diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 0cfcba5..ee9ee93 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -13,13 +13,17 @@ repos:
           - --ignore-regex=.*codespell-ignore$
           #- --write-changes  # Uncomment to write changes
         exclude_types: [csv, json]
-  - repo: https://github.com/adrienverge/yamllint
-    rev: v1.32.0
-    hooks:
-      - id: yamllint
-        ignore: .github/
   - repo: https://github.com/pre-commit/mirrors-prettier
     rev: v2.7.1
     hooks:
       - id: prettier
         args: ["--print-width", "100"]
+  - repo: https://github.com/adrienverge/yamllint
+    rev: v1.32.0
+    hooks:
+      - id: yamllint
+        ignore: .github/
+  - repo: https://github.com/shellcheck-py/shellcheck-py
+    rev: v0.10.0.1
+    hooks:
+      - id: shellcheck
diff --git a/check_container_upgrade b/check_container_upgrade
index 05100b1..83cab82 100755
--- a/check_container_upgrade
+++ b/check_container_upgrade
@@ -16,7 +16,7 @@ MAX_PARALLEL_CHECKS=4
 ONLY_CONTAINERS=()
 EXCLUDED_CONTAINERS=( buildx_buildkit_default )
 REBUILD=0
-REBUILD_DATA_DIR="/var/log/$(basename $0)"
+REBUILD_DATA_DIR="/var/log/$(basename "$0")"
 REBUILD_CRON=0
 DEPLOY_CRON=0
 declare -rA CHECK_PLUGINS=(
@@ -24,38 +24,43 @@ declare -rA CHECK_PLUGINS=(
     ["/usr/lib/nagios/plugins/check_apk"]="/usr/lib/nagios/plugins/check_apk"
 )
 
-function now() { [[ -z "$1" ]] && date "+%F %H:%M:%S" || date -d "@$1" "+%F %H:%M:%S" ; }
+function now() {
+    if [[ -z "$1" ]]; then date "+%F %H:%M:%S"; else date -d "@$1" "+%F %H:%M:%S"; fi
+}
 function current_time() { date "+%s"; }
 
 function debug() {
     [[ $DEBUG -eq 0 ]] && return
     if [[ -n "$LOG_FILE" ]] && [[ $CONSOLE -eq 1 ]]; then
-        echo -e "$(now) - [DEBUG] $@" | tee -a "$LOG_FILE" 2>&1
+        echo -e "$(now) - [DEBUG] $*" | tee -a "$LOG_FILE" 2>&1
     elif [[ -n "$LOG_FILE" ]]; then
-        echo -e "$(now) - [DEBUG] $@" >> "$LOG_FILE"
+        echo -e "$(now) - [DEBUG] $*" >> "$LOG_FILE"
     else
-        >&2 echo -e "[DEBUG] $@"
+        >&2 echo -e "[DEBUG] $*"
     fi
 }
 
 function log() {
-    [[ -n "$LOG_FILE" ]] && echo -e "$(now) - [$1] ${@:2}" >> "$LOG_FILE"
-    [[ "$1" == "ERROR" ]] && >&2 echo -e "ERROR - ${@:2}" || echo -e "${@:2}"
+    [[ -n "$LOG_FILE" ]] && echo -e "$(now) - [$1] ${*:2}" >> "$LOG_FILE"
+    if [[ "$1" == "ERROR" ]]; then
+        >&2 echo -e "ERROR - ${*:2}"
+    else
+        echo -e "${*:2}"
+    fi
 }
 
-function message() { log INFO $@ ; }
-function error() { log ERROR $@ ; }
+function message() { log INFO "$@" ; }
+function error() { log ERROR "$@" ; }
 
 function is_empty() {
-    [ $# -gt 0 ] && return 1
+    [[ $# -gt 0 ]] && return 1
     return 0
 }
 
 function in_array() {
-    param=$1;
+    local param=$1 elem;
     shift;
-    for elem in "$@";
-    do
+    for elem in "$@"; do
         [[ "$param" = "$elem" ]] && return 0;
     done;
     return 1
@@ -69,13 +74,13 @@ function implode() {
 }
 
 function format_duration {
-    local T=$1
-    local D=$((T/60/60/24))
-    local H=$((T/60/60%24))
-    local M=$((T/60%60))
-    local S=$((T%60))
-    (( $D > 0 )) && printf '%d days and ' $D
-    printf '%02d:%02d:%02d' $H $M $S
+    local t=$1
+    local d=$((t/60/60/24))
+    local h=$((t/60/60%24))
+    local m=$((t/60%60))
+    local s=$((t%60))
+    [[ $d -gt 0 ]] && printf '%d days and ' $d
+    printf '%02d:%02d:%02d' $h $m $s
 }
 
 REBUILD_STATUS_FILE=""
@@ -84,58 +89,64 @@ function rebuild_status_file() {
     [[ -z "$REBUILD_STATUS_FILE" ]] && \
         REBUILD_STATUS_FILE="$REBUILD_DATA_DIR/status.json"
     [[ -e "$REBUILD_STATUS_FILE" ]] || echo '{}' > "$REBUILD_STATUS_FILE"
-    echo "$REBUILD_STATUS_FILE"
 }
 
 function rebuild_status() {
-    if [[ -z "$1" ]]; then
-        cat "$(rebuild_status_file)"
+    local output_var=$1
+    [[ -n "$REBUILD_STATUS_FILE" ]] || rebuild_status_file
+    if [[ -z "$2" ]]; then
+        declare -g "$output_var=$( cat "$REBUILD_STATUS_FILE" )"
     else
-        rebuild_status | jq -r --arg container "$1" '.[$container]'
+        declare -g "$output_var=$(
+            jq -r --arg container "$2" '.[$container]' < "$REBUILD_STATUS_FILE"
+        )"
     fi
 }
 
 function update_rebuild_status() {
+    local data
     if [[ "$1" == "-d" ]]; then
-        local data=$(
-            rebuild_status | jq \
+        rebuild_status DATA
+        # shellcheck disable=SC2153
+        data=$(
+            jq \
                 --arg container "$2" \
-                'del(.[$container])'
+                'del(.[$container])' <<< "$DATA"
         )
     else
-        local args=( --arg container "$1" )
-        local expr=( )
+        local args=( --arg container "$1" ) arg name value exp=( )
         for arg in "${@:2}"; do
-            local name=$( echo "$arg" | cut -d'=' -f1 )
-            local value=$( echo "$arg" | sed 's/[^=]\+=//' )
+            name=$( head -n 1 <<< "$arg" | cut -d'=' -f1 )
+            # shellcheck disable=SC2001
+            value=$( sed "s/$name=//" <<< "$arg" )
             args+=( --arg "$name" "$value" )
-            expr+=( ".[\$container].$name=\$$name" )
+            exp+=( ".[\$container].${name}=\$${name}" )
         done
-        local data=$(
-            rebuild_status | jq \
-            "${args[@]}" "$( implode ' | ' "${expr[@]}" )"
+        rebuild_status DATA
+        data=$(
+            jq "${args[@]}" "$( implode ' | ' "${exp[@]}" )" <<< "$DATA"
         )
     fi
-    cat <<< $data > $(rebuild_status_file)
+    cat <<< "$data" > "$REBUILD_STATUS_FILE"
 }
 
 function remove_rebuild_status() {
-    rebuild_status_file > /dev/null
+    [[ -n "$REBUILD_STATUS_FILE" ]] || rebuild_status_file
     [[ -e "$REBUILD_STATUS_FILE" ]] || return 0
     debug "Remove previous rebuild status file ($REBUILD_STATUS_FILE) and log files it contains"
-    for log in $( jq -r '.[] | .log' $REBUILD_STATUS_FILE ); do
+    for log in $( jq -r '.[] | .log' "$REBUILD_STATUS_FILE" ); do
         debug "  remove old container log file $log"
-        rm -f $log
+        rm -f "$log"
     done
     debug "  remove status file"
     rm -f "$REBUILD_STATUS_FILE"
 }
 
 function usage() {
-    error="$1"
-    [ -n "$error" ] && message "$error"
+    local error="$1"
+    [[ -n "$error" ]] && message "$error"
     cat << EOF
-Usage : $(basename $0) [-d] [-E /path/to/engine] [container1,...]
+Usage : $(basename "$0") [-d] [-E /path/to/engine] [container1,...]
     -E [path]               Force a specific engine (possible values: ${POSSIBLE_ENGINES[@]},
                             default: $ENGINE)
     -x [container]          Exclude specified container (could be repeat)
@@ -156,13 +167,12 @@ Usage : $(basename $0) [-d] [-E /path/to/engine] [container1,...]
     -X                      Enable bash tracing (=set -x)
     -h                      Show this message
 EOF
-    [ -n "$error" ] && exit 1
+    [[ -n "$error" ]] && exit 1
     exit 0
 }
 
 idx=1
-while [ $idx -le $# ]
-do
+while [[ $idx -le $# ]]; do
         OPT=${!idx}
         case $OPT in
         -d)
@@ -181,9 +191,8 @@ do
         -E)
             ((idx++))
             ENGINE=${!idx}
-            if [ ! -x "$ENGINE" ]
-            then
-                in_array $ENGINE ${POSSIBLE_ENGINES[@]} || usage "Invalid engine $ENGINE"
+            if [[ ! -x "$ENGINE" ]]; then
+                in_array "$ENGINE" "${POSSIBLE_ENGINES[@]}" || usage "Invalid engine $ENGINE"
             fi
         ;;
         -f)
@@ -199,7 +208,7 @@ do
         ;;
         -x)
             ((idx++))
-            EXCLUDED_CONTAINERS+=( ${!idx} )
+            EXCLUDED_CONTAINERS+=( "${!idx}" )
         ;;
         -M)
             ((idx++))
@@ -215,33 +224,27 @@ do
             DEPLOY_CRON=1
         ;;
         *)
-            ONLY_CONTAINERS+=( $OPT )
+            ONLY_CONTAINERS+=( "$OPT" )
         ;;
         esac
         ((idx++))
 done
 
-debug "Start with parameters: $@"
+debug "Start with parameters: $*"
 
-! is_empty $ONLY_CONTAINERS && debug "Only containers: ${ONLY_CONTAINERS[@]}"
+is_empty "${ONLY_CONTAINERS[@]}" || debug "Only containers: ${ONLY_CONTAINERS[*]}"
 
-if [ "$ENGINE" == "auto" ]
-then
+if [[ "$ENGINE" == "auto" ]]; then
     debug "Auto-detect engine..."
-    for engine in ${POSSIBLE_ENGINES[@]}
-    do
-        [ "$engine" == "auto" ] && continue
-        which "$engine" > /dev/null 2>&1
-        if [ $? -ne 0 ]
-        then
-            debug "$engine not found"
-            continue
+    for engine in "${POSSIBLE_ENGINES[@]}"; do
+        [[ "$engine" == "auto" ]] && continue
+        if which "$engine" > /dev/null 2>&1; then
+            ENGINE="$engine"
+            break
         fi
-        ENGINE="$engine"
-        break
+        debug "$engine not found"
     done
-    if [ -z "$ENGINE" ]
-    then
+    if [[ -z "$ENGINE" ]]; then
         message "UNKNOWN - Fail to auto-detect engine"
         exit 3
     fi
@@ -260,29 +263,29 @@ if [[ -n "$DOCKERCOMPOSE_FILE" ]]; then
 fi
 
 if [[ $REBUILD_CRON -eq 1 ]]; then
-    to_rebuild=(
-        $(
-            rebuild_status | jq -r -c \
-                'to_entries[] | select((.value.start_date|not) and (.value.error|not)) | .key'
-        )
+    rebuild_status DATA
+    mapfile -t to_rebuild < <(
+         jq -r -c 'to_entries[] | select(
+            (.value.start_date|not) and (.value.error|not)
+        ) | .key' <<< "$DATA"
     )
     if [[ ${#to_rebuild[@]} -eq 0 ]]; then
         debug "No container need to be rebuild"
         exit 0
     fi
-    message "${#to_rebuild[@]} container(s) to rebuild: ${to_rebuild[@]}"
+    message "${#to_rebuild[@]} container(s) to rebuild: ${to_rebuild[*]}"
     error=0
-    for container in ${to_rebuild[@]}; do
+    for container in "${to_rebuild[@]}"; do
         log="$REBUILD_DATA_DIR/$container.log"
         message "  $container: start building image (log=$log)"
         start_time=$(current_time)
-        update_rebuild_status "$container" "start_date=$(now $start_time)" "log=$log"
-        $COMPOSE_BIN -f $DOCKERCOMPOSE_FILE build --no-cache $container >> $log 2>&1
+        update_rebuild_status "$container" "start_date=$(now "$start_time")" "log=$log"
+        "$COMPOSE_BIN" -f "$DOCKERCOMPOSE_FILE" build --no-cache "$container" >> "$log" 2>&1
         result=$?
         end_time=$(current_time)
         (( duration=end_time-start_time ))
-        duration=$(format_duration $duration)
-        container_info=( "end_date=$(now $end_time)" "duration=$duration" )
+        duration=$(format_duration "$duration")
+        container_info=( "end_date=$(now "$end_time")" "duration=$duration" )
         if [[ $result -eq 0 ]]; then
             message "  $container: rebuilt in $duration"
         else
@@ -296,26 +299,24 @@ if [[ $REBUILD_CRON -eq 1 ]]; then
 fi
 
 if [[ $DEPLOY_CRON -eq 1 ]]; then
-    to_deploy=(
-        $(
-            rebuild_status | jq -r -c \
-                'to_entries[] | select((.value.end_date) and (.value.error|not)) | .key'
-        )
+    rebuild_status DATA
+    mapfile -t to_deploy < <(
+        jq -r -c \
+            'to_entries[] | select((.value.end_date) and (.value.error|not)) | .key' <<< "$DATA"
     )
     if [[ ${#to_deploy[@]} -eq 0 ]]; then
         debug "No container need to be deploy"
         exit 0
     fi
-    message "${#to_deploy[@]} container(s) to deploy: ${to_deploy[@]}"
+    message "${#to_deploy[@]} container(s) to deploy: ${to_deploy[*]}"
     error=0
-    for container in ${to_deploy[@]}; do
+    for container in "${to_deploy[@]}"; do
         message "  $container: deploying..."
         log="$REBUILD_DATA_DIR/$container.log"
-        $COMPOSE_BIN -f $DOCKERCOMPOSE_FILE up -d --no-deps $container > $log 2>&1
-        if [[ $? -eq 0 ]]; then
+        if $COMPOSE_BIN -f "$DOCKERCOMPOSE_FILE" up -d --no-deps "$container" > "$log" 2>&1; then
             message "  $container: done"
             update_rebuild_status -d "$container"
-			rm -f $log
+            rm -f "$log"
         else
             error "  $container: fail to deploy new container image"
             update_rebuild_status "$container" "error=fail to deploy new container image"
@@ -331,113 +332,106 @@ declare -A CONTAINER_STATUS_FILE
 declare -A CONTAINER_PID
 declare -A UP_TO_DATE
 declare -A ERRORS
-declare -A UNKNOWNS
+declare -a UNKNOWNS
 declare -A UPGRADABLE_CONTAINERS
 CHECKED_CONTAINERS=( )
 
 debug "List running containers..."
-[[ -n "$DOCKERCOMPOSE_FILE" ]] && \
-    RUNNING_CONTAINERS=$($COMPOSE_BIN -f $DOCKERCOMPOSE_FILE ps --format '{{.Service}}' | tr '\n' ' ') ||
-    RUNNING_CONTAINERS=$($ENGINE ps --format '{{.Names}}' | tr '\n' ' ')
+if [[ -n "$DOCKERCOMPOSE_FILE" ]]; then
+    RUNNING_CONTAINERS=$(
+        $COMPOSE_BIN -f "$DOCKERCOMPOSE_FILE" ps --format '{{.Service}}' | tr '\n' ' '
+    )
+else
+    RUNNING_CONTAINERS=$( $ENGINE ps --format '{{.Names}}' | tr '\n' ' ' )
+fi
 debug "Running containers: $RUNNING_CONTAINERS"
 
 function exec_in_container() {
-    container=$1
+    local container=$1
     shift;
-    if [ -n "$DOCKERCOMPOSE_FILE" ]
-    then
-        $COMPOSE_BIN -f $DOCKERCOMPOSE_FILE exec $container $@
+    if [[ -n "$DOCKERCOMPOSE_FILE" ]]; then
+        $COMPOSE_BIN -f "$DOCKERCOMPOSE_FILE" exec "$container" "$@"
         return $?
     fi
-    $ENGINE exec $container $@
+    $ENGINE exec "$container" "$@"
     return $?
 }
 
 # Implement check inside a function to allow running it in parallel
 # Parameters : [container] [output file]
 function check_container() {
-    container="$1"
-    output_file="$2"
-    STATUS=""
-    for check_plugin in ${CHECK_PLUGINS[@]}
-    do
-        exec_in_container $container test -e $check_plugin > /dev/null 2>&1
-        if [ $? -ne 0 ]
-        then
+    local container="$1" output_file="$2" status="" check_plugin check_plugin_cmd=() status ex
+    for check_plugin in "${!CHECK_PLUGINS[@]}"; do
+        if ! exec_in_container "$container" test -e "$check_plugin" > /dev/null 2>&1; then
             debug "$container - Plugin $check_plugin not found"
             continue
         fi
         debug "$container - Plugin $check_plugin found, use it"
-        STATUS="$(exec_in_container $container ${CHECK_PLUGINS[${check_plugin}]} 2>&1)"
+        read -ra check_plugin_cmd <<< "${CHECK_PLUGINS[${check_plugin}]}"
+        status="$( exec_in_container "$container" "${check_plugin_cmd[@]}" 2>&1 )"
         ex=$?
-        debug "$container - Plugin output: $STATUS"
+        debug "$container - Plugin output: $status"
         debug "$container - Plugin exit code: $ex"
         break
     done
-    if [ -z "$STATUS" ]
-    then
+    if [[ -z "$status" ]]; then
         debug "$container - No check plugin found"
-        STATUS="UNKNOWN - No check plugin available"
+        status="UNKNOWN - No check plugin available"
         ex=3
     fi
-    echo $STATUS > $output_file
+    echo -e "$status" > "$output_file"
     return $ex
 }
 
 debug "Trigger check of all selected containers..."
-for container in $RUNNING_CONTAINERS
-do
-    if ! is_empty $ONLY_CONTAINERS && ! in_array $container ${ONLY_CONTAINERS[@]}
-    then
+for container in $RUNNING_CONTAINERS; do
+    if ! is_empty "${ONLY_CONTAINERS[@]}" && ! in_array "$container" "${ONLY_CONTAINERS[@]}"; then
         debug "$container - Ignored"
         continue
     fi
-    if in_array $container ${EXCLUDED_CONTAINERS[@]}
-    then
+    if in_array "$container" "${EXCLUDED_CONTAINERS[@]}"; then
         debug "$container - Excluded"
         continue
     fi
-    if [ $MAX_PARALLEL_CHECKS -gt 0 -a "$(jobs | wc -l)" -ge $MAX_PARALLEL_CHECKS ]
-    then
+    if [[ "$MAX_PARALLEL_CHECKS" -gt 0 ]] && \
+        [[ "$(jobs | wc -l)" -ge "$MAX_PARALLEL_CHECKS" ]]; then
         debug "Max parallel checks count reached. Waiting some check ending"
         wait -n
         debug "Some check ended, continue"
     fi
     CHECKED_CONTAINERS+=( "$container" )
     CONTAINER_STATUS_FILE+=( ["$container"]=$( mktemp ) )
-    check_container $container ${CONTAINER_STATUS_FILE[$container]} & CONTAINER_PID+=( ["$container"]=$! )
+    check_container "$container" "${CONTAINER_STATUS_FILE[$container]}" & CONTAINER_PID+=( ["$container"]=$! )
 done
 
 debug "Wait for each individual container check and handle their result..."
-for container in ${!CONTAINER_PID[@]}
-do
+for container in "${!CONTAINER_PID[@]}"; do
     pid=${CONTAINER_PID[$container]}
     debug "$container - Waiting for PID ${pid}..."
-    wait $pid
+    wait "$pid"
     ex=$?
     debug "$container - Check return ${ex}"
-    STATUS=$( cat ${CONTAINER_STATUS_FILE[$container]} )
-    rm -f ${CONTAINER_STATUS_FILE[$container]}
-    if [ $ex -eq 0 ]
-    then
+    STATUS=$( cat "${CONTAINER_STATUS_FILE[$container]}" )
+    rm -f "${CONTAINER_STATUS_FILE[$container]}"
+    if [[ $ex -eq 0 ]]; then
         UP_TO_DATE+=( ["$container"]=$STATUS )
     else
         ERRORS+=( ["$container"]=$STATUS )
-        [ $ex -ge 3 ] && UNKNOWNS+=( "$container" ) || \
+        if [[ $ex -ge 3 ]]; then
+            UNKNOWNS+=( "$container" )
+        else
             UPGRADABLE_CONTAINERS+=( ["$container"]="$STATUS" )
+        fi
     fi
-    [ $EXIT_CODE -ge $ex ] && continue
-    [ $ex -gt 3 ] && ex=3
+    [[ $EXIT_CODE -ge $ex ]] && continue
+    [[ $ex -gt 3 ]] && ex=3
     EXIT_CODE=$ex
 done
 
 NOTFOUNDS=()
-if ! is_empty $ONLY_CONTAINERS
-then
-    for container in ${ONLY_CONTAINERS[@]}
-    do
-        if ! in_array $container ${CHECKED_CONTAINERS[@]}
-        then
+if ! is_empty "${ONLY_CONTAINERS[@]}"; then
+    for container in "${ONLY_CONTAINERS[@]}"; do
+        if ! in_array "$container" "${CHECKED_CONTAINERS[@]}"; then
             debug "$container - Container not found"
             ERRORS+=( ["$container"]="Container not found" )
             NOTFOUNDS+=( "$container" )
@@ -455,7 +449,7 @@ debug "Containers with errors (${#ERRORS[@]}): $( implode ", " "${!ERRORS[@]}" )
 debug "Not found containers (${#NOTFOUNDS[@]}): $( implode ", " "${NOTFOUNDS[@]}" )"
 
 # Compute performance data
-let CONTAINER_COUNTS=${#CHECKED_CONTAINERS[@]}+${#NOTFOUNDS[@]}
+(( CONTAINER_COUNTS=${#CHECKED_CONTAINERS[@]}+${#NOTFOUNDS[@]} ))
 PERF_DATA=(
     "uptodate_containers=${#UP_TO_DATE[@]};;;0;$CONTAINER_COUNTS"
     "upgradable_containers=${#UPGRADABLE_CONTAINERS[@]};;;0;$CONTAINER_COUNTS"
@@ -483,31 +477,30 @@ case $EXIT_CODE in
 esac
 
 # Trigger container build (if need, enabled and docker compose file is provided)
-if [ $REBUILD -eq 1 ]
-then
-    debug "Check if we have to trigger some rebuild (status file: $(rebuild_status_file))"
-    if [ ${#UPGRADABLE_CONTAINERS[@]} -eq 0 ]
-    then
+if [[ $REBUILD -eq 1 ]]; then
+    [[ -n "$REBUILD_STATUS_FILE" ]] || rebuild_status_file
+    debug "Check if we have to trigger some rebuild (status file: $REBUILD_STATUS_FILE)"
+    if [ ${#UPGRADABLE_CONTAINERS[@]} -eq 0 ]; then
         debug "No upgradable container to rebuild"
         remove_rebuild_status
-    elif [ -z "$DOCKERCOMPOSE_FILE" ]
-    then
+    elif [[ -z "$DOCKERCOMPOSE_FILE" ]]; then
         message
         message "WARNING: No docker compose file provided, can't trigger rebuild of following" \
             "container(s):"
-        message "- $( implode "\n- " ${UPGRADABLE_CONTAINERS[@]} )"
+        message "- $( implode "\n- " "${UPGRADABLE_CONTAINERS[@]}" )"
     else
         message "Rebuilding containers:"
         REBUILT_CONTAINERS=()
-        for container in ${!UPGRADABLE_CONTAINERS[@]}; do
+        for container in "${!UPGRADABLE_CONTAINERS[@]}"; do
             need_rebuild=0
-            container_data=$( rebuild_status "$container" )
-            if [[ "$container_data" != "null" ]]; then
-                debug "$container: data=$container_data"
-                trigger_date=$( jq -r .trigger_date <<< $container_data )
-                start_date=$( jq -r .start_date <<< $container_data )
-                end_date=$( jq -r .end_date <<< $container_data )
-                log=$( jq -r .log <<< $container_data )
+            rebuild_status CONTAINER_DATA "$container"
+            # shellcheck disable=SC2153
+            if [[ "$CONTAINER_DATA" != "null" ]]; then
+                debug "$container: data='$CONTAINER_DATA'"
+                trigger_date=$( jq -r .trigger_date <<< "$CONTAINER_DATA" )
+                start_date=$( jq -r .start_date <<< "$CONTAINER_DATA" )
+                end_date=$( jq -r .end_date <<< "$CONTAINER_DATA" )
+                log=$( jq -r .log <<< "$CONTAINER_DATA" )
                 if [[ "$start_date" == "null" ]]; then
                     debug "$container: build triggered but not yet started"
                     message "- $container: rebuild triggered on $trigger_date and not yet started"
@@ -517,18 +510,18 @@ then
                     message "- $container: rebuild triggered on $trigger_date and started on" \
                         "$start_date, but not yet finish (log: $log)"
                 else
-                    duration=$( jq -r .duration <<< $container_data )
+                    duration=$( jq -r .duration <<< "$CONTAINER_DATA" )
                     debug "$container: rebuilt in $duration on $start_date (finish on $end_date)"
-                    prev_status=$( jq -r .status <<< $container_data )
+                    prev_status=$( jq -r .status <<< "$CONTAINER_DATA" )
                     if [[ "$prev_status" == "${UPGRADABLE_CONTAINERS[$container]}" ]]; then
-                        error=$( jq -r .error <<< $container_data )
+                        error=$( jq -r .error <<< "$CONTAINER_DATA" )
                         if [[ "$error" != "null" ]]; then
                             message "- $container: $error (log: $log)"
                         else
                             message "- $container: already rebuilt in $duration (rebuild" \
                                 "triggered on $trigger_date, started on $start_date and finish" \
-                                "at $end_date,log: $log)"
-                            REBUILT_CONTAINERS+=( $container )
+                                "at $end_date, log: $log)"
+                            REBUILT_CONTAINERS+=( "$container" )
                         fi
                     else
                         update_rebuild_status -d "$container"
@@ -556,21 +549,19 @@ then
             message "Some containers are ready to be recreated and restarted."
             message "Run the following command to do it:"
             message
-            message "  $COMPOSE_BIN -f $DOCKERCOMPOSE_FILE up -d --no-deps ${REBUILT_CONTAINERS[@]}"
+            message "  $COMPOSE_BIN -f $DOCKERCOMPOSE_FILE up -d --no-deps ${REBUILT_CONTAINERS[*]}"
         fi
         message
     fi
 fi
 
 # Display details, starting by errors
-for container in ${!ERRORS[@]}
-do
-    message ${container} - ${ERRORS[${container}]}
+for container in "${!ERRORS[@]}"; do
+    message "${container}" - "${ERRORS[${container}]}"
 done
 
-for container in ${!UP_TO_DATE[@]}
-do
-    message ${container} - ${UP_TO_DATE[${container}]}
+for container in "${!UP_TO_DATE[@]}"; do
+    message "${container}" - "${UP_TO_DATE[${container}]}"
 done
 
 exit $EXIT_CODE