diff --git a/scr/3_create_user.sh b/scr/3_create_user.sh
index 2090dcf..270251a 100755
--- a/scr/3_create_user.sh
+++ b/scr/3_create_user.sh
@@ -12,7 +12,7 @@ fi
 this_file_name=`basename "$0"`
 
 if [ $# -ne 1 ]; then
-    echo usage: $this_file_name [USERNAME]
+    echo usage: ${this_file_name} [USERNAME]
     exit 1
 fi
 
@@ -21,8 +21,8 @@ username=$1
 # ---
 # create a new non-root user
 # ---
-adduser --disabled-password --gecos "" $username
-mkdir /home/$username/.ssh
-cp /root/.ssh/authorized_keys /home/$username/.ssh/
-chown $username:$username /home/$username/.ssh/
-chown $username:$username /home/$username/.ssh/authorized_keys
+adduser --disabled-password --gecos "" ${username}
+mkdir /home/${username}/.ssh
+cp /root/.ssh/authorized_keys /home/${username}/.ssh/
+chown ${username}:${username} /home/${username}/.ssh/
+chown ${username}:${username} /home/${username}/.ssh/authorized_keys
diff --git a/scr/4_acmesh.sh b/scr/4_acmesh.sh
index 4523555..72db623 100755
--- a/scr/4_acmesh.sh
+++ b/scr/4_acmesh.sh
@@ -12,7 +12,7 @@ fi
 this_file_name=`basename "$0"`
 
 if [ $# -ne 1 ]; then
-    echo usage: $this_file_name [E-MAIL]
+    echo usage: ${this_file_name} [E-MAIL]
     exit 1
 fi
 
@@ -25,7 +25,7 @@ apt -y install git-core bc
 cd /tmp/
 git clone https://github.com/acmesh-official/acme.sh.git
 cd acme.sh/
-./acme.sh --install -m $email
+./acme.sh --install -m ${email}
 
 # ---
 # manual steps
diff --git a/scr/6_add_www_root.sh b/scr/6_add_www_root.sh
index 53086ba..50186ab 100755
--- a/scr/6_add_www_root.sh
+++ b/scr/6_add_www_root.sh
@@ -12,12 +12,14 @@ fi
 this_file_name=`basename "$0"`
 
 if [ $# -ne 2 ]; then
-    echo usage: $this_file_name [USERNAME] [BARE_DOMAIN]
+    echo usage: ${this_file_name} [USERNAME] [BARE_DOMAIN]
     exit 1
 fi
 
 username=$1
 domain=$2
 
-mkdir -p /var/www/$domain
-chown $username:$username /var/www/$domain
+mkdir -p /var/www/${domain}
+chown ${username}:${username} /var/www/${domain}
+
+echo "created directory '/var/www/${domain}'"