diff --git a/scripts/issue-certificate.sh b/scripts/issue-certificate.sh
index 8b35621..aa82e26 100755
--- a/scripts/issue-certificate.sh
+++ b/scripts/issue-certificate.sh
@@ -16,12 +16,12 @@ issue_cert_standalone() {
   docker run -it --rm --name certbot -p 80:80 \
     -v "${1}/etc/letsencrypt:/etc/letsencrypt" \
     -v "${1}/lib/letsencrypt:/var/lib/letsencrypt" \
-    certbot/certbot certonly --standalone -d ${2}
+    certbot/certbot certonly --standalone -d "${2}"
 }
 
 authenticator_to_webroot() {
-  sed -i 's/standalone/webroot/' ${1}/etc/letsencrypt/renewal/${2}.conf
-  tee -a ${1}/etc/letsencrypt/renewal/${2}.conf >/dev/null <<EOF
+  sed -i 's/standalone/webroot/' "${1}"/etc/letsencrypt/renewal/"${2}".conf
+  tee -a "${1}"/etc/letsencrypt/renewal/"${2}".conf >/dev/null <<EOF
 webroot_path = /usr/share/nginx/html,
 [[webroot_map]]
 EOF
@@ -67,10 +67,10 @@ if [ -z "$output" ]; then
   exit 64
 fi
 
-if ! $(which docker 1>/dev/null); then
+if ! which docker 1>/dev/null; then
   echo "Can't find Docker command" >&2
   exit 64
 fi
 
-issue_cert_standalone ${output} ${domain}
-authenticator_to_webroot ${output} ${domain}
+issue_cert_standalone "${output}" "${domain}"
+authenticator_to_webroot "${output}" "${domain}"
diff --git a/scripts/upgrade-from-mattermost-docker.sh b/scripts/upgrade-from-mattermost-docker.sh
index 30c5587..2d43c84 100755
--- a/scripts/upgrade-from-mattermost-docker.sh
+++ b/scripts/upgrade-from-mattermost-docker.sh
@@ -14,9 +14,9 @@ set -o errexit
 #    This may take some time to complete as it's migrating the database to Postgres 13.6 from 9.4
 
 
-PATH_TO_MATTERMOST_DOCKER=$PATH_TO_MATTERMOST_DOCKER # i.e. $PWD
 if [[ $PATH_TO_MATTERMOST_DOCKER == "" ]]; then
-  echo "Please export environment variable PATH_TO_MATTERMOST_DOCKER with '$ export PATH_TO_MATTERMOST_DOCKER=/path/to/mattermost-docker' before running this script. "
+  # shellcheck disable=SC2016
+  echo 'Please export environment variable PATH_TO_MATTERMOST_DOCKER with "$ export PATH_TO_MATTERMOST_DOCKER=/path/to/mattermost-docker", i.e. $PWD before running this script. '
   exit 1
 fi
 
@@ -27,7 +27,7 @@ fi
 # The script is trying to fetch those variables first. Should fetching fail, please export the variables before running the script.
 if [[ $POSTGRES_USER == "" ]]; then
   echo "trying to fetch POSTGRES_USER from $PATH_TO_MATTERMOST_DOCKER/docker-compose.yml"
-  POSTGRES_USER=$(echo "$(grep "^.*-.*POSTGRES_USER=.*$" "$PATH_TO_MATTERMOST_DOCKER"/docker-compose.yml)" | sed s~^.*-.*POSTGRES_USER=~~g)
+  POSTGRES_USER=$(grep "^.*-.*POSTGRES_USER=.*$" "$PATH_TO_MATTERMOST_DOCKER"/docker-compose.yml | sed s~^.*-.*POSTGRES_USER=~~g)
   if [[ $POSTGRES_USER == "" ]]; then
     echo "could not find POSTGRES_USER set in $PATH_TO_MATTERMOST_DOCKER/docker-compose.yml"
     echo "please run 'export POSTGRES_USER=yourPostgresUser' before running this script"
@@ -38,7 +38,7 @@ fi
 
 if [[ $POSTGRES_PASSWORD == "" ]]; then
   echo "trying to fetch POSTGRES_PASSWORD from $PATH_TO_MATTERMOST_DOCKER/docker-compose.yml"
-  POSTGRES_PASSWORD=$(echo "$(grep "^.*-.*POSTGRES_PASSWORD=.*$" "$PATH_TO_MATTERMOST_DOCKER"/docker-compose.yml)" | sed s~^.*-.*POSTGRES_PASSWORD=~~g)
+  POSTGRES_PASSWORD=$(grep "^.*-.*POSTGRES_PASSWORD=.*$" "$PATH_TO_MATTERMOST_DOCKER"/docker-compose.yml | sed s~^.*-.*POSTGRES_PASSWORD=~~g)
   if [[ $POSTGRES_PASSWORD == "" ]]; then
     echo "could not find POSTGRES_PASSWORD set in $PATH_TO_MATTERMOST_DOCKER/docker-compose.yml"
     echo "please run 'export POSTGRES_PASSWORD=yourPostgresPassword' before running this script"
@@ -49,7 +49,7 @@ fi
 
 if [[ $POSTGRES_DB == "" ]]; then
   echo "trying to fetch POSTGRES_DB from $PATH_TO_MATTERMOST_DOCKER/docker-compose.yml"
-  POSTGRES_DB=$(echo "$(grep "^.*-.*POSTGRES_DB=.*$" "$PATH_TO_MATTERMOST_DOCKER"/docker-compose.yml)" | sed s~^.*-.*POSTGRES_DB=~~g)
+  POSTGRES_DB=$(grep "^.*-.*POSTGRES_DB=.*$" "$PATH_TO_MATTERMOST_DOCKER"/docker-compose.yml | sed s~^.*-.*POSTGRES_DB=~~g)
   if [[ $POSTGRES_DB == "" ]]; then
     echo "could not find POSTGRES_DB set in $PATH_TO_MATTERMOST_DOCKER/docker-compose.yml"
     echo "please run 'export POSTGRES_DB=yourPostgresDatabase' before running this script"
@@ -113,7 +113,7 @@ fi
 printf "\n"
 if [[ $MM_OLD_VERSION == "" ]]; then
   echo "trying to fetch MM_OLD_VERSION from $PATH_TO_MATTERMOST_DOCKER/docker-compose.yml"
-  MM_OLD_VERSION=$(echo "$(grep ".*-.*MM_VERSION=.*" "$PATH_TO_MATTERMOST_DOCKER"/docker-compose.yml)" | sed s~.*-.*MM_VERSION=~~g)
+  MM_OLD_VERSION=$(grep ".*-.*MM_VERSION=.*" "$PATH_TO_MATTERMOST_DOCKER"/docker-compose.yml | sed s~.*-.*MM_VERSION=~~g)
   if [[ $MM_OLD_VERSION == "" ]]; then
     echo "could not find MM_OLD_VERSION set in $PATH_TO_MATTERMOST_DOCKER/docker-compose.yml"
     echo "please run 'export MM_OLD_VERSION=yourMMVersion' before running this script"