diff --git a/runner_scripts/root/cleanup.sh b/runner_scripts/root/cleanup.sh
index 6e6421d502c8f167737629922686f49dd2ebb5ea..93a0630a62fcc3250c923d8dc5706d1516436d11 100755
--- a/runner_scripts/root/cleanup.sh
+++ b/runner_scripts/root/cleanup.sh
@@ -25,8 +25,8 @@ function error {
 
 ## User authentication
 
-: "${CUSTOM_ENV_AUTH_USER:?"AUTH_USER CI/CD variable has not been set."}"
-: "${CUSTOM_ENV_AUTH_KEY:?"AUTH_KEY CI/CD variable has not been set."}"
+[ -z "$CUSTOM_ENV_AUTH_USER" ] && error "AUTH_USER CI/CD variable has not been set."
+[ -z "$CUSTOM_ENV_AUTH_KEY" ] && error "AUTH_KEY secret CI/CD variable has not been set."
 
 AUTH_USER=$CUSTOM_ENV_AUTH_USER
 
@@ -50,7 +50,7 @@ exit 1
 
 AUTH_USER_WORK=$(runuser "$AUTH_USER" --login --command "echo \$WORK")
 
-: "${AUTH_USER_WORK:?"${TXT_RED}${TXT_BOLD}Could not determine $AUTH_USER's \$WORK directory.${TXT_CLEAR}"}"
+[ -z "$AUTH_USER_WORK" ] && error "Could not determine $AUTH_USER's \$WORK directory."
 
 BASE_DIR=$AUTH_USER_WORK/gitlab-runner/builds/${CUSTOM_ENV_CI_CONCURRENT_PROJECT_ID:?}/${CUSTOM_ENV_CI_PROJECT_NAMESPACE:?}/${CUSTOM_ENV_CI_PROJECT_NAME:?}
 
diff --git a/runner_scripts/root/config.sh b/runner_scripts/root/config.sh
index eef981390677e0f456299e84bea74590ed23031f..16d120a715f7d75c2eb81bed03f149e1d513e5c8 100755
--- a/runner_scripts/root/config.sh
+++ b/runner_scripts/root/config.sh
@@ -8,14 +8,14 @@ TXT_GREEN="\e[32m"
 TXT_CLEAR="\e[0m"
 TXT_BOLD="\e[1m"
 
-: "${CUSTOM_ENV_AUTH_USER:?"${TXT_RED}${TXT_BOLD}AUTH_USER CI/CD variable has not been set.${TXT_CLEAR}"}"
-: "${CUSTOM_ENV_AUTH_KEY:?"${TXT_RED}${TXT_BOLD}AUTH_KEY secret CI/CD variable has not been set.${TXT_CLEAR}"}"
+[ -z "$CUSTOM_ENV_AUTH_USER" ] && error "AUTH_USER CI/CD variable has not been set."
+[ -z "$CUSTOM_ENV_AUTH_KEY" ] && error "AUTH_KEY secret CI/CD variable has not been set."
 
 AUTH_USER=$CUSTOM_ENV_AUTH_USER
 
 AUTH_USER_WORK=$(runuser "$AUTH_USER" --login --command "echo \$WORK")
 
-: "${AUTH_USER_WORK:?"${TXT_RED}${TXT_BOLD}Could not determine $AUTH_USER's \$WORK directory.${TXT_CLEAR}"}"
+[ -z "$AUTH_USER_WORK" ] && error "Could not determine $AUTH_USER's \$WORK directory."
 
 cat << EOS
 {
diff --git a/runner_scripts/root/run.sh b/runner_scripts/root/run.sh
index a219b75bc6ea7ce8e052829ef7aec040f9e1bdf2..5cb26a5296ac85fdf3980f32a1ba59e2dc27c92d 100755
--- a/runner_scripts/root/run.sh
+++ b/runner_scripts/root/run.sh
@@ -30,8 +30,8 @@ function error {
 
 ## User authentication
 
-: "${CUSTOM_ENV_AUTH_USER:?"AUTH_USER CI/CD variable has not been set."}"
-: "${CUSTOM_ENV_AUTH_KEY:?"AUTH_KEY CI/CD variable has not been set."}"
+[ -z "$CUSTOM_ENV_AUTH_USER" ] && error "AUTH_USER CI/CD variable has not been set."
+[ -z "$CUSTOM_ENV_AUTH_KEY" ] && error "AUTH_KEY secret CI/CD variable has not been set."
 
 AUTH_USER=$CUSTOM_ENV_AUTH_USER
 
@@ -57,7 +57,7 @@ AUTH_USER_HOME=$(getent passwd "$AUTH_USER" | awk -F ":" '{print $6}')
 AUTH_USER_SHELL=$(getent passwd "$AUTH_USER" | awk -F ":" '{print $7}')
 AUTH_USER_WORK=$(runuser "$AUTH_USER" --login --command "echo \$WORK")
 
-: "${AUTH_USER_WORK:?"Could not determine $AUTH_USER's \$WORK directory."}"
+[ -z "$AUTH_USER_WORK" ] && error "Could not determine $AUTH_USER's \$WORK directory."
 
 chown -R "$AUTH_USER" "$TMPDIR"
 
@@ -79,7 +79,7 @@ if [[ ("$2" == "step_script" || "$2" == "build_script") && "${CUSTOM_ENV_NO_SLUR
     : "${SLURM_NODELIST:="phinally"}" # default node: phinally
 
     if [ ! $(sinfo -n "$SLURM_NODELIST" -h -O NodeList) ]; then
-        echo "${TXT_RED}${TXT_BOLD}Unknown node \"$SLURM_NODELIST\" specified. Available nodes: ${TXT_CLEAR}" >&2
+        echo -e "${TXT_RED}${TXT_BOLD}Unknown node \"$SLURM_NODELIST\" specified. Available nodes: ${TXT_CLEAR}" >&2
         echo "$(sinfo -N -o '%N %c %m')" >&2
         error "Exiting..."
     fi