling deaktiviert: Let's Encrypt hat seinen OCSP-Dienst am
@@ -1428,14 +1468,6 @@ server {
    }
 }
 
-# This block is useful for debugging TLS v1.3. Please feel free to remove this
-# and use the '\$ssl_early_data' variable exposed by NGINX directly should you
-# wish to do so.
-map \$ssl_early_data \$tls1_3_early_data {
-  "~." \$ssl_early_data;
-  default "";
-}
-
 EOF
 if [[ $? -ne 0 ]]; then
    echo_failed
@@ -1458,13 +1490,22 @@ else
    echo_skipped
 fi
 
-echononl "Restart NGINX Service.."
-systemctl restart nginx  > "$log_file" 2>&1
+echononl "Test NGINX configuration.."
+nginx -t > "$log_file" 2>&1
 if [[ $? -ne 0 ]]; then
    echo_failed
    error "$(cat "$log_file")"
 else
    echo_ok
+
+   echononl "Restart NGINX Service.."
+   systemctl restart nginx > "$log_file" 2>&1
+   if [[ $? -ne 0 ]]; then
+      echo_failed
+      error "$(cat "$log_file")"
+   else
+      echo_ok
+   fi
 fi
 
 echo ""
@@ -1488,9 +1529,11 @@ fi
 _key="FQHN_HOSTNAME"
 _val="$FQHN_HOSTNAME"
 echononl "Update Parameter '$_key'.."
-if $(grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null) ; then
+if grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null ; then
+
    echo_skipped
-elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null ; then
+
    perl -i -n -p -e "s/^\s*$_key=.*/${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1498,7 +1541,8 @@ elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
    else
       echo_ok
    fi
-elif $(grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null ; then
+
    perl -i -n -p -e "s/^(\s*\#\s*$_key=.*)/\1\n${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1523,9 +1567,9 @@ fi
 _key="MATTERMOST_USER"
 _val="$MATTERMOST_USER"
 echononl "Update Parameter '$_key'.."
-if $(grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null) ; then
+if grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null ; then
    echo_skipped
-elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null ; then
    perl -i -n -p -e "s/^\s*$_key=.*/${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1533,7 +1577,7 @@ elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
    else
       echo_ok
    fi
-elif $(grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null ; then
    perl -i -n -p -e "s/^(\s*\#\s*$_key=.*)/\1\n${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1558,9 +1602,10 @@ fi
 _key="MATTERMOST_GROUP"
 _val="$MATTERMOST_GROUP"
 echononl "Update Parameter '$_key'.."
-if $(grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null) ; then
+if grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null ; then
    echo_skipped
-elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null ; then
+
    perl -i -n -p -e "s/^\s*$_key=.*/${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1568,7 +1613,8 @@ elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
    else
       echo_ok
    fi
-elif $(grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null ; then
+
    perl -i -n -p -e "s/^(\s*\#\s*$_key=.*)/\1\n${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1593,9 +1639,9 @@ fi
 _key="DB_TYPE"
 _val="$DB_TYPE"
 echononl "Update Parameter '$_key'.."
-if $(grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null) ; then
+if grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null ; then
    echo_skipped
-elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null ; then
    perl -i -n -p -e "s/^\s*$_key=.*/${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1603,7 +1649,7 @@ elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
    else
       echo_ok
    fi
-elif $(grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null ; then
    perl -i -n -p -e "s/^(\s*\#\s*$_key=.*)/\1\n${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1628,9 +1674,9 @@ fi
 _key="DB_NAME"
 _val="$DB_NAME"
 echononl "Update Parameter '$_key'.."
-if $(grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null) ; then
+if grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null ; then
    echo_skipped
-elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null ; then
    perl -i -n -p -e "s/^\s*$_key=.*/${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1638,7 +1684,7 @@ elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
    else
       echo_ok
    fi
-elif $(grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null ; then
    perl -i -n -p -e "s/^(\s*\#\s*$_key=.*)/\1\n${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1663,9 +1709,9 @@ fi
 _key="DB_USER"
 _val="$DB_USER"
 echononl "Update Parameter '$_key'.."
-if $(grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null) ; then
+if grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null ; then
    echo_skipped
-elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null ; then
    perl -i -n -p -e "s/^\s*$_key=.*/${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1673,7 +1719,7 @@ elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
    else
       echo_ok
    fi
-elif $(grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null ; then
    perl -i -n -p -e "s/^(\s*\#\s*$_key=.*)/\1\n${_key}=\"${_val}\"/" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1698,9 +1744,9 @@ fi
 _key="DB_PASS"
 _val="$DB_PASS"
 echononl "Update Parameter '$_key'.."
-if $(grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null) ; then
+if grep -q -E "^\s*$_key=\"?$_val\"?\s*$" "$conf_file" 2> /dev/null ; then
    echo_skipped
-elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null ; then
    perl -i -n -p -e "s§^\s*$_key=.*§${_key}=\"${_val}\"§" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1708,7 +1754,7 @@ elif $(grep -q -E "^\s*$_key=" "$conf_file" 2> /dev/null) ; then
    else
       echo_ok
    fi
-elif $(grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null) ; then
+elif grep -q -E "^\s*#\s*${_key}" "$conf_file" 2> /dev/null ; then
    perl -i -n -p -e "s&^(\s*\#\s*$_key=.*)&\1\n${_key}=\"${_val}\"&" "$conf_file" > "$log_file" 2>&1
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -1730,288 +1776,14 @@ EOF
 fi
 
 
-
-
-
-clean_up 0
-
-
-echo
-echo -e "\033[37m\033[1mUpdate file '/etc/systemd/system.conf'....\033[m"
-echo
-
-echononl "Set Parameter 'DefaultLimitNOFILE'.."
-if ! $(grep -q -E "^\s*DefaultLimitNOFILE=" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^(\s*#DefaultLimitNOFILE=.*)/\1\nDefaultLimitNOFILE=1048576/" \
-      /etc/systemd/system.conf  > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-elif ! $(grep -q -E "^\s*DefaultLimitNOFILE=1048576" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^\s*DefaultLimitNOFILE=.*/DefaultLimitNOFILE=1048576/" \
-      /etc/systemd/system.conf > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-else
-   echo_skipped
-fi
-
-echononl "Set Parameter 'DefaultLimitNPROC'.."
-if ! $(grep -q -E "^\s*DefaultLimitNPROC=" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^(\s*#DefaultLimitNPROC=.*)/\1\nDefaultLimitNPROC=1048576/" \
-      /etc/systemd/system.conf > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-elif ! $(grep -q -E "^\s*DefaultLimitNPROC=1048576" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^\s*DefaultLimitNPROC=.*/DefaultLimitNPROC=1048576/" \
-      /etc/systemd/system.conf > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-else
-   echo_skipped
-fi
-
-echononl "Set Parameter 'DefaultTasksMax'.."
-if ! $(grep -q -E "^\s*DefaultTasksMax=" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^(\s*#DefaultTasksMax=.*)/\1\nDefaultTasksMax=1048576/" \
-      /etc/systemd/system.conf > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-elif ! $(grep -q -E "^\s*DefaultTasksMax=1048576" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^\s*DefaultTasksMax=.*/DefaultTasksMax=1048576/" \
-      /etc/systemd/system.conf > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-else
-   echo_skipped
-fi
-
-echononl "Set Parameter 'DefaultLimitRTPRIO'.."
-if ! $(grep -q -E "^\s*DefaultLimitRTPRIO=" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^(\s*#DefaultLimitRTPRIO=.*)/\1\nDefaultLimitRTPRIO=infinity/" \
-      /etc/systemd/system.conf > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-elif ! $(grep -q -E "^\s*DefaultLimitRTPRIO=infinity" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^\s*DefaultLimitRTPRIO=.*/DefaultLimitRTPRIO=infinity/" \
-      /etc/systemd/system.conf > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-else
-   echo_skipped
-fi
-
-echononl "Set Parameter 'DefaultLimitRTTIME'.."
-if ! $(grep -q -E "^\s*DefaultLimitRTTIME=" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^(\s*#DefaultLimitRTTIME=.*)/\1\nDefaultLimitRTTIME=infinity/" \
-      /etc/systemd/system.conf > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-elif ! $(grep -q -E "^\s*DefaultLimitRTTIME=infinity" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^\s*DefaultLimitRTTIME=.*/DefaultLimitRTTIME=infinity/" \
-      /etc/systemd/system.conf > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-else
-   echo_skipped
-fi
-
-_failed=false
-echononl "Set Parameter 'DefaultLimitCORE'.."
-if ! $(grep -q -E "^\s*DefaultLimitCORE=" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^(\s*#DefaultLimitCORE=.*)/\1\nDefaultLimitCORE=infinity/" \
-      /etc/systemd/system.conf > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-elif ! $(grep -q -E "^\s*DefaultLimitCORE=infinity" /etc/systemd/system.conf 2> /dev/null); then
-   perl -i -n -p -e "s/^\s*DefaultLimitCORE=.*/DefaultLimitCORE=infinity/" \
-      /etc/systemd/system.conf > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-else
-   echo_skipped
-fi
-
-
-echononl "Reload Systemd .."
-systemctl daemon-reload > "$log_file" 2>&1
-if [[ $? -ne 0 ]]; then
-   echo_failed
-   error "$(cat "$log_file")"
-else
-   echo_ok
-fi
-
-
-echo
-echo -e "\033[37m\033[1mSome Certifikation/Key stuff..\033[m"
-echo
-
-cert_copied=false
-echononl "Copy Snakeoil Cert to file '/etc/ssl/fullchain.pem'.."
-if [[ ! -f "/etc/ssl/fullchain.pem" ]] && [[ ! -h "/etc/ssl/fullchain.pem" ]]; then
-   cp /etc/ssl/certs/ssl-cert-snakeoil.pem /etc/ssl/fullchain.pem > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-      cert_copied=true
-   fi
-else
-   echo_skipped
-fi
-
-perm_cert="644"
-echononl "Set Permission $perm_cert on file '/etc/ssl/fullchain.pem'.."
-if $cert_copied ; then
-   chmod 644 /etc/ssl/fullchain.pem > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-else
-   echo_skipped
-fi
-
-if [[ ! -h "/etc/ssl/${FQHN_HOSTNAME}.crt" ]]; then
-   if [[ -f "/etc/ssl/${FQHN_HOSTNAME}.crt" ]] ; then
-      echononl "Remove file '/etc/ssl/${FQHN_HOSTNAME}.crt'.."
-      rm "/etc/ssl/${FQHN_HOSTNAME}.crt" > "$log_file" 2>&1
-      if [[ $? -ne 0 ]]; then
-         echo_failed
-         error "$(cat "$log_file")"
-      else
-         echo_ok
-      fi
-   fi
-   echononl "Set Symlink '/etc/ssl/${FQHN_HOSTNAME}.crt --> fullchain.pem'.."
-   ln -s fullchain.pem /etc/ssl/${FQHN_HOSTNAME}.crt > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-else
-   echononl "Set Symlink '/etc/ssl/${FQHN_HOSTNAME}.crt --> fullchain.pem'.."
-   echo_skipped
-fi
-
-blank_line
-
-key_copied=false
-echononl "Copy Snakeoil Key to file '/etc/ssl/privkey.pem'.."
-if [[ ! -f "/etc/ssl/privkey.pem" ]] && [[ ! -h "/etc/ssl/privkey.pem" ]]; then
-   cp  /etc/ssl/private/ssl-cert-snakeoil.key /etc/ssl/privkey.pem > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-      key_copied=true
-   fi
-else
-   echo_skipped
-fi
-
-perm_key="644"
-echononl "Set Permission $perm_key on file '/etc/ssl/privkey.pem'.."
-if $key_copied ; then
-   chmod 644 /etc/ssl/privkey.pem > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-else
-   echo_skipped
-fi
-
-if [[ ! -h "/etc/ssl/${FQHN_HOSTNAME}.key" ]]; then
-   if [[ -f "/etc/ssl/${FQHN_HOSTNAME}.key" ]] ; then
-      echononl "Remove file '/etc/ssl/${FQHN_HOSTNAME}.key'.."
-      rm "/etc/ssl/${FQHN_HOSTNAME}.key" > "$log_file" 2>&1
-      if [[ $? -ne 0 ]]; then
-         echo_failed
-         error "$(cat "$log_file")"
-      else
-         echo_ok
-      fi
-   fi
-   echononl "Set Symlink '/etc/ssl/${FQHN_HOSTNAME}.key --> privkey.pem'.."
-   ln -s fullchain.pem /etc/ssl/${FQHN_HOSTNAME}.key > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-else
-   echononl "Set Symlink '/etc/ssl/${FQHN_HOSTNAME}.key --> privkey.pem'.."
-   echo_skipped
-fi
-
-
-
 echo
 echo -e "\033[37m\033[1mSome naming stuff..\033[m"
 echo
 
-echononl "Change /etc/hostname - set entry to '$FQHN_HOSTNAME'.."
-if [[ "$(head -1 /etc/hostname)" != "$FQHN_HOSTNAME" ]]; then
+echononl "Change /etc/hostname - set entry to '$HOSTNAME'.."
+if [[ "$(head -1 /etc/hostname)" != "$HOSTNAME" ]]; then
    cat <<EOF > /etc/hostname
-$FQHN_HOSTNAME
+$HOSTNAME
 EOF
    if [[ $? -ne 0 ]]; then
       echo_failed
@@ -2027,8 +1799,9 @@ blank_line
 
 echo -e "   Take care '/etc/hosts' contains line '127.0.1.1 ${FQHN_HOSTNAME} $HOSTNAME'.."
 echononl "  \033[1m127.0.1.1 ${FQHN_HOSTNAME} $HOSTNAME\033[m .."
-if ! $(grep -q -E "^\s*127.0.1.1 ${FQHN_HOSTNAME} $HOSTNAME" /etc/hosts 2> "$log_file") ; then
-   if $(grep -q -E "^\s*127.0.1.1" /etc/hosts 2> "$log_file") ; then
+if ! grep -q -E "^\s*127.0.1.1 ${FQHN_HOSTNAME} $HOSTNAME" /etc/hosts 2> "$log_file" ; then
+   if grep -q -E "^\s*127.0.1.1" /etc/hosts 2> "$log_file" ; then
+
       perl -i -n -p -e "s/(^\s*127.0.1.1.*)/#\1\n127.0.1.1 ${FQHN_HOSTNAME} $HOSTNAME/" \
          /etc/hosts > "$log_file" 2>&1
       if [[ $? -ne 0 ]]; then
@@ -2037,7 +1810,7 @@ if ! $(grep -q -E "^\s*127.0.1.1 ${FQHN_HOSTNAME} $HOSTNAME" /etc/hosts 2> "$log
       else
          echo_ok
       fi
-   elif $(grep -q -E "^\s*127.0.0.1" /etc/hosts 2> "$log_file") ; then
+   elif grep -q -E "^\s*127.0.0.1" /etc/hosts 2> "$log_file" ; then
       perl -i -n -p -e "s/(^\s*127.0.0.1.*)/\1\n127.0.1.1 ${FQHN_HOSTNAME} $HOSTNAME/" \
          /etc/hosts > "$log_file" 2>&1
       if [[ $? -ne 0 ]]; then
@@ -2064,53 +1837,10 @@ fi
 
 
 echo
-echo -e "\033[37m\033[1mRepository stuff..\033[m"
+echo -e "\033[37m\033[1mInstall optional Mattermost dependencies..\033[m"
 echo
 
-
-echononl "Add the '$JITSI_REPOSITORY_VERSION' Jitsi package repository.."
-echo "deb https://download.jitsi.org ${JITSI_REPOSITORY_VERSION}/" > /etc/apt/sources.list.d/jitsi-${JITSI_REPOSITORY_VERSION}.list
-if [[ $? -ne 0 ]]; then
-   echo_failed
-   error "$(cat "$log_file")"
-else
-   echo_ok
-fi
-
-if [[ "$JITSI_REPOSITORY_VERSION" = "stable" ]]; then
-   if [[ -f "/etc/apt/sources.list.d/jitsi-unstable.list" ]]; then
-      echononl "Remove Repository List for 'unstable' jitsi packages.."
-      rm "/etc/apt/sources.list.d/jitsi-unstable.list" > "$log_file" 2>&1
-      if [[ $? -ne 0 ]]; then
-         echo_failed
-         error "$(cat "$log_file")"
-      else
-         echo_ok
-      fi
-   fi
-else
-   if [[ -f "/etc/apt/sources.list.d/jitsi-stable.list" ]]; then
-      echononl "Remove Repository List for 'stable' jitsi packages.."
-      rm "/etc/apt/sources.list.d/jitsi-stable.list" > "$log_file" 2>&1
-      if [[ $? -ne 0 ]]; then
-         echo_failed
-         error "$(cat "$log_file")"
-      else
-         echo_ok
-      fi
-   fi
-fi
-
-echononl "Add the Jitsi Maintainer gpg key.."
-wget -qO -  https://download.jitsi.org/jitsi-key.gpg.key 2> "$log_file" | sudo apt-key add - > "$log_file" 2>&1
-if [[ $? -ne 0 ]]; then
-   echo_failed
-   error "$(cat "$log_file")"
-else
-   echo_ok
-fi
-
-echononl "Update Repository.."
+echononl "Update package lists.."
 apt-get update > "$log_file" 2>&1
 if [[ $? -ne 0 ]]; then
    echo_failed
@@ -2119,6 +1849,9 @@ else
    echo_ok
 fi
 
+blank_line
+
+
 # Install ffmpeg. Mattermost Agents uses ffmpeg for audio transcription.
 # This is independent of the selected Mattermost edition.
 #
@@ -2154,22 +1887,4 @@ else
 fi
 
 
-# Ensure support is available for apt repositories served via HTTPS
-#
-echononl "Install 'apt-transport-https'.."
-if $(dpkg -s apt-transport-https > "$log_file" 2>&1) ; then
-   echo_skipped
-else
-   apt-get install -y apt-transport-https > "$log_file" 2>&1
-   if [[ $? -ne 0 ]]; then
-      echo_failed
-      error "$(cat "$log_file")"
-   else
-      echo_ok
-   fi
-fi
-
-info "To ensure, your system is fully prepared for installing Jitsi Meet, it is
-             recommend to \033[1mreboot the system before installing Jitsi Meet\033[m."
-
 clean_up 0