diff --git a/entrypoint/10-listen-on-ipv6-by-default.sh b/entrypoint/10-listen-on-ipv6-by-default.sh
index 29898b1..f786c00 100755
--- a/entrypoint/10-listen-on-ipv6-by-default.sh
+++ b/entrypoint/10-listen-on-ipv6-by-default.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=4:ts=4:et
 
 set -e
@@ -9,59 +9,59 @@ entrypoint_log() {
     fi
 }
 
-ME=$(basename "$0")
+ME=$(basename "${0}")
 DEFAULT_CONF_FILE="etc/nginx/conf.d/default.conf"
 
 # check if we have ipv6 available
 if [ ! -f "/proc/net/if_inet6" ]; then
-    entrypoint_log "$ME: info: ipv6 not available"
+    entrypoint_log "${ME}: info: ipv6 not available"
     exit 0
 fi
 
-if [ ! -f "/$DEFAULT_CONF_FILE" ]; then
-    entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE is not a file or does not exist"
+if [ ! -f "/${DEFAULT_CONF_FILE}" ]; then
+    entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} is not a file or does not exist"
     exit 0
 fi
 
 # check if the file can be modified, e.g. not on a r/o filesystem
-touch /$DEFAULT_CONF_FILE 2>/dev/null || { entrypoint_log "$ME: info: can not modify /$DEFAULT_CONF_FILE (read-only file system?)"; exit 0; }
+touch /${DEFAULT_CONF_FILE} 2>/dev/null || { entrypoint_log "${ME}: info: can not modify /${DEFAULT_CONF_FILE} (read-only file system?)"; exit 0; }
 
 # check if the file is already modified, e.g. on a container restart
-grep -q "listen  \[::]\:8080;" /$DEFAULT_CONF_FILE && { entrypoint_log "$ME: info: IPv6 listen already enabled"; exit 0; }
+grep -q "listen  \[::]\:8080;" /${DEFAULT_CONF_FILE} && { entrypoint_log "${ME}: info: IPv6 listen already enabled"; exit 0; }
 
 if [ -f "/etc/os-release" ]; then
     . /etc/os-release
 else
-    entrypoint_log "$ME: info: can not guess the operating system"
+    entrypoint_log "${ME}: info: can not guess the operating system"
     exit 0
 fi
 
-entrypoint_log "$ME: info: Getting the checksum of /$DEFAULT_CONF_FILE"
+entrypoint_log "${ME}: info: Getting the checksum of /${DEFAULT_CONF_FILE}"
 
-case "$ID" in
+case "${ID}" in
     "debian")
-        CHECKSUM=$(dpkg-query --show --showformat='${Conffiles}\n' nginx | grep $DEFAULT_CONF_FILE | cut -d' ' -f 3)
-        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | md5sum -c - >/dev/null 2>&1 || {
-            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
+        CHECKSUM=$(dpkg-query --show --showformat='${Conffiles}\n' nginx | grep ${DEFAULT_CONF_FILE} | cut -d' ' -f 3)
+        echo "${CHECKSUM}  /${DEFAULT_CONF_FILE}" | md5sum -c - >/dev/null 2>&1 || {
+            entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} differs from the packaged version"
             exit 0
         }
         ;;
     "alpine")
-        CHECKSUM=$(apk manifest nginx 2>/dev/null| grep $DEFAULT_CONF_FILE | cut -d' ' -f 1 | cut -d ':' -f 2)
-        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | sha1sum -c - >/dev/null 2>&1 || {
-            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
+        CHECKSUM=$(apk manifest nginx 2>/dev/null| grep ${DEFAULT_CONF_FILE} | cut -d' ' -f 1 | cut -d ':' -f 2)
+        echo "${CHECKSUM}  /${DEFAULT_CONF_FILE}" | sha1sum -c - >/dev/null 2>&1 || {
+            entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} differs from the packaged version"
             exit 0
         }
         ;;
     *)
-        entrypoint_log "$ME: info: Unsupported distribution"
+        entrypoint_log "${ME}: info: Unsupported distribution"
         exit 0
         ;;
 esac
 
 # enable ipv6 on default.conf listen sockets
-sed -i -E 's,listen       8080;,listen       8080;\n    listen  [::]:8080;,' /$DEFAULT_CONF_FILE
+sed -i -E 's,listen       8080;,listen       8080;\n    listen  [::]:8080;,' /${DEFAULT_CONF_FILE}
 
-entrypoint_log "$ME: info: Enabled listen on IPv6 in /$DEFAULT_CONF_FILE"
+entrypoint_log "${ME}: info: Enabled listen on IPv6 in /${DEFAULT_CONF_FILE}"
 
 exit 0
diff --git a/entrypoint/15-local-resolvers.envsh b/entrypoint/15-local-resolvers.envsh
index e830dda..87d88ea 100755
--- a/entrypoint/15-local-resolvers.envsh
+++ b/entrypoint/15-local-resolvers.envsh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=2:ts=2:sts=2:et
 
 set -eu
diff --git a/entrypoint/20-envsubst-on-templates.sh b/entrypoint/20-envsubst-on-templates.sh
index 6938405..febbc7e 100755
--- a/entrypoint/20-envsubst-on-templates.sh
+++ b/entrypoint/20-envsubst-on-templates.sh
@@ -1,8 +1,8 @@
-#!/bin/sh
+#!/usr/bin/env sh
 
 set -e
 
-ME=$(basename "$0")
+ME=$(basename "${0}")
 
 entrypoint_log() {
   if [ -z "${NGINX_ENTRYPOINT_QUIET_LOGS:-}" ]; then
@@ -13,16 +13,16 @@ entrypoint_log() {
 add_stream_block() {
   local conffile="/etc/nginx/nginx.conf"
 
-  if grep -q -E "\s*stream\s*\{" "$conffile"; then
-    entrypoint_log "$ME: $conffile contains a stream block; include $stream_output_dir/*.conf to enable stream templates"
+  if grep -q -E "\s*stream\s*\{" "${conffile}"; then
+    entrypoint_log "${ME}: ${conffile} contains a stream block; include ${stream_output_dir}/*.conf to enable stream templates"
   else
     # check if the file can be modified, e.g. not on a r/o filesystem
-    touch "$conffile" 2>/dev/null || { entrypoint_log "$ME: info: can not modify $conffile (read-only file system?)"; exit 0; }
-    entrypoint_log "$ME: Appending stream block to $conffile to include $stream_output_dir/*.conf"
-    cat << END >> "$conffile"
-# added by "$ME" on "$(date)"
+    touch "${conffile}" 2>/dev/null || { entrypoint_log "${ME}: info: can not modify ${conffile} (read-only file system?)"; exit 0; }
+    entrypoint_log "${ME}: Appending stream block to ${conffile} to include ${stream_output_dir}/*.conf"
+    cat << END >> "${conffile}"
+# added by "${ME}" on "$(date)"
 stream {
-  include $stream_output_dir/*.conf;
+  include ${stream_output_dir}/*.conf;
 }
 END
   fi
@@ -38,37 +38,37 @@ auto_envsubst() {
 
   local template defined_envs relative_path output_path subdir
   defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
-  [ -d "$template_dir" ] || return 0
-  if [ ! -w "$output_dir" ]; then
-    entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"
+  [ -d "${template_dir}" ] || return 0
+  if [ ! -w "${output_dir}" ]; then
+    entrypoint_log "${ME}: ERROR: ${template_dir} exists, but ${output_dir} is not writable"
     return 0
   fi
-  find "$template_dir" -follow -type f -name "*$suffix" -print | while read -r template; do
-    relative_path="${template#"$template_dir/"}"
-    output_path="$output_dir/${relative_path%"$suffix"}"
-    subdir=$(dirname "$relative_path")
+  find "${template_dir}" -follow -type f -name "*${suffix}" -print | while read -r template; do
+    relative_path="${template#"${template_dir}/"}"
+    output_path="${output_dir}/${relative_path%"${suffix}"}"
+    subdir=$(dirname "${relative_path}")
     # create a subdirectory where the template file exists
-    mkdir -p "$output_dir/$subdir"
-    entrypoint_log "$ME: Running envsubst on $template to $output_path"
-    envsubst "$defined_envs" < "$template" > "$output_path"
+    mkdir -p "${output_dir}/${subdir}"
+    entrypoint_log "${ME}: Running envsubst on ${template} to ${output_path}"
+    envsubst "${defined_envs}" < "${template}" > "${output_path}"
   done
 
   # Print the first file with the stream suffix, this will be false if there are none
-  if test -n "$(find "$template_dir" -name "*$stream_suffix" -print -quit)"; then
-    mkdir -p "$stream_output_dir"
-    if [ ! -w "$stream_output_dir" ]; then
-      entrypoint_log "$ME: ERROR: $template_dir exists, but $stream_output_dir is not writable"
+  if test -n "$(find "${template_dir}" -name "*${stream_suffix}" -print -quit)"; then
+    mkdir -p "${stream_output_dir}"
+    if [ ! -w "${stream_output_dir}" ]; then
+      entrypoint_log "${ME}: ERROR: ${template_dir} exists, but ${stream_output_dir} is not writable"
       return 0
     fi
     add_stream_block
-    find "$template_dir" -follow -type f -name "*$stream_suffix" -print | while read -r template; do
-      relative_path="${template#"$template_dir/"}"
-      output_path="$stream_output_dir/${relative_path%"$stream_suffix"}"
-      subdir=$(dirname "$relative_path")
+    find "${template_dir}" -follow -type f -name "*${stream_suffix}" -print | while read -r template; do
+      relative_path="${template#"${template_dir}/"}"
+      output_path="${stream_output_dir}/${relative_path%"${stream_suffix}"}"
+      subdir=$(dirname "${relative_path}")
       # create a subdirectory where the template file exists
-      mkdir -p "$stream_output_dir/$subdir"
-      entrypoint_log "$ME: Running envsubst on $template to $output_path"
-      envsubst "$defined_envs" < "$template" > "$output_path"
+      mkdir -p "${stream_output_dir}/${subdir}"
+      entrypoint_log "${ME}: Running envsubst on ${template} to ${output_path}"
+      envsubst "${defined_envs}" < "${template}" > "${output_path}"
     done
   fi
 }
diff --git a/entrypoint/30-tune-worker-processes.sh b/entrypoint/30-tune-worker-processes.sh
index defb994..df3885a 100755
--- a/entrypoint/30-tune-worker-processes.sh
+++ b/entrypoint/30-tune-worker-processes.sh
@@ -1,31 +1,31 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=2:ts=2:sts=2:et
 
 set -eu
 
 LC_ALL=C
-ME=$(basename "$0")
+ME=$(basename "${0}")
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 
 [ "${NGINX_ENTRYPOINT_WORKER_PROCESSES_AUTOTUNE:-}" ] || exit 0
 
-touch /etc/nginx/nginx.conf 2>/dev/null || { echo >&2 "$ME: error: can not modify /etc/nginx/nginx.conf (read-only file system?)"; exit 0; }
+touch /etc/nginx/nginx.conf 2>/dev/null || { echo >&2 "\${ME}: error: can not modify /etc/nginx/nginx.conf (read-only file system?)"; exit 0; }
 
 ceildiv() {
-  num=$1
-  div=$2
+  num=${1}
+  div=${2}
   echo $(( (num + div - 1) / div ))
 }
 
 get_cpuset() {
-  cpusetroot=$1
-  cpusetfile=$2
+  cpusetroot=${1}
+  cpusetfile=${2}
   ncpu=0
-  [ -f "$cpusetroot/$cpusetfile" ] || return 1
-  for token in $( tr ',' ' ' < "$cpusetroot/$cpusetfile" ); do
-    case "$token" in
+  [ -f "${cpusetroot}/${cpusetfile}" ] || return 1
+  for token in $( tr ',' ' ' < "${cpusetroot}/${cpusetfile}" ); do
+    case "${token}" in
       *-*)
-        count=$( seq $(echo "$token" | tr '-' ' ') | wc -l )
+        count=$( seq $(echo "${token}" | tr '-' ' ') | wc -l )
         ncpu=$(( ncpu+count ))
         ;;
       *)
@@ -33,38 +33,38 @@ get_cpuset() {
         ;;
     esac
   done
-  echo "$ncpu"
+  echo "${ncpu}"
 }
 
 get_quota() {
-  cpuroot=$1
+  cpuroot=${1}
   ncpu=0
-  [ -f "$cpuroot/cpu.cfs_quota_us" ] || return 1
-  [ -f "$cpuroot/cpu.cfs_period_us" ] || return 1
-  cfs_quota=$( cat "$cpuroot/cpu.cfs_quota_us" )
-  cfs_period=$( cat "$cpuroot/cpu.cfs_period_us" )
-  [ "$cfs_quota" = "-1" ] && return 1
-  [ "$cfs_period" = "0" ] && return 1
-  ncpu=$( ceildiv "$cfs_quota" "$cfs_period" )
-  [ "$ncpu" -gt 0 ] || return 1
-  echo "$ncpu"
+  [ -f "${cpuroot}/cpu.cfs_quota_us" ] || return 1
+  [ -f "${cpuroot}/cpu.cfs_period_us" ] || return 1
+  cfs_quota=$( cat "${cpuroot}/cpu.cfs_quota_us" )
+  cfs_period=$( cat "${cpuroot}/cpu.cfs_period_us" )
+  [ "${cfs_quota}" = "-1" ] && return 1
+  [ "${cfs_period}" = "0" ] && return 1
+  ncpu=$( ceildiv "${cfs_quota}" "${cfs_period}" )
+  [ "${ncpu}" -gt 0 ] || return 1
+  echo "${ncpu}"
 }
 
 get_quota_v2() {
-  cpuroot=$1
+  cpuroot=${1}
   ncpu=0
-  [ -f "$cpuroot/cpu.max" ] || return 1
-  cfs_quota=$( cut -d' ' -f 1 < "$cpuroot/cpu.max" )
-  cfs_period=$( cut -d' ' -f 2 < "$cpuroot/cpu.max" )
-  [ "$cfs_quota" = "max" ] && return 1
-  [ "$cfs_period" = "0" ] && return 1
-  ncpu=$( ceildiv "$cfs_quota" "$cfs_period" )
-  [ "$ncpu" -gt 0 ] || return 1
-  echo "$ncpu"
+  [ -f "${cpuroot}/cpu.max" ] || return 1
+  cfs_quota=$( cut -d' ' -f 1 < "${cpuroot}/cpu.max" )
+  cfs_period=$( cut -d' ' -f 2 < "${cpuroot}/cpu.max" )
+  [ "${cfs_quota}" = "max" ] && return 1
+  [ "${cfs_period}" = "0" ] && return 1
+  ncpu=$( ceildiv "${cfs_quota}" "${cfs_period}" )
+  [ "${ncpu}" -gt 0 ] || return 1
+  echo "${ncpu}"
 }
 
 get_cgroup_v1_path() {
-  needle=$1
+  needle=${1}
   found=
   foundroot=
   mountpoint=
@@ -73,21 +73,21 @@ get_cgroup_v1_path() {
   [ -r "/proc/self/cgroup" ] || return 1
 
   while IFS= read -r line; do
-    case "$needle" in
+    case "${needle}" in
       "cpuset")
-        case "$line" in
+        case "${line}" in
           *cpuset*)
-            found=$( echo "$line" | cut -d ' ' -f 4,5 )
+            found=$( echo "${line}" | cut -d ' ' -f 4,5 )
             break
             ;;
         esac
         ;;
       "cpu")
-        case "$line" in
+        case "${line}" in
           *cpuset*)
             ;;
           *cpu,cpuacct*|*cpuacct,cpu|*cpuacct*|*cpu*)
-            found=$( echo "$line" | cut -d ' ' -f 4,5 )
+            found=$( echo "${line}" | cut -d ' ' -f 4,5 )
             break
             ;;
         esac
@@ -97,20 +97,20 @@ $( grep -F -- '- cgroup ' /proc/self/mountinfo )
 __EOF__
 
   while IFS= read -r line; do
-    controller=$( echo "$line" | cut -d: -f 2 )
-    case "$needle" in
+    controller=$( echo "${line}" | cut -d: -f 2 )
+    case "${needle}" in
       "cpuset")
-        case "$controller" in
+        case "${controller}" in
           cpuset)
-            mountpoint=$( echo "$line" | cut -d: -f 3 )
+            mountpoint=$( echo "${line}" | cut -d: -f 3 )
             break
             ;;
         esac
         ;;
       "cpu")
-        case "$controller" in
+        case "${controller}" in
           cpu,cpuacct|cpuacct,cpu|cpuacct|cpu)
-            mountpoint=$( echo "$line" | cut -d: -f 3 )
+            mountpoint=$( echo "${line}" | cut -d: -f 3 )
             break
             ;;
         esac
@@ -122,13 +122,13 @@ __EOF__
 
   case "${found%% *}" in
     "/")
-      foundroot="${found##* }$mountpoint"
+      foundroot="${found##* }${mountpoint}"
       ;;
-    "$mountpoint")
+    "${mountpoint}")
       foundroot="${found##* }"
       ;;
   esac
-  echo "$foundroot"
+  echo "${foundroot}"
 }
 
 get_cgroup_v2_path() {
@@ -140,13 +140,13 @@ get_cgroup_v2_path() {
   [ -r "/proc/self/cgroup" ] || return 1
 
   while IFS= read -r line; do
-    found=$( echo "$line" | cut -d ' ' -f 4,5 )
+    found=$( echo "${line}" | cut -d ' ' -f 4,5 )
   done << __EOF__
 $( grep -F -- '- cgroup2 ' /proc/self/mountinfo )
 __EOF__
 
   while IFS= read -r line; do
-    mountpoint=$( echo "$line" | cut -d: -f 3 )
+    mountpoint=$( echo "${line}" | cut -d: -f 3 )
 done << __EOF__
 $( grep -F -- '0::' /proc/self/cgroup )
 __EOF__
@@ -156,13 +156,13 @@ __EOF__
       return 1
       ;;
     "/")
-      foundroot="${found##* }$mountpoint"
+      foundroot="${found##* }${mountpoint}"
       ;;
-    "$mountpoint" | /../*)
+    "${mountpoint}" | /../*)
       foundroot="${found##* }"
       ;;
   esac
-  echo "$foundroot"
+  echo "${foundroot}"
 }
 
 ncpu_online=$( getconf _NPROCESSORS_ONLN )
@@ -171,18 +171,18 @@ ncpu_quota=
 ncpu_cpuset_v2=
 ncpu_quota_v2=
 
-cpuset=$( get_cgroup_v1_path "cpuset" ) && ncpu_cpuset=$( get_cpuset "$cpuset" "cpuset.effective_cpus" ) || ncpu_cpuset=$ncpu_online
-cpu=$( get_cgroup_v1_path "cpu" ) && ncpu_quota=$( get_quota "$cpu" ) || ncpu_quota=$ncpu_online
-cgroup_v2=$( get_cgroup_v2_path ) && ncpu_cpuset_v2=$( get_cpuset "$cgroup_v2" "cpuset.cpus.effective" ) || ncpu_cpuset_v2=$ncpu_online
-cgroup_v2=$( get_cgroup_v2_path ) && ncpu_quota_v2=$( get_quota_v2 "$cgroup_v2" ) || ncpu_quota_v2=$ncpu_online
+cpuset=$( get_cgroup_v1_path "cpuset" ) && ncpu_cpuset=$( get_cpuset "${cpuset}" "cpuset.effective_cpus" ) || ncpu_cpuset=${ncpu_online}
+cpu=$( get_cgroup_v1_path "cpu" ) && ncpu_quota=$( get_quota "${cpu}" ) || ncpu_quota=${ncpu_online}
+cgroup_v2=$( get_cgroup_v2_path ) && ncpu_cpuset_v2=$( get_cpuset "${cgroup_v2}" "cpuset.cpus.effective" ) || ncpu_cpuset_v2=${ncpu_online}
+cgroup_v2=$( get_cgroup_v2_path ) && ncpu_quota_v2=$( get_quota_v2 "${cgroup_v2}" ) || ncpu_quota_v2=${ncpu_online}
 
 ncpu=$( printf "%s\n%s\n%s\n%s\n%s\n" \
-               "$ncpu_online" \
-               "$ncpu_cpuset" \
-               "$ncpu_quota" \
-               "$ncpu_cpuset_v2" \
-               "$ncpu_quota_v2" \
+               "${ncpu_online}" \
+               "${ncpu_cpuset}" \
+               "${ncpu_quota}" \
+               "${ncpu_cpuset_v2}" \
+               "${ncpu_quota_v2}" \
                | sort -n \
                | head -n 1 )
 
-sed -i.bak -r 's/^(worker_processes)(.*)$/# Commented out by '"$ME"' on '"$(date)"'\n#\1\2\n\1 '"$ncpu"';/' /etc/nginx/nginx.conf
+sed -i.bak -r 's/^(worker_processes)(.*)$/# Commented out by '"${ME}"' on '"$(date)"'\n#\1\2\n\1 '"${ncpu}"';/' /etc/nginx/nginx.conf
diff --git a/entrypoint/docker-entrypoint.sh b/entrypoint/docker-entrypoint.sh
index 8ea04f2..cac74ec 100755
--- a/entrypoint/docker-entrypoint.sh
+++ b/entrypoint/docker-entrypoint.sh
@@ -1,47 +1,47 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=4:ts=4:et
 
 set -e
 
 entrypoint_log() {
     if [ -z "${NGINX_ENTRYPOINT_QUIET_LOGS:-}" ]; then
-        echo "$@"
+        echo "${@}"
     fi
 }
 
-if [ "$1" = "nginx" ] || [ "$1" = "nginx-debug" ]; then
+if [ "${1}" = "nginx" ] || [ "${1}" = "nginx-debug" ]; then
     if /usr/bin/find "/docker-entrypoint.d/" -mindepth 1 -maxdepth 1 -type f -print -quit 2>/dev/null | read v; then
-        entrypoint_log "$0: /docker-entrypoint.d/ is not empty, will attempt to perform configuration"
+        entrypoint_log "${0}: /docker-entrypoint.d/ is not empty, will attempt to perform configuration"
 
-        entrypoint_log "$0: Looking for shell scripts in /docker-entrypoint.d/"
+        entrypoint_log "${0}: Looking for shell scripts in /docker-entrypoint.d/"
         find "/docker-entrypoint.d/" -follow -type f -print | sort -V | while read -r f; do
-            case "$f" in
+            case "${f}" in
                 *.envsh)
-                    if [ -x "$f" ]; then
-                        entrypoint_log "$0: Sourcing $f";
-                        . "$f"
+                    if [ -r "${f}" ]; then
+                        entrypoint_log "${0}: Sourcing ${f}";
+                        . "${f}"
                     else
-                        # warn on shell scripts without exec bit
-                        entrypoint_log "$0: Ignoring $f, not executable";
+                        # warn on shell scripts not readable
+                        entrypoint_log "${0}: Ignoring ${f}, not readable";
                     fi
                     ;;
                 *.sh)
-                    if [ -x "$f" ]; then
-                        entrypoint_log "$0: Launching $f";
-                        "$f"
+                    if [ -x "${f}" ]; then
+                        entrypoint_log "${0}: Launching ${f}";
+                        "${f}"
                     else
                         # warn on shell scripts without exec bit
-                        entrypoint_log "$0: Ignoring $f, not executable";
+                        entrypoint_log "${0}: Ignoring ${f}, not executable";
                     fi
                     ;;
-                *) entrypoint_log "$0: Ignoring $f";;
+                *) entrypoint_log "${0}: Ignoring ${f}";;
             esac
         done
 
-        entrypoint_log "$0: Configuration complete; ready for start up"
+        entrypoint_log "${0}: Configuration complete; ready for start up"
     else
-        entrypoint_log "$0: No files found in /docker-entrypoint.d/, skipping configuration"
+        entrypoint_log "${0}: No files found in /docker-entrypoint.d/, skipping configuration"
     fi
 fi
 
-exec "$@"
+exec "${@}"
diff --git a/mainline/alpine-slim/10-listen-on-ipv6-by-default.sh b/mainline/alpine-slim/10-listen-on-ipv6-by-default.sh
index 29898b1..f786c00 100755
--- a/mainline/alpine-slim/10-listen-on-ipv6-by-default.sh
+++ b/mainline/alpine-slim/10-listen-on-ipv6-by-default.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=4:ts=4:et
 
 set -e
@@ -9,59 +9,59 @@ entrypoint_log() {
     fi
 }
 
-ME=$(basename "$0")
+ME=$(basename "${0}")
 DEFAULT_CONF_FILE="etc/nginx/conf.d/default.conf"
 
 # check if we have ipv6 available
 if [ ! -f "/proc/net/if_inet6" ]; then
-    entrypoint_log "$ME: info: ipv6 not available"
+    entrypoint_log "${ME}: info: ipv6 not available"
     exit 0
 fi
 
-if [ ! -f "/$DEFAULT_CONF_FILE" ]; then
-    entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE is not a file or does not exist"
+if [ ! -f "/${DEFAULT_CONF_FILE}" ]; then
+    entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} is not a file or does not exist"
     exit 0
 fi
 
 # check if the file can be modified, e.g. not on a r/o filesystem
-touch /$DEFAULT_CONF_FILE 2>/dev/null || { entrypoint_log "$ME: info: can not modify /$DEFAULT_CONF_FILE (read-only file system?)"; exit 0; }
+touch /${DEFAULT_CONF_FILE} 2>/dev/null || { entrypoint_log "${ME}: info: can not modify /${DEFAULT_CONF_FILE} (read-only file system?)"; exit 0; }
 
 # check if the file is already modified, e.g. on a container restart
-grep -q "listen  \[::]\:8080;" /$DEFAULT_CONF_FILE && { entrypoint_log "$ME: info: IPv6 listen already enabled"; exit 0; }
+grep -q "listen  \[::]\:8080;" /${DEFAULT_CONF_FILE} && { entrypoint_log "${ME}: info: IPv6 listen already enabled"; exit 0; }
 
 if [ -f "/etc/os-release" ]; then
     . /etc/os-release
 else
-    entrypoint_log "$ME: info: can not guess the operating system"
+    entrypoint_log "${ME}: info: can not guess the operating system"
     exit 0
 fi
 
-entrypoint_log "$ME: info: Getting the checksum of /$DEFAULT_CONF_FILE"
+entrypoint_log "${ME}: info: Getting the checksum of /${DEFAULT_CONF_FILE}"
 
-case "$ID" in
+case "${ID}" in
     "debian")
-        CHECKSUM=$(dpkg-query --show --showformat='${Conffiles}\n' nginx | grep $DEFAULT_CONF_FILE | cut -d' ' -f 3)
-        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | md5sum -c - >/dev/null 2>&1 || {
-            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
+        CHECKSUM=$(dpkg-query --show --showformat='${Conffiles}\n' nginx | grep ${DEFAULT_CONF_FILE} | cut -d' ' -f 3)
+        echo "${CHECKSUM}  /${DEFAULT_CONF_FILE}" | md5sum -c - >/dev/null 2>&1 || {
+            entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} differs from the packaged version"
             exit 0
         }
         ;;
     "alpine")
-        CHECKSUM=$(apk manifest nginx 2>/dev/null| grep $DEFAULT_CONF_FILE | cut -d' ' -f 1 | cut -d ':' -f 2)
-        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | sha1sum -c - >/dev/null 2>&1 || {
-            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
+        CHECKSUM=$(apk manifest nginx 2>/dev/null| grep ${DEFAULT_CONF_FILE} | cut -d' ' -f 1 | cut -d ':' -f 2)
+        echo "${CHECKSUM}  /${DEFAULT_CONF_FILE}" | sha1sum -c - >/dev/null 2>&1 || {
+            entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} differs from the packaged version"
             exit 0
         }
         ;;
     *)
-        entrypoint_log "$ME: info: Unsupported distribution"
+        entrypoint_log "${ME}: info: Unsupported distribution"
         exit 0
         ;;
 esac
 
 # enable ipv6 on default.conf listen sockets
-sed -i -E 's,listen       8080;,listen       8080;\n    listen  [::]:8080;,' /$DEFAULT_CONF_FILE
+sed -i -E 's,listen       8080;,listen       8080;\n    listen  [::]:8080;,' /${DEFAULT_CONF_FILE}
 
-entrypoint_log "$ME: info: Enabled listen on IPv6 in /$DEFAULT_CONF_FILE"
+entrypoint_log "${ME}: info: Enabled listen on IPv6 in /${DEFAULT_CONF_FILE}"
 
 exit 0
diff --git a/mainline/alpine-slim/15-local-resolvers.envsh b/mainline/alpine-slim/15-local-resolvers.envsh
index e830dda..87d88ea 100755
--- a/mainline/alpine-slim/15-local-resolvers.envsh
+++ b/mainline/alpine-slim/15-local-resolvers.envsh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=2:ts=2:sts=2:et
 
 set -eu
diff --git a/mainline/alpine-slim/20-envsubst-on-templates.sh b/mainline/alpine-slim/20-envsubst-on-templates.sh
index 6938405..febbc7e 100755
--- a/mainline/alpine-slim/20-envsubst-on-templates.sh
+++ b/mainline/alpine-slim/20-envsubst-on-templates.sh
@@ -1,8 +1,8 @@
-#!/bin/sh
+#!/usr/bin/env sh
 
 set -e
 
-ME=$(basename "$0")
+ME=$(basename "${0}")
 
 entrypoint_log() {
   if [ -z "${NGINX_ENTRYPOINT_QUIET_LOGS:-}" ]; then
@@ -13,16 +13,16 @@ entrypoint_log() {
 add_stream_block() {
   local conffile="/etc/nginx/nginx.conf"
 
-  if grep -q -E "\s*stream\s*\{" "$conffile"; then
-    entrypoint_log "$ME: $conffile contains a stream block; include $stream_output_dir/*.conf to enable stream templates"
+  if grep -q -E "\s*stream\s*\{" "${conffile}"; then
+    entrypoint_log "${ME}: ${conffile} contains a stream block; include ${stream_output_dir}/*.conf to enable stream templates"
   else
     # check if the file can be modified, e.g. not on a r/o filesystem
-    touch "$conffile" 2>/dev/null || { entrypoint_log "$ME: info: can not modify $conffile (read-only file system?)"; exit 0; }
-    entrypoint_log "$ME: Appending stream block to $conffile to include $stream_output_dir/*.conf"
-    cat << END >> "$conffile"
-# added by "$ME" on "$(date)"
+    touch "${conffile}" 2>/dev/null || { entrypoint_log "${ME}: info: can not modify ${conffile} (read-only file system?)"; exit 0; }
+    entrypoint_log "${ME}: Appending stream block to ${conffile} to include ${stream_output_dir}/*.conf"
+    cat << END >> "${conffile}"
+# added by "${ME}" on "$(date)"
 stream {
-  include $stream_output_dir/*.conf;
+  include ${stream_output_dir}/*.conf;
 }
 END
   fi
@@ -38,37 +38,37 @@ auto_envsubst() {
 
   local template defined_envs relative_path output_path subdir
   defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
-  [ -d "$template_dir" ] || return 0
-  if [ ! -w "$output_dir" ]; then
-    entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"
+  [ -d "${template_dir}" ] || return 0
+  if [ ! -w "${output_dir}" ]; then
+    entrypoint_log "${ME}: ERROR: ${template_dir} exists, but ${output_dir} is not writable"
     return 0
   fi
-  find "$template_dir" -follow -type f -name "*$suffix" -print | while read -r template; do
-    relative_path="${template#"$template_dir/"}"
-    output_path="$output_dir/${relative_path%"$suffix"}"
-    subdir=$(dirname "$relative_path")
+  find "${template_dir}" -follow -type f -name "*${suffix}" -print | while read -r template; do
+    relative_path="${template#"${template_dir}/"}"
+    output_path="${output_dir}/${relative_path%"${suffix}"}"
+    subdir=$(dirname "${relative_path}")
     # create a subdirectory where the template file exists
-    mkdir -p "$output_dir/$subdir"
-    entrypoint_log "$ME: Running envsubst on $template to $output_path"
-    envsubst "$defined_envs" < "$template" > "$output_path"
+    mkdir -p "${output_dir}/${subdir}"
+    entrypoint_log "${ME}: Running envsubst on ${template} to ${output_path}"
+    envsubst "${defined_envs}" < "${template}" > "${output_path}"
   done
 
   # Print the first file with the stream suffix, this will be false if there are none
-  if test -n "$(find "$template_dir" -name "*$stream_suffix" -print -quit)"; then
-    mkdir -p "$stream_output_dir"
-    if [ ! -w "$stream_output_dir" ]; then
-      entrypoint_log "$ME: ERROR: $template_dir exists, but $stream_output_dir is not writable"
+  if test -n "$(find "${template_dir}" -name "*${stream_suffix}" -print -quit)"; then
+    mkdir -p "${stream_output_dir}"
+    if [ ! -w "${stream_output_dir}" ]; then
+      entrypoint_log "${ME}: ERROR: ${template_dir} exists, but ${stream_output_dir} is not writable"
       return 0
     fi
     add_stream_block
-    find "$template_dir" -follow -type f -name "*$stream_suffix" -print | while read -r template; do
-      relative_path="${template#"$template_dir/"}"
-      output_path="$stream_output_dir/${relative_path%"$stream_suffix"}"
-      subdir=$(dirname "$relative_path")
+    find "${template_dir}" -follow -type f -name "*${stream_suffix}" -print | while read -r template; do
+      relative_path="${template#"${template_dir}/"}"
+      output_path="${stream_output_dir}/${relative_path%"${stream_suffix}"}"
+      subdir=$(dirname "${relative_path}")
       # create a subdirectory where the template file exists
-      mkdir -p "$stream_output_dir/$subdir"
-      entrypoint_log "$ME: Running envsubst on $template to $output_path"
-      envsubst "$defined_envs" < "$template" > "$output_path"
+      mkdir -p "${stream_output_dir}/${subdir}"
+      entrypoint_log "${ME}: Running envsubst on ${template} to ${output_path}"
+      envsubst "${defined_envs}" < "${template}" > "${output_path}"
     done
   fi
 }
diff --git a/mainline/alpine-slim/30-tune-worker-processes.sh b/mainline/alpine-slim/30-tune-worker-processes.sh
index defb994..df3885a 100755
--- a/mainline/alpine-slim/30-tune-worker-processes.sh
+++ b/mainline/alpine-slim/30-tune-worker-processes.sh
@@ -1,31 +1,31 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=2:ts=2:sts=2:et
 
 set -eu
 
 LC_ALL=C
-ME=$(basename "$0")
+ME=$(basename "${0}")
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 
 [ "${NGINX_ENTRYPOINT_WORKER_PROCESSES_AUTOTUNE:-}" ] || exit 0
 
-touch /etc/nginx/nginx.conf 2>/dev/null || { echo >&2 "$ME: error: can not modify /etc/nginx/nginx.conf (read-only file system?)"; exit 0; }
+touch /etc/nginx/nginx.conf 2>/dev/null || { echo >&2 "\${ME}: error: can not modify /etc/nginx/nginx.conf (read-only file system?)"; exit 0; }
 
 ceildiv() {
-  num=$1
-  div=$2
+  num=${1}
+  div=${2}
   echo $(( (num + div - 1) / div ))
 }
 
 get_cpuset() {
-  cpusetroot=$1
-  cpusetfile=$2
+  cpusetroot=${1}
+  cpusetfile=${2}
   ncpu=0
-  [ -f "$cpusetroot/$cpusetfile" ] || return 1
-  for token in $( tr ',' ' ' < "$cpusetroot/$cpusetfile" ); do
-    case "$token" in
+  [ -f "${cpusetroot}/${cpusetfile}" ] || return 1
+  for token in $( tr ',' ' ' < "${cpusetroot}/${cpusetfile}" ); do
+    case "${token}" in
       *-*)
-        count=$( seq $(echo "$token" | tr '-' ' ') | wc -l )
+        count=$( seq $(echo "${token}" | tr '-' ' ') | wc -l )
         ncpu=$(( ncpu+count ))
         ;;
       *)
@@ -33,38 +33,38 @@ get_cpuset() {
         ;;
     esac
   done
-  echo "$ncpu"
+  echo "${ncpu}"
 }
 
 get_quota() {
-  cpuroot=$1
+  cpuroot=${1}
   ncpu=0
-  [ -f "$cpuroot/cpu.cfs_quota_us" ] || return 1
-  [ -f "$cpuroot/cpu.cfs_period_us" ] || return 1
-  cfs_quota=$( cat "$cpuroot/cpu.cfs_quota_us" )
-  cfs_period=$( cat "$cpuroot/cpu.cfs_period_us" )
-  [ "$cfs_quota" = "-1" ] && return 1
-  [ "$cfs_period" = "0" ] && return 1
-  ncpu=$( ceildiv "$cfs_quota" "$cfs_period" )
-  [ "$ncpu" -gt 0 ] || return 1
-  echo "$ncpu"
+  [ -f "${cpuroot}/cpu.cfs_quota_us" ] || return 1
+  [ -f "${cpuroot}/cpu.cfs_period_us" ] || return 1
+  cfs_quota=$( cat "${cpuroot}/cpu.cfs_quota_us" )
+  cfs_period=$( cat "${cpuroot}/cpu.cfs_period_us" )
+  [ "${cfs_quota}" = "-1" ] && return 1
+  [ "${cfs_period}" = "0" ] && return 1
+  ncpu=$( ceildiv "${cfs_quota}" "${cfs_period}" )
+  [ "${ncpu}" -gt 0 ] || return 1
+  echo "${ncpu}"
 }
 
 get_quota_v2() {
-  cpuroot=$1
+  cpuroot=${1}
   ncpu=0
-  [ -f "$cpuroot/cpu.max" ] || return 1
-  cfs_quota=$( cut -d' ' -f 1 < "$cpuroot/cpu.max" )
-  cfs_period=$( cut -d' ' -f 2 < "$cpuroot/cpu.max" )
-  [ "$cfs_quota" = "max" ] && return 1
-  [ "$cfs_period" = "0" ] && return 1
-  ncpu=$( ceildiv "$cfs_quota" "$cfs_period" )
-  [ "$ncpu" -gt 0 ] || return 1
-  echo "$ncpu"
+  [ -f "${cpuroot}/cpu.max" ] || return 1
+  cfs_quota=$( cut -d' ' -f 1 < "${cpuroot}/cpu.max" )
+  cfs_period=$( cut -d' ' -f 2 < "${cpuroot}/cpu.max" )
+  [ "${cfs_quota}" = "max" ] && return 1
+  [ "${cfs_period}" = "0" ] && return 1
+  ncpu=$( ceildiv "${cfs_quota}" "${cfs_period}" )
+  [ "${ncpu}" -gt 0 ] || return 1
+  echo "${ncpu}"
 }
 
 get_cgroup_v1_path() {
-  needle=$1
+  needle=${1}
   found=
   foundroot=
   mountpoint=
@@ -73,21 +73,21 @@ get_cgroup_v1_path() {
   [ -r "/proc/self/cgroup" ] || return 1
 
   while IFS= read -r line; do
-    case "$needle" in
+    case "${needle}" in
       "cpuset")
-        case "$line" in
+        case "${line}" in
           *cpuset*)
-            found=$( echo "$line" | cut -d ' ' -f 4,5 )
+            found=$( echo "${line}" | cut -d ' ' -f 4,5 )
             break
             ;;
         esac
         ;;
       "cpu")
-        case "$line" in
+        case "${line}" in
           *cpuset*)
             ;;
           *cpu,cpuacct*|*cpuacct,cpu|*cpuacct*|*cpu*)
-            found=$( echo "$line" | cut -d ' ' -f 4,5 )
+            found=$( echo "${line}" | cut -d ' ' -f 4,5 )
             break
             ;;
         esac
@@ -97,20 +97,20 @@ $( grep -F -- '- cgroup ' /proc/self/mountinfo )
 __EOF__
 
   while IFS= read -r line; do
-    controller=$( echo "$line" | cut -d: -f 2 )
-    case "$needle" in
+    controller=$( echo "${line}" | cut -d: -f 2 )
+    case "${needle}" in
       "cpuset")
-        case "$controller" in
+        case "${controller}" in
           cpuset)
-            mountpoint=$( echo "$line" | cut -d: -f 3 )
+            mountpoint=$( echo "${line}" | cut -d: -f 3 )
             break
             ;;
         esac
         ;;
       "cpu")
-        case "$controller" in
+        case "${controller}" in
           cpu,cpuacct|cpuacct,cpu|cpuacct|cpu)
-            mountpoint=$( echo "$line" | cut -d: -f 3 )
+            mountpoint=$( echo "${line}" | cut -d: -f 3 )
             break
             ;;
         esac
@@ -122,13 +122,13 @@ __EOF__
 
   case "${found%% *}" in
     "/")
-      foundroot="${found##* }$mountpoint"
+      foundroot="${found##* }${mountpoint}"
       ;;
-    "$mountpoint")
+    "${mountpoint}")
       foundroot="${found##* }"
       ;;
   esac
-  echo "$foundroot"
+  echo "${foundroot}"
 }
 
 get_cgroup_v2_path() {
@@ -140,13 +140,13 @@ get_cgroup_v2_path() {
   [ -r "/proc/self/cgroup" ] || return 1
 
   while IFS= read -r line; do
-    found=$( echo "$line" | cut -d ' ' -f 4,5 )
+    found=$( echo "${line}" | cut -d ' ' -f 4,5 )
   done << __EOF__
 $( grep -F -- '- cgroup2 ' /proc/self/mountinfo )
 __EOF__
 
   while IFS= read -r line; do
-    mountpoint=$( echo "$line" | cut -d: -f 3 )
+    mountpoint=$( echo "${line}" | cut -d: -f 3 )
 done << __EOF__
 $( grep -F -- '0::' /proc/self/cgroup )
 __EOF__
@@ -156,13 +156,13 @@ __EOF__
       return 1
       ;;
     "/")
-      foundroot="${found##* }$mountpoint"
+      foundroot="${found##* }${mountpoint}"
       ;;
-    "$mountpoint" | /../*)
+    "${mountpoint}" | /../*)
       foundroot="${found##* }"
       ;;
   esac
-  echo "$foundroot"
+  echo "${foundroot}"
 }
 
 ncpu_online=$( getconf _NPROCESSORS_ONLN )
@@ -171,18 +171,18 @@ ncpu_quota=
 ncpu_cpuset_v2=
 ncpu_quota_v2=
 
-cpuset=$( get_cgroup_v1_path "cpuset" ) && ncpu_cpuset=$( get_cpuset "$cpuset" "cpuset.effective_cpus" ) || ncpu_cpuset=$ncpu_online
-cpu=$( get_cgroup_v1_path "cpu" ) && ncpu_quota=$( get_quota "$cpu" ) || ncpu_quota=$ncpu_online
-cgroup_v2=$( get_cgroup_v2_path ) && ncpu_cpuset_v2=$( get_cpuset "$cgroup_v2" "cpuset.cpus.effective" ) || ncpu_cpuset_v2=$ncpu_online
-cgroup_v2=$( get_cgroup_v2_path ) && ncpu_quota_v2=$( get_quota_v2 "$cgroup_v2" ) || ncpu_quota_v2=$ncpu_online
+cpuset=$( get_cgroup_v1_path "cpuset" ) && ncpu_cpuset=$( get_cpuset "${cpuset}" "cpuset.effective_cpus" ) || ncpu_cpuset=${ncpu_online}
+cpu=$( get_cgroup_v1_path "cpu" ) && ncpu_quota=$( get_quota "${cpu}" ) || ncpu_quota=${ncpu_online}
+cgroup_v2=$( get_cgroup_v2_path ) && ncpu_cpuset_v2=$( get_cpuset "${cgroup_v2}" "cpuset.cpus.effective" ) || ncpu_cpuset_v2=${ncpu_online}
+cgroup_v2=$( get_cgroup_v2_path ) && ncpu_quota_v2=$( get_quota_v2 "${cgroup_v2}" ) || ncpu_quota_v2=${ncpu_online}
 
 ncpu=$( printf "%s\n%s\n%s\n%s\n%s\n" \
-               "$ncpu_online" \
-               "$ncpu_cpuset" \
-               "$ncpu_quota" \
-               "$ncpu_cpuset_v2" \
-               "$ncpu_quota_v2" \
+               "${ncpu_online}" \
+               "${ncpu_cpuset}" \
+               "${ncpu_quota}" \
+               "${ncpu_cpuset_v2}" \
+               "${ncpu_quota_v2}" \
                | sort -n \
                | head -n 1 )
 
-sed -i.bak -r 's/^(worker_processes)(.*)$/# Commented out by '"$ME"' on '"$(date)"'\n#\1\2\n\1 '"$ncpu"';/' /etc/nginx/nginx.conf
+sed -i.bak -r 's/^(worker_processes)(.*)$/# Commented out by '"${ME}"' on '"$(date)"'\n#\1\2\n\1 '"${ncpu}"';/' /etc/nginx/nginx.conf
diff --git a/mainline/alpine-slim/docker-entrypoint.sh b/mainline/alpine-slim/docker-entrypoint.sh
index 8ea04f2..cac74ec 100755
--- a/mainline/alpine-slim/docker-entrypoint.sh
+++ b/mainline/alpine-slim/docker-entrypoint.sh
@@ -1,47 +1,47 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=4:ts=4:et
 
 set -e
 
 entrypoint_log() {
     if [ -z "${NGINX_ENTRYPOINT_QUIET_LOGS:-}" ]; then
-        echo "$@"
+        echo "${@}"
     fi
 }
 
-if [ "$1" = "nginx" ] || [ "$1" = "nginx-debug" ]; then
+if [ "${1}" = "nginx" ] || [ "${1}" = "nginx-debug" ]; then
     if /usr/bin/find "/docker-entrypoint.d/" -mindepth 1 -maxdepth 1 -type f -print -quit 2>/dev/null | read v; then
-        entrypoint_log "$0: /docker-entrypoint.d/ is not empty, will attempt to perform configuration"
+        entrypoint_log "${0}: /docker-entrypoint.d/ is not empty, will attempt to perform configuration"
 
-        entrypoint_log "$0: Looking for shell scripts in /docker-entrypoint.d/"
+        entrypoint_log "${0}: Looking for shell scripts in /docker-entrypoint.d/"
         find "/docker-entrypoint.d/" -follow -type f -print | sort -V | while read -r f; do
-            case "$f" in
+            case "${f}" in
                 *.envsh)
-                    if [ -x "$f" ]; then
-                        entrypoint_log "$0: Sourcing $f";
-                        . "$f"
+                    if [ -r "${f}" ]; then
+                        entrypoint_log "${0}: Sourcing ${f}";
+                        . "${f}"
                     else
-                        # warn on shell scripts without exec bit
-                        entrypoint_log "$0: Ignoring $f, not executable";
+                        # warn on shell scripts not readable
+                        entrypoint_log "${0}: Ignoring ${f}, not readable";
                     fi
                     ;;
                 *.sh)
-                    if [ -x "$f" ]; then
-                        entrypoint_log "$0: Launching $f";
-                        "$f"
+                    if [ -x "${f}" ]; then
+                        entrypoint_log "${0}: Launching ${f}";
+                        "${f}"
                     else
                         # warn on shell scripts without exec bit
-                        entrypoint_log "$0: Ignoring $f, not executable";
+                        entrypoint_log "${0}: Ignoring ${f}, not executable";
                     fi
                     ;;
-                *) entrypoint_log "$0: Ignoring $f";;
+                *) entrypoint_log "${0}: Ignoring ${f}";;
             esac
         done
 
-        entrypoint_log "$0: Configuration complete; ready for start up"
+        entrypoint_log "${0}: Configuration complete; ready for start up"
     else
-        entrypoint_log "$0: No files found in /docker-entrypoint.d/, skipping configuration"
+        entrypoint_log "${0}: No files found in /docker-entrypoint.d/, skipping configuration"
     fi
 fi
 
-exec "$@"
+exec "${@}"
diff --git a/mainline/debian/10-listen-on-ipv6-by-default.sh b/mainline/debian/10-listen-on-ipv6-by-default.sh
index 29898b1..f786c00 100755
--- a/mainline/debian/10-listen-on-ipv6-by-default.sh
+++ b/mainline/debian/10-listen-on-ipv6-by-default.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=4:ts=4:et
 
 set -e
@@ -9,59 +9,59 @@ entrypoint_log() {
     fi
 }
 
-ME=$(basename "$0")
+ME=$(basename "${0}")
 DEFAULT_CONF_FILE="etc/nginx/conf.d/default.conf"
 
 # check if we have ipv6 available
 if [ ! -f "/proc/net/if_inet6" ]; then
-    entrypoint_log "$ME: info: ipv6 not available"
+    entrypoint_log "${ME}: info: ipv6 not available"
     exit 0
 fi
 
-if [ ! -f "/$DEFAULT_CONF_FILE" ]; then
-    entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE is not a file or does not exist"
+if [ ! -f "/${DEFAULT_CONF_FILE}" ]; then
+    entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} is not a file or does not exist"
     exit 0
 fi
 
 # check if the file can be modified, e.g. not on a r/o filesystem
-touch /$DEFAULT_CONF_FILE 2>/dev/null || { entrypoint_log "$ME: info: can not modify /$DEFAULT_CONF_FILE (read-only file system?)"; exit 0; }
+touch /${DEFAULT_CONF_FILE} 2>/dev/null || { entrypoint_log "${ME}: info: can not modify /${DEFAULT_CONF_FILE} (read-only file system?)"; exit 0; }
 
 # check if the file is already modified, e.g. on a container restart
-grep -q "listen  \[::]\:8080;" /$DEFAULT_CONF_FILE && { entrypoint_log "$ME: info: IPv6 listen already enabled"; exit 0; }
+grep -q "listen  \[::]\:8080;" /${DEFAULT_CONF_FILE} && { entrypoint_log "${ME}: info: IPv6 listen already enabled"; exit 0; }
 
 if [ -f "/etc/os-release" ]; then
     . /etc/os-release
 else
-    entrypoint_log "$ME: info: can not guess the operating system"
+    entrypoint_log "${ME}: info: can not guess the operating system"
     exit 0
 fi
 
-entrypoint_log "$ME: info: Getting the checksum of /$DEFAULT_CONF_FILE"
+entrypoint_log "${ME}: info: Getting the checksum of /${DEFAULT_CONF_FILE}"
 
-case "$ID" in
+case "${ID}" in
     "debian")
-        CHECKSUM=$(dpkg-query --show --showformat='${Conffiles}\n' nginx | grep $DEFAULT_CONF_FILE | cut -d' ' -f 3)
-        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | md5sum -c - >/dev/null 2>&1 || {
-            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
+        CHECKSUM=$(dpkg-query --show --showformat='${Conffiles}\n' nginx | grep ${DEFAULT_CONF_FILE} | cut -d' ' -f 3)
+        echo "${CHECKSUM}  /${DEFAULT_CONF_FILE}" | md5sum -c - >/dev/null 2>&1 || {
+            entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} differs from the packaged version"
             exit 0
         }
         ;;
     "alpine")
-        CHECKSUM=$(apk manifest nginx 2>/dev/null| grep $DEFAULT_CONF_FILE | cut -d' ' -f 1 | cut -d ':' -f 2)
-        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | sha1sum -c - >/dev/null 2>&1 || {
-            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
+        CHECKSUM=$(apk manifest nginx 2>/dev/null| grep ${DEFAULT_CONF_FILE} | cut -d' ' -f 1 | cut -d ':' -f 2)
+        echo "${CHECKSUM}  /${DEFAULT_CONF_FILE}" | sha1sum -c - >/dev/null 2>&1 || {
+            entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} differs from the packaged version"
             exit 0
         }
         ;;
     *)
-        entrypoint_log "$ME: info: Unsupported distribution"
+        entrypoint_log "${ME}: info: Unsupported distribution"
         exit 0
         ;;
 esac
 
 # enable ipv6 on default.conf listen sockets
-sed -i -E 's,listen       8080;,listen       8080;\n    listen  [::]:8080;,' /$DEFAULT_CONF_FILE
+sed -i -E 's,listen       8080;,listen       8080;\n    listen  [::]:8080;,' /${DEFAULT_CONF_FILE}
 
-entrypoint_log "$ME: info: Enabled listen on IPv6 in /$DEFAULT_CONF_FILE"
+entrypoint_log "${ME}: info: Enabled listen on IPv6 in /${DEFAULT_CONF_FILE}"
 
 exit 0
diff --git a/mainline/debian/15-local-resolvers.envsh b/mainline/debian/15-local-resolvers.envsh
index e830dda..87d88ea 100755
--- a/mainline/debian/15-local-resolvers.envsh
+++ b/mainline/debian/15-local-resolvers.envsh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=2:ts=2:sts=2:et
 
 set -eu
diff --git a/mainline/debian/20-envsubst-on-templates.sh b/mainline/debian/20-envsubst-on-templates.sh
index 6938405..febbc7e 100755
--- a/mainline/debian/20-envsubst-on-templates.sh
+++ b/mainline/debian/20-envsubst-on-templates.sh
@@ -1,8 +1,8 @@
-#!/bin/sh
+#!/usr/bin/env sh
 
 set -e
 
-ME=$(basename "$0")
+ME=$(basename "${0}")
 
 entrypoint_log() {
   if [ -z "${NGINX_ENTRYPOINT_QUIET_LOGS:-}" ]; then
@@ -13,16 +13,16 @@ entrypoint_log() {
 add_stream_block() {
   local conffile="/etc/nginx/nginx.conf"
 
-  if grep -q -E "\s*stream\s*\{" "$conffile"; then
-    entrypoint_log "$ME: $conffile contains a stream block; include $stream_output_dir/*.conf to enable stream templates"
+  if grep -q -E "\s*stream\s*\{" "${conffile}"; then
+    entrypoint_log "${ME}: ${conffile} contains a stream block; include ${stream_output_dir}/*.conf to enable stream templates"
   else
     # check if the file can be modified, e.g. not on a r/o filesystem
-    touch "$conffile" 2>/dev/null || { entrypoint_log "$ME: info: can not modify $conffile (read-only file system?)"; exit 0; }
-    entrypoint_log "$ME: Appending stream block to $conffile to include $stream_output_dir/*.conf"
-    cat << END >> "$conffile"
-# added by "$ME" on "$(date)"
+    touch "${conffile}" 2>/dev/null || { entrypoint_log "${ME}: info: can not modify ${conffile} (read-only file system?)"; exit 0; }
+    entrypoint_log "${ME}: Appending stream block to ${conffile} to include ${stream_output_dir}/*.conf"
+    cat << END >> "${conffile}"
+# added by "${ME}" on "$(date)"
 stream {
-  include $stream_output_dir/*.conf;
+  include ${stream_output_dir}/*.conf;
 }
 END
   fi
@@ -38,37 +38,37 @@ auto_envsubst() {
 
   local template defined_envs relative_path output_path subdir
   defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
-  [ -d "$template_dir" ] || return 0
-  if [ ! -w "$output_dir" ]; then
-    entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"
+  [ -d "${template_dir}" ] || return 0
+  if [ ! -w "${output_dir}" ]; then
+    entrypoint_log "${ME}: ERROR: ${template_dir} exists, but ${output_dir} is not writable"
     return 0
   fi
-  find "$template_dir" -follow -type f -name "*$suffix" -print | while read -r template; do
-    relative_path="${template#"$template_dir/"}"
-    output_path="$output_dir/${relative_path%"$suffix"}"
-    subdir=$(dirname "$relative_path")
+  find "${template_dir}" -follow -type f -name "*${suffix}" -print | while read -r template; do
+    relative_path="${template#"${template_dir}/"}"
+    output_path="${output_dir}/${relative_path%"${suffix}"}"
+    subdir=$(dirname "${relative_path}")
     # create a subdirectory where the template file exists
-    mkdir -p "$output_dir/$subdir"
-    entrypoint_log "$ME: Running envsubst on $template to $output_path"
-    envsubst "$defined_envs" < "$template" > "$output_path"
+    mkdir -p "${output_dir}/${subdir}"
+    entrypoint_log "${ME}: Running envsubst on ${template} to ${output_path}"
+    envsubst "${defined_envs}" < "${template}" > "${output_path}"
   done
 
   # Print the first file with the stream suffix, this will be false if there are none
-  if test -n "$(find "$template_dir" -name "*$stream_suffix" -print -quit)"; then
-    mkdir -p "$stream_output_dir"
-    if [ ! -w "$stream_output_dir" ]; then
-      entrypoint_log "$ME: ERROR: $template_dir exists, but $stream_output_dir is not writable"
+  if test -n "$(find "${template_dir}" -name "*${stream_suffix}" -print -quit)"; then
+    mkdir -p "${stream_output_dir}"
+    if [ ! -w "${stream_output_dir}" ]; then
+      entrypoint_log "${ME}: ERROR: ${template_dir} exists, but ${stream_output_dir} is not writable"
       return 0
     fi
     add_stream_block
-    find "$template_dir" -follow -type f -name "*$stream_suffix" -print | while read -r template; do
-      relative_path="${template#"$template_dir/"}"
-      output_path="$stream_output_dir/${relative_path%"$stream_suffix"}"
-      subdir=$(dirname "$relative_path")
+    find "${template_dir}" -follow -type f -name "*${stream_suffix}" -print | while read -r template; do
+      relative_path="${template#"${template_dir}/"}"
+      output_path="${stream_output_dir}/${relative_path%"${stream_suffix}"}"
+      subdir=$(dirname "${relative_path}")
       # create a subdirectory where the template file exists
-      mkdir -p "$stream_output_dir/$subdir"
-      entrypoint_log "$ME: Running envsubst on $template to $output_path"
-      envsubst "$defined_envs" < "$template" > "$output_path"
+      mkdir -p "${stream_output_dir}/${subdir}"
+      entrypoint_log "${ME}: Running envsubst on ${template} to ${output_path}"
+      envsubst "${defined_envs}" < "${template}" > "${output_path}"
     done
   fi
 }
diff --git a/mainline/debian/30-tune-worker-processes.sh b/mainline/debian/30-tune-worker-processes.sh
index defb994..df3885a 100755
--- a/mainline/debian/30-tune-worker-processes.sh
+++ b/mainline/debian/30-tune-worker-processes.sh
@@ -1,31 +1,31 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=2:ts=2:sts=2:et
 
 set -eu
 
 LC_ALL=C
-ME=$(basename "$0")
+ME=$(basename "${0}")
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 
 [ "${NGINX_ENTRYPOINT_WORKER_PROCESSES_AUTOTUNE:-}" ] || exit 0
 
-touch /etc/nginx/nginx.conf 2>/dev/null || { echo >&2 "$ME: error: can not modify /etc/nginx/nginx.conf (read-only file system?)"; exit 0; }
+touch /etc/nginx/nginx.conf 2>/dev/null || { echo >&2 "\${ME}: error: can not modify /etc/nginx/nginx.conf (read-only file system?)"; exit 0; }
 
 ceildiv() {
-  num=$1
-  div=$2
+  num=${1}
+  div=${2}
   echo $(( (num + div - 1) / div ))
 }
 
 get_cpuset() {
-  cpusetroot=$1
-  cpusetfile=$2
+  cpusetroot=${1}
+  cpusetfile=${2}
   ncpu=0
-  [ -f "$cpusetroot/$cpusetfile" ] || return 1
-  for token in $( tr ',' ' ' < "$cpusetroot/$cpusetfile" ); do
-    case "$token" in
+  [ -f "${cpusetroot}/${cpusetfile}" ] || return 1
+  for token in $( tr ',' ' ' < "${cpusetroot}/${cpusetfile}" ); do
+    case "${token}" in
       *-*)
-        count=$( seq $(echo "$token" | tr '-' ' ') | wc -l )
+        count=$( seq $(echo "${token}" | tr '-' ' ') | wc -l )
         ncpu=$(( ncpu+count ))
         ;;
       *)
@@ -33,38 +33,38 @@ get_cpuset() {
         ;;
     esac
   done
-  echo "$ncpu"
+  echo "${ncpu}"
 }
 
 get_quota() {
-  cpuroot=$1
+  cpuroot=${1}
   ncpu=0
-  [ -f "$cpuroot/cpu.cfs_quota_us" ] || return 1
-  [ -f "$cpuroot/cpu.cfs_period_us" ] || return 1
-  cfs_quota=$( cat "$cpuroot/cpu.cfs_quota_us" )
-  cfs_period=$( cat "$cpuroot/cpu.cfs_period_us" )
-  [ "$cfs_quota" = "-1" ] && return 1
-  [ "$cfs_period" = "0" ] && return 1
-  ncpu=$( ceildiv "$cfs_quota" "$cfs_period" )
-  [ "$ncpu" -gt 0 ] || return 1
-  echo "$ncpu"
+  [ -f "${cpuroot}/cpu.cfs_quota_us" ] || return 1
+  [ -f "${cpuroot}/cpu.cfs_period_us" ] || return 1
+  cfs_quota=$( cat "${cpuroot}/cpu.cfs_quota_us" )
+  cfs_period=$( cat "${cpuroot}/cpu.cfs_period_us" )
+  [ "${cfs_quota}" = "-1" ] && return 1
+  [ "${cfs_period}" = "0" ] && return 1
+  ncpu=$( ceildiv "${cfs_quota}" "${cfs_period}" )
+  [ "${ncpu}" -gt 0 ] || return 1
+  echo "${ncpu}"
 }
 
 get_quota_v2() {
-  cpuroot=$1
+  cpuroot=${1}
   ncpu=0
-  [ -f "$cpuroot/cpu.max" ] || return 1
-  cfs_quota=$( cut -d' ' -f 1 < "$cpuroot/cpu.max" )
-  cfs_period=$( cut -d' ' -f 2 < "$cpuroot/cpu.max" )
-  [ "$cfs_quota" = "max" ] && return 1
-  [ "$cfs_period" = "0" ] && return 1
-  ncpu=$( ceildiv "$cfs_quota" "$cfs_period" )
-  [ "$ncpu" -gt 0 ] || return 1
-  echo "$ncpu"
+  [ -f "${cpuroot}/cpu.max" ] || return 1
+  cfs_quota=$( cut -d' ' -f 1 < "${cpuroot}/cpu.max" )
+  cfs_period=$( cut -d' ' -f 2 < "${cpuroot}/cpu.max" )
+  [ "${cfs_quota}" = "max" ] && return 1
+  [ "${cfs_period}" = "0" ] && return 1
+  ncpu=$( ceildiv "${cfs_quota}" "${cfs_period}" )
+  [ "${ncpu}" -gt 0 ] || return 1
+  echo "${ncpu}"
 }
 
 get_cgroup_v1_path() {
-  needle=$1
+  needle=${1}
   found=
   foundroot=
   mountpoint=
@@ -73,21 +73,21 @@ get_cgroup_v1_path() {
   [ -r "/proc/self/cgroup" ] || return 1
 
   while IFS= read -r line; do
-    case "$needle" in
+    case "${needle}" in
       "cpuset")
-        case "$line" in
+        case "${line}" in
           *cpuset*)
-            found=$( echo "$line" | cut -d ' ' -f 4,5 )
+            found=$( echo "${line}" | cut -d ' ' -f 4,5 )
             break
             ;;
         esac
         ;;
       "cpu")
-        case "$line" in
+        case "${line}" in
           *cpuset*)
             ;;
           *cpu,cpuacct*|*cpuacct,cpu|*cpuacct*|*cpu*)
-            found=$( echo "$line" | cut -d ' ' -f 4,5 )
+            found=$( echo "${line}" | cut -d ' ' -f 4,5 )
             break
             ;;
         esac
@@ -97,20 +97,20 @@ $( grep -F -- '- cgroup ' /proc/self/mountinfo )
 __EOF__
 
   while IFS= read -r line; do
-    controller=$( echo "$line" | cut -d: -f 2 )
-    case "$needle" in
+    controller=$( echo "${line}" | cut -d: -f 2 )
+    case "${needle}" in
       "cpuset")
-        case "$controller" in
+        case "${controller}" in
           cpuset)
-            mountpoint=$( echo "$line" | cut -d: -f 3 )
+            mountpoint=$( echo "${line}" | cut -d: -f 3 )
             break
             ;;
         esac
         ;;
       "cpu")
-        case "$controller" in
+        case "${controller}" in
           cpu,cpuacct|cpuacct,cpu|cpuacct|cpu)
-            mountpoint=$( echo "$line" | cut -d: -f 3 )
+            mountpoint=$( echo "${line}" | cut -d: -f 3 )
             break
             ;;
         esac
@@ -122,13 +122,13 @@ __EOF__
 
   case "${found%% *}" in
     "/")
-      foundroot="${found##* }$mountpoint"
+      foundroot="${found##* }${mountpoint}"
       ;;
-    "$mountpoint")
+    "${mountpoint}")
       foundroot="${found##* }"
       ;;
   esac
-  echo "$foundroot"
+  echo "${foundroot}"
 }
 
 get_cgroup_v2_path() {
@@ -140,13 +140,13 @@ get_cgroup_v2_path() {
   [ -r "/proc/self/cgroup" ] || return 1
 
   while IFS= read -r line; do
-    found=$( echo "$line" | cut -d ' ' -f 4,5 )
+    found=$( echo "${line}" | cut -d ' ' -f 4,5 )
   done << __EOF__
 $( grep -F -- '- cgroup2 ' /proc/self/mountinfo )
 __EOF__
 
   while IFS= read -r line; do
-    mountpoint=$( echo "$line" | cut -d: -f 3 )
+    mountpoint=$( echo "${line}" | cut -d: -f 3 )
 done << __EOF__
 $( grep -F -- '0::' /proc/self/cgroup )
 __EOF__
@@ -156,13 +156,13 @@ __EOF__
       return 1
       ;;
     "/")
-      foundroot="${found##* }$mountpoint"
+      foundroot="${found##* }${mountpoint}"
       ;;
-    "$mountpoint" | /../*)
+    "${mountpoint}" | /../*)
       foundroot="${found##* }"
       ;;
   esac
-  echo "$foundroot"
+  echo "${foundroot}"
 }
 
 ncpu_online=$( getconf _NPROCESSORS_ONLN )
@@ -171,18 +171,18 @@ ncpu_quota=
 ncpu_cpuset_v2=
 ncpu_quota_v2=
 
-cpuset=$( get_cgroup_v1_path "cpuset" ) && ncpu_cpuset=$( get_cpuset "$cpuset" "cpuset.effective_cpus" ) || ncpu_cpuset=$ncpu_online
-cpu=$( get_cgroup_v1_path "cpu" ) && ncpu_quota=$( get_quota "$cpu" ) || ncpu_quota=$ncpu_online
-cgroup_v2=$( get_cgroup_v2_path ) && ncpu_cpuset_v2=$( get_cpuset "$cgroup_v2" "cpuset.cpus.effective" ) || ncpu_cpuset_v2=$ncpu_online
-cgroup_v2=$( get_cgroup_v2_path ) && ncpu_quota_v2=$( get_quota_v2 "$cgroup_v2" ) || ncpu_quota_v2=$ncpu_online
+cpuset=$( get_cgroup_v1_path "cpuset" ) && ncpu_cpuset=$( get_cpuset "${cpuset}" "cpuset.effective_cpus" ) || ncpu_cpuset=${ncpu_online}
+cpu=$( get_cgroup_v1_path "cpu" ) && ncpu_quota=$( get_quota "${cpu}" ) || ncpu_quota=${ncpu_online}
+cgroup_v2=$( get_cgroup_v2_path ) && ncpu_cpuset_v2=$( get_cpuset "${cgroup_v2}" "cpuset.cpus.effective" ) || ncpu_cpuset_v2=${ncpu_online}
+cgroup_v2=$( get_cgroup_v2_path ) && ncpu_quota_v2=$( get_quota_v2 "${cgroup_v2}" ) || ncpu_quota_v2=${ncpu_online}
 
 ncpu=$( printf "%s\n%s\n%s\n%s\n%s\n" \
-               "$ncpu_online" \
-               "$ncpu_cpuset" \
-               "$ncpu_quota" \
-               "$ncpu_cpuset_v2" \
-               "$ncpu_quota_v2" \
+               "${ncpu_online}" \
+               "${ncpu_cpuset}" \
+               "${ncpu_quota}" \
+               "${ncpu_cpuset_v2}" \
+               "${ncpu_quota_v2}" \
                | sort -n \
                | head -n 1 )
 
-sed -i.bak -r 's/^(worker_processes)(.*)$/# Commented out by '"$ME"' on '"$(date)"'\n#\1\2\n\1 '"$ncpu"';/' /etc/nginx/nginx.conf
+sed -i.bak -r 's/^(worker_processes)(.*)$/# Commented out by '"${ME}"' on '"$(date)"'\n#\1\2\n\1 '"${ncpu}"';/' /etc/nginx/nginx.conf
diff --git a/mainline/debian/docker-entrypoint.sh b/mainline/debian/docker-entrypoint.sh
index 8ea04f2..cac74ec 100755
--- a/mainline/debian/docker-entrypoint.sh
+++ b/mainline/debian/docker-entrypoint.sh
@@ -1,47 +1,47 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=4:ts=4:et
 
 set -e
 
 entrypoint_log() {
     if [ -z "${NGINX_ENTRYPOINT_QUIET_LOGS:-}" ]; then
-        echo "$@"
+        echo "${@}"
     fi
 }
 
-if [ "$1" = "nginx" ] || [ "$1" = "nginx-debug" ]; then
+if [ "${1}" = "nginx" ] || [ "${1}" = "nginx-debug" ]; then
     if /usr/bin/find "/docker-entrypoint.d/" -mindepth 1 -maxdepth 1 -type f -print -quit 2>/dev/null | read v; then
-        entrypoint_log "$0: /docker-entrypoint.d/ is not empty, will attempt to perform configuration"
+        entrypoint_log "${0}: /docker-entrypoint.d/ is not empty, will attempt to perform configuration"
 
-        entrypoint_log "$0: Looking for shell scripts in /docker-entrypoint.d/"
+        entrypoint_log "${0}: Looking for shell scripts in /docker-entrypoint.d/"
         find "/docker-entrypoint.d/" -follow -type f -print | sort -V | while read -r f; do
-            case "$f" in
+            case "${f}" in
                 *.envsh)
-                    if [ -x "$f" ]; then
-                        entrypoint_log "$0: Sourcing $f";
-                        . "$f"
+                    if [ -r "${f}" ]; then
+                        entrypoint_log "${0}: Sourcing ${f}";
+                        . "${f}"
                     else
-                        # warn on shell scripts without exec bit
-                        entrypoint_log "$0: Ignoring $f, not executable";
+                        # warn on shell scripts not readable
+                        entrypoint_log "${0}: Ignoring ${f}, not readable";
                     fi
                     ;;
                 *.sh)
-                    if [ -x "$f" ]; then
-                        entrypoint_log "$0: Launching $f";
-                        "$f"
+                    if [ -x "${f}" ]; then
+                        entrypoint_log "${0}: Launching ${f}";
+                        "${f}"
                     else
                         # warn on shell scripts without exec bit
-                        entrypoint_log "$0: Ignoring $f, not executable";
+                        entrypoint_log "${0}: Ignoring ${f}, not executable";
                     fi
                     ;;
-                *) entrypoint_log "$0: Ignoring $f";;
+                *) entrypoint_log "${0}: Ignoring ${f}";;
             esac
         done
 
-        entrypoint_log "$0: Configuration complete; ready for start up"
+        entrypoint_log "${0}: Configuration complete; ready for start up"
     else
-        entrypoint_log "$0: No files found in /docker-entrypoint.d/, skipping configuration"
+        entrypoint_log "${0}: No files found in /docker-entrypoint.d/, skipping configuration"
     fi
 fi
 
-exec "$@"
+exec "${@}"
diff --git a/stable/alpine-slim/10-listen-on-ipv6-by-default.sh b/stable/alpine-slim/10-listen-on-ipv6-by-default.sh
index 29898b1..f786c00 100755
--- a/stable/alpine-slim/10-listen-on-ipv6-by-default.sh
+++ b/stable/alpine-slim/10-listen-on-ipv6-by-default.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=4:ts=4:et
 
 set -e
@@ -9,59 +9,59 @@ entrypoint_log() {
     fi
 }
 
-ME=$(basename "$0")
+ME=$(basename "${0}")
 DEFAULT_CONF_FILE="etc/nginx/conf.d/default.conf"
 
 # check if we have ipv6 available
 if [ ! -f "/proc/net/if_inet6" ]; then
-    entrypoint_log "$ME: info: ipv6 not available"
+    entrypoint_log "${ME}: info: ipv6 not available"
     exit 0
 fi
 
-if [ ! -f "/$DEFAULT_CONF_FILE" ]; then
-    entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE is not a file or does not exist"
+if [ ! -f "/${DEFAULT_CONF_FILE}" ]; then
+    entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} is not a file or does not exist"
     exit 0
 fi
 
 # check if the file can be modified, e.g. not on a r/o filesystem
-touch /$DEFAULT_CONF_FILE 2>/dev/null || { entrypoint_log "$ME: info: can not modify /$DEFAULT_CONF_FILE (read-only file system?)"; exit 0; }
+touch /${DEFAULT_CONF_FILE} 2>/dev/null || { entrypoint_log "${ME}: info: can not modify /${DEFAULT_CONF_FILE} (read-only file system?)"; exit 0; }
 
 # check if the file is already modified, e.g. on a container restart
-grep -q "listen  \[::]\:8080;" /$DEFAULT_CONF_FILE && { entrypoint_log "$ME: info: IPv6 listen already enabled"; exit 0; }
+grep -q "listen  \[::]\:8080;" /${DEFAULT_CONF_FILE} && { entrypoint_log "${ME}: info: IPv6 listen already enabled"; exit 0; }
 
 if [ -f "/etc/os-release" ]; then
     . /etc/os-release
 else
-    entrypoint_log "$ME: info: can not guess the operating system"
+    entrypoint_log "${ME}: info: can not guess the operating system"
     exit 0
 fi
 
-entrypoint_log "$ME: info: Getting the checksum of /$DEFAULT_CONF_FILE"
+entrypoint_log "${ME}: info: Getting the checksum of /${DEFAULT_CONF_FILE}"
 
-case "$ID" in
+case "${ID}" in
     "debian")
-        CHECKSUM=$(dpkg-query --show --showformat='${Conffiles}\n' nginx | grep $DEFAULT_CONF_FILE | cut -d' ' -f 3)
-        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | md5sum -c - >/dev/null 2>&1 || {
-            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
+        CHECKSUM=$(dpkg-query --show --showformat='${Conffiles}\n' nginx | grep ${DEFAULT_CONF_FILE} | cut -d' ' -f 3)
+        echo "${CHECKSUM}  /${DEFAULT_CONF_FILE}" | md5sum -c - >/dev/null 2>&1 || {
+            entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} differs from the packaged version"
             exit 0
         }
         ;;
     "alpine")
-        CHECKSUM=$(apk manifest nginx 2>/dev/null| grep $DEFAULT_CONF_FILE | cut -d' ' -f 1 | cut -d ':' -f 2)
-        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | sha1sum -c - >/dev/null 2>&1 || {
-            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
+        CHECKSUM=$(apk manifest nginx 2>/dev/null| grep ${DEFAULT_CONF_FILE} | cut -d' ' -f 1 | cut -d ':' -f 2)
+        echo "${CHECKSUM}  /${DEFAULT_CONF_FILE}" | sha1sum -c - >/dev/null 2>&1 || {
+            entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} differs from the packaged version"
             exit 0
         }
         ;;
     *)
-        entrypoint_log "$ME: info: Unsupported distribution"
+        entrypoint_log "${ME}: info: Unsupported distribution"
         exit 0
         ;;
 esac
 
 # enable ipv6 on default.conf listen sockets
-sed -i -E 's,listen       8080;,listen       8080;\n    listen  [::]:8080;,' /$DEFAULT_CONF_FILE
+sed -i -E 's,listen       8080;,listen       8080;\n    listen  [::]:8080;,' /${DEFAULT_CONF_FILE}
 
-entrypoint_log "$ME: info: Enabled listen on IPv6 in /$DEFAULT_CONF_FILE"
+entrypoint_log "${ME}: info: Enabled listen on IPv6 in /${DEFAULT_CONF_FILE}"
 
 exit 0
diff --git a/stable/alpine-slim/15-local-resolvers.envsh b/stable/alpine-slim/15-local-resolvers.envsh
index e830dda..87d88ea 100755
--- a/stable/alpine-slim/15-local-resolvers.envsh
+++ b/stable/alpine-slim/15-local-resolvers.envsh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=2:ts=2:sts=2:et
 
 set -eu
diff --git a/stable/alpine-slim/20-envsubst-on-templates.sh b/stable/alpine-slim/20-envsubst-on-templates.sh
index 6938405..febbc7e 100755
--- a/stable/alpine-slim/20-envsubst-on-templates.sh
+++ b/stable/alpine-slim/20-envsubst-on-templates.sh
@@ -1,8 +1,8 @@
-#!/bin/sh
+#!/usr/bin/env sh
 
 set -e
 
-ME=$(basename "$0")
+ME=$(basename "${0}")
 
 entrypoint_log() {
   if [ -z "${NGINX_ENTRYPOINT_QUIET_LOGS:-}" ]; then
@@ -13,16 +13,16 @@ entrypoint_log() {
 add_stream_block() {
   local conffile="/etc/nginx/nginx.conf"
 
-  if grep -q -E "\s*stream\s*\{" "$conffile"; then
-    entrypoint_log "$ME: $conffile contains a stream block; include $stream_output_dir/*.conf to enable stream templates"
+  if grep -q -E "\s*stream\s*\{" "${conffile}"; then
+    entrypoint_log "${ME}: ${conffile} contains a stream block; include ${stream_output_dir}/*.conf to enable stream templates"
   else
     # check if the file can be modified, e.g. not on a r/o filesystem
-    touch "$conffile" 2>/dev/null || { entrypoint_log "$ME: info: can not modify $conffile (read-only file system?)"; exit 0; }
-    entrypoint_log "$ME: Appending stream block to $conffile to include $stream_output_dir/*.conf"
-    cat << END >> "$conffile"
-# added by "$ME" on "$(date)"
+    touch "${conffile}" 2>/dev/null || { entrypoint_log "${ME}: info: can not modify ${conffile} (read-only file system?)"; exit 0; }
+    entrypoint_log "${ME}: Appending stream block to ${conffile} to include ${stream_output_dir}/*.conf"
+    cat << END >> "${conffile}"
+# added by "${ME}" on "$(date)"
 stream {
-  include $stream_output_dir/*.conf;
+  include ${stream_output_dir}/*.conf;
 }
 END
   fi
@@ -38,37 +38,37 @@ auto_envsubst() {
 
   local template defined_envs relative_path output_path subdir
   defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
-  [ -d "$template_dir" ] || return 0
-  if [ ! -w "$output_dir" ]; then
-    entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"
+  [ -d "${template_dir}" ] || return 0
+  if [ ! -w "${output_dir}" ]; then
+    entrypoint_log "${ME}: ERROR: ${template_dir} exists, but ${output_dir} is not writable"
     return 0
   fi
-  find "$template_dir" -follow -type f -name "*$suffix" -print | while read -r template; do
-    relative_path="${template#"$template_dir/"}"
-    output_path="$output_dir/${relative_path%"$suffix"}"
-    subdir=$(dirname "$relative_path")
+  find "${template_dir}" -follow -type f -name "*${suffix}" -print | while read -r template; do
+    relative_path="${template#"${template_dir}/"}"
+    output_path="${output_dir}/${relative_path%"${suffix}"}"
+    subdir=$(dirname "${relative_path}")
     # create a subdirectory where the template file exists
-    mkdir -p "$output_dir/$subdir"
-    entrypoint_log "$ME: Running envsubst on $template to $output_path"
-    envsubst "$defined_envs" < "$template" > "$output_path"
+    mkdir -p "${output_dir}/${subdir}"
+    entrypoint_log "${ME}: Running envsubst on ${template} to ${output_path}"
+    envsubst "${defined_envs}" < "${template}" > "${output_path}"
   done
 
   # Print the first file with the stream suffix, this will be false if there are none
-  if test -n "$(find "$template_dir" -name "*$stream_suffix" -print -quit)"; then
-    mkdir -p "$stream_output_dir"
-    if [ ! -w "$stream_output_dir" ]; then
-      entrypoint_log "$ME: ERROR: $template_dir exists, but $stream_output_dir is not writable"
+  if test -n "$(find "${template_dir}" -name "*${stream_suffix}" -print -quit)"; then
+    mkdir -p "${stream_output_dir}"
+    if [ ! -w "${stream_output_dir}" ]; then
+      entrypoint_log "${ME}: ERROR: ${template_dir} exists, but ${stream_output_dir} is not writable"
       return 0
     fi
     add_stream_block
-    find "$template_dir" -follow -type f -name "*$stream_suffix" -print | while read -r template; do
-      relative_path="${template#"$template_dir/"}"
-      output_path="$stream_output_dir/${relative_path%"$stream_suffix"}"
-      subdir=$(dirname "$relative_path")
+    find "${template_dir}" -follow -type f -name "*${stream_suffix}" -print | while read -r template; do
+      relative_path="${template#"${template_dir}/"}"
+      output_path="${stream_output_dir}/${relative_path%"${stream_suffix}"}"
+      subdir=$(dirname "${relative_path}")
       # create a subdirectory where the template file exists
-      mkdir -p "$stream_output_dir/$subdir"
-      entrypoint_log "$ME: Running envsubst on $template to $output_path"
-      envsubst "$defined_envs" < "$template" > "$output_path"
+      mkdir -p "${stream_output_dir}/${subdir}"
+      entrypoint_log "${ME}: Running envsubst on ${template} to ${output_path}"
+      envsubst "${defined_envs}" < "${template}" > "${output_path}"
     done
   fi
 }
diff --git a/stable/alpine-slim/30-tune-worker-processes.sh b/stable/alpine-slim/30-tune-worker-processes.sh
index defb994..df3885a 100755
--- a/stable/alpine-slim/30-tune-worker-processes.sh
+++ b/stable/alpine-slim/30-tune-worker-processes.sh
@@ -1,31 +1,31 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=2:ts=2:sts=2:et
 
 set -eu
 
 LC_ALL=C
-ME=$(basename "$0")
+ME=$(basename "${0}")
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 
 [ "${NGINX_ENTRYPOINT_WORKER_PROCESSES_AUTOTUNE:-}" ] || exit 0
 
-touch /etc/nginx/nginx.conf 2>/dev/null || { echo >&2 "$ME: error: can not modify /etc/nginx/nginx.conf (read-only file system?)"; exit 0; }
+touch /etc/nginx/nginx.conf 2>/dev/null || { echo >&2 "\${ME}: error: can not modify /etc/nginx/nginx.conf (read-only file system?)"; exit 0; }
 
 ceildiv() {
-  num=$1
-  div=$2
+  num=${1}
+  div=${2}
   echo $(( (num + div - 1) / div ))
 }
 
 get_cpuset() {
-  cpusetroot=$1
-  cpusetfile=$2
+  cpusetroot=${1}
+  cpusetfile=${2}
   ncpu=0
-  [ -f "$cpusetroot/$cpusetfile" ] || return 1
-  for token in $( tr ',' ' ' < "$cpusetroot/$cpusetfile" ); do
-    case "$token" in
+  [ -f "${cpusetroot}/${cpusetfile}" ] || return 1
+  for token in $( tr ',' ' ' < "${cpusetroot}/${cpusetfile}" ); do
+    case "${token}" in
       *-*)
-        count=$( seq $(echo "$token" | tr '-' ' ') | wc -l )
+        count=$( seq $(echo "${token}" | tr '-' ' ') | wc -l )
         ncpu=$(( ncpu+count ))
         ;;
       *)
@@ -33,38 +33,38 @@ get_cpuset() {
         ;;
     esac
   done
-  echo "$ncpu"
+  echo "${ncpu}"
 }
 
 get_quota() {
-  cpuroot=$1
+  cpuroot=${1}
   ncpu=0
-  [ -f "$cpuroot/cpu.cfs_quota_us" ] || return 1
-  [ -f "$cpuroot/cpu.cfs_period_us" ] || return 1
-  cfs_quota=$( cat "$cpuroot/cpu.cfs_quota_us" )
-  cfs_period=$( cat "$cpuroot/cpu.cfs_period_us" )
-  [ "$cfs_quota" = "-1" ] && return 1
-  [ "$cfs_period" = "0" ] && return 1
-  ncpu=$( ceildiv "$cfs_quota" "$cfs_period" )
-  [ "$ncpu" -gt 0 ] || return 1
-  echo "$ncpu"
+  [ -f "${cpuroot}/cpu.cfs_quota_us" ] || return 1
+  [ -f "${cpuroot}/cpu.cfs_period_us" ] || return 1
+  cfs_quota=$( cat "${cpuroot}/cpu.cfs_quota_us" )
+  cfs_period=$( cat "${cpuroot}/cpu.cfs_period_us" )
+  [ "${cfs_quota}" = "-1" ] && return 1
+  [ "${cfs_period}" = "0" ] && return 1
+  ncpu=$( ceildiv "${cfs_quota}" "${cfs_period}" )
+  [ "${ncpu}" -gt 0 ] || return 1
+  echo "${ncpu}"
 }
 
 get_quota_v2() {
-  cpuroot=$1
+  cpuroot=${1}
   ncpu=0
-  [ -f "$cpuroot/cpu.max" ] || return 1
-  cfs_quota=$( cut -d' ' -f 1 < "$cpuroot/cpu.max" )
-  cfs_period=$( cut -d' ' -f 2 < "$cpuroot/cpu.max" )
-  [ "$cfs_quota" = "max" ] && return 1
-  [ "$cfs_period" = "0" ] && return 1
-  ncpu=$( ceildiv "$cfs_quota" "$cfs_period" )
-  [ "$ncpu" -gt 0 ] || return 1
-  echo "$ncpu"
+  [ -f "${cpuroot}/cpu.max" ] || return 1
+  cfs_quota=$( cut -d' ' -f 1 < "${cpuroot}/cpu.max" )
+  cfs_period=$( cut -d' ' -f 2 < "${cpuroot}/cpu.max" )
+  [ "${cfs_quota}" = "max" ] && return 1
+  [ "${cfs_period}" = "0" ] && return 1
+  ncpu=$( ceildiv "${cfs_quota}" "${cfs_period}" )
+  [ "${ncpu}" -gt 0 ] || return 1
+  echo "${ncpu}"
 }
 
 get_cgroup_v1_path() {
-  needle=$1
+  needle=${1}
   found=
   foundroot=
   mountpoint=
@@ -73,21 +73,21 @@ get_cgroup_v1_path() {
   [ -r "/proc/self/cgroup" ] || return 1
 
   while IFS= read -r line; do
-    case "$needle" in
+    case "${needle}" in
       "cpuset")
-        case "$line" in
+        case "${line}" in
           *cpuset*)
-            found=$( echo "$line" | cut -d ' ' -f 4,5 )
+            found=$( echo "${line}" | cut -d ' ' -f 4,5 )
             break
             ;;
         esac
         ;;
       "cpu")
-        case "$line" in
+        case "${line}" in
           *cpuset*)
             ;;
           *cpu,cpuacct*|*cpuacct,cpu|*cpuacct*|*cpu*)
-            found=$( echo "$line" | cut -d ' ' -f 4,5 )
+            found=$( echo "${line}" | cut -d ' ' -f 4,5 )
             break
             ;;
         esac
@@ -97,20 +97,20 @@ $( grep -F -- '- cgroup ' /proc/self/mountinfo )
 __EOF__
 
   while IFS= read -r line; do
-    controller=$( echo "$line" | cut -d: -f 2 )
-    case "$needle" in
+    controller=$( echo "${line}" | cut -d: -f 2 )
+    case "${needle}" in
       "cpuset")
-        case "$controller" in
+        case "${controller}" in
           cpuset)
-            mountpoint=$( echo "$line" | cut -d: -f 3 )
+            mountpoint=$( echo "${line}" | cut -d: -f 3 )
             break
             ;;
         esac
         ;;
       "cpu")
-        case "$controller" in
+        case "${controller}" in
           cpu,cpuacct|cpuacct,cpu|cpuacct|cpu)
-            mountpoint=$( echo "$line" | cut -d: -f 3 )
+            mountpoint=$( echo "${line}" | cut -d: -f 3 )
             break
             ;;
         esac
@@ -122,13 +122,13 @@ __EOF__
 
   case "${found%% *}" in
     "/")
-      foundroot="${found##* }$mountpoint"
+      foundroot="${found##* }${mountpoint}"
       ;;
-    "$mountpoint")
+    "${mountpoint}")
       foundroot="${found##* }"
       ;;
   esac
-  echo "$foundroot"
+  echo "${foundroot}"
 }
 
 get_cgroup_v2_path() {
@@ -140,13 +140,13 @@ get_cgroup_v2_path() {
   [ -r "/proc/self/cgroup" ] || return 1
 
   while IFS= read -r line; do
-    found=$( echo "$line" | cut -d ' ' -f 4,5 )
+    found=$( echo "${line}" | cut -d ' ' -f 4,5 )
   done << __EOF__
 $( grep -F -- '- cgroup2 ' /proc/self/mountinfo )
 __EOF__
 
   while IFS= read -r line; do
-    mountpoint=$( echo "$line" | cut -d: -f 3 )
+    mountpoint=$( echo "${line}" | cut -d: -f 3 )
 done << __EOF__
 $( grep -F -- '0::' /proc/self/cgroup )
 __EOF__
@@ -156,13 +156,13 @@ __EOF__
       return 1
       ;;
     "/")
-      foundroot="${found##* }$mountpoint"
+      foundroot="${found##* }${mountpoint}"
       ;;
-    "$mountpoint" | /../*)
+    "${mountpoint}" | /../*)
       foundroot="${found##* }"
       ;;
   esac
-  echo "$foundroot"
+  echo "${foundroot}"
 }
 
 ncpu_online=$( getconf _NPROCESSORS_ONLN )
@@ -171,18 +171,18 @@ ncpu_quota=
 ncpu_cpuset_v2=
 ncpu_quota_v2=
 
-cpuset=$( get_cgroup_v1_path "cpuset" ) && ncpu_cpuset=$( get_cpuset "$cpuset" "cpuset.effective_cpus" ) || ncpu_cpuset=$ncpu_online
-cpu=$( get_cgroup_v1_path "cpu" ) && ncpu_quota=$( get_quota "$cpu" ) || ncpu_quota=$ncpu_online
-cgroup_v2=$( get_cgroup_v2_path ) && ncpu_cpuset_v2=$( get_cpuset "$cgroup_v2" "cpuset.cpus.effective" ) || ncpu_cpuset_v2=$ncpu_online
-cgroup_v2=$( get_cgroup_v2_path ) && ncpu_quota_v2=$( get_quota_v2 "$cgroup_v2" ) || ncpu_quota_v2=$ncpu_online
+cpuset=$( get_cgroup_v1_path "cpuset" ) && ncpu_cpuset=$( get_cpuset "${cpuset}" "cpuset.effective_cpus" ) || ncpu_cpuset=${ncpu_online}
+cpu=$( get_cgroup_v1_path "cpu" ) && ncpu_quota=$( get_quota "${cpu}" ) || ncpu_quota=${ncpu_online}
+cgroup_v2=$( get_cgroup_v2_path ) && ncpu_cpuset_v2=$( get_cpuset "${cgroup_v2}" "cpuset.cpus.effective" ) || ncpu_cpuset_v2=${ncpu_online}
+cgroup_v2=$( get_cgroup_v2_path ) && ncpu_quota_v2=$( get_quota_v2 "${cgroup_v2}" ) || ncpu_quota_v2=${ncpu_online}
 
 ncpu=$( printf "%s\n%s\n%s\n%s\n%s\n" \
-               "$ncpu_online" \
-               "$ncpu_cpuset" \
-               "$ncpu_quota" \
-               "$ncpu_cpuset_v2" \
-               "$ncpu_quota_v2" \
+               "${ncpu_online}" \
+               "${ncpu_cpuset}" \
+               "${ncpu_quota}" \
+               "${ncpu_cpuset_v2}" \
+               "${ncpu_quota_v2}" \
                | sort -n \
                | head -n 1 )
 
-sed -i.bak -r 's/^(worker_processes)(.*)$/# Commented out by '"$ME"' on '"$(date)"'\n#\1\2\n\1 '"$ncpu"';/' /etc/nginx/nginx.conf
+sed -i.bak -r 's/^(worker_processes)(.*)$/# Commented out by '"${ME}"' on '"$(date)"'\n#\1\2\n\1 '"${ncpu}"';/' /etc/nginx/nginx.conf
diff --git a/stable/alpine-slim/docker-entrypoint.sh b/stable/alpine-slim/docker-entrypoint.sh
index 8ea04f2..cac74ec 100755
--- a/stable/alpine-slim/docker-entrypoint.sh
+++ b/stable/alpine-slim/docker-entrypoint.sh
@@ -1,47 +1,47 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=4:ts=4:et
 
 set -e
 
 entrypoint_log() {
     if [ -z "${NGINX_ENTRYPOINT_QUIET_LOGS:-}" ]; then
-        echo "$@"
+        echo "${@}"
     fi
 }
 
-if [ "$1" = "nginx" ] || [ "$1" = "nginx-debug" ]; then
+if [ "${1}" = "nginx" ] || [ "${1}" = "nginx-debug" ]; then
     if /usr/bin/find "/docker-entrypoint.d/" -mindepth 1 -maxdepth 1 -type f -print -quit 2>/dev/null | read v; then
-        entrypoint_log "$0: /docker-entrypoint.d/ is not empty, will attempt to perform configuration"
+        entrypoint_log "${0}: /docker-entrypoint.d/ is not empty, will attempt to perform configuration"
 
-        entrypoint_log "$0: Looking for shell scripts in /docker-entrypoint.d/"
+        entrypoint_log "${0}: Looking for shell scripts in /docker-entrypoint.d/"
         find "/docker-entrypoint.d/" -follow -type f -print | sort -V | while read -r f; do
-            case "$f" in
+            case "${f}" in
                 *.envsh)
-                    if [ -x "$f" ]; then
-                        entrypoint_log "$0: Sourcing $f";
-                        . "$f"
+                    if [ -r "${f}" ]; then
+                        entrypoint_log "${0}: Sourcing ${f}";
+                        . "${f}"
                     else
-                        # warn on shell scripts without exec bit
-                        entrypoint_log "$0: Ignoring $f, not executable";
+                        # warn on shell scripts not readable
+                        entrypoint_log "${0}: Ignoring ${f}, not readable";
                     fi
                     ;;
                 *.sh)
-                    if [ -x "$f" ]; then
-                        entrypoint_log "$0: Launching $f";
-                        "$f"
+                    if [ -x "${f}" ]; then
+                        entrypoint_log "${0}: Launching ${f}";
+                        "${f}"
                     else
                         # warn on shell scripts without exec bit
-                        entrypoint_log "$0: Ignoring $f, not executable";
+                        entrypoint_log "${0}: Ignoring ${f}, not executable";
                     fi
                     ;;
-                *) entrypoint_log "$0: Ignoring $f";;
+                *) entrypoint_log "${0}: Ignoring ${f}";;
             esac
         done
 
-        entrypoint_log "$0: Configuration complete; ready for start up"
+        entrypoint_log "${0}: Configuration complete; ready for start up"
     else
-        entrypoint_log "$0: No files found in /docker-entrypoint.d/, skipping configuration"
+        entrypoint_log "${0}: No files found in /docker-entrypoint.d/, skipping configuration"
     fi
 fi
 
-exec "$@"
+exec "${@}"
diff --git a/stable/debian/10-listen-on-ipv6-by-default.sh b/stable/debian/10-listen-on-ipv6-by-default.sh
index 29898b1..f786c00 100755
--- a/stable/debian/10-listen-on-ipv6-by-default.sh
+++ b/stable/debian/10-listen-on-ipv6-by-default.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=4:ts=4:et
 
 set -e
@@ -9,59 +9,59 @@ entrypoint_log() {
     fi
 }
 
-ME=$(basename "$0")
+ME=$(basename "${0}")
 DEFAULT_CONF_FILE="etc/nginx/conf.d/default.conf"
 
 # check if we have ipv6 available
 if [ ! -f "/proc/net/if_inet6" ]; then
-    entrypoint_log "$ME: info: ipv6 not available"
+    entrypoint_log "${ME}: info: ipv6 not available"
     exit 0
 fi
 
-if [ ! -f "/$DEFAULT_CONF_FILE" ]; then
-    entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE is not a file or does not exist"
+if [ ! -f "/${DEFAULT_CONF_FILE}" ]; then
+    entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} is not a file or does not exist"
     exit 0
 fi
 
 # check if the file can be modified, e.g. not on a r/o filesystem
-touch /$DEFAULT_CONF_FILE 2>/dev/null || { entrypoint_log "$ME: info: can not modify /$DEFAULT_CONF_FILE (read-only file system?)"; exit 0; }
+touch /${DEFAULT_CONF_FILE} 2>/dev/null || { entrypoint_log "${ME}: info: can not modify /${DEFAULT_CONF_FILE} (read-only file system?)"; exit 0; }
 
 # check if the file is already modified, e.g. on a container restart
-grep -q "listen  \[::]\:8080;" /$DEFAULT_CONF_FILE && { entrypoint_log "$ME: info: IPv6 listen already enabled"; exit 0; }
+grep -q "listen  \[::]\:8080;" /${DEFAULT_CONF_FILE} && { entrypoint_log "${ME}: info: IPv6 listen already enabled"; exit 0; }
 
 if [ -f "/etc/os-release" ]; then
     . /etc/os-release
 else
-    entrypoint_log "$ME: info: can not guess the operating system"
+    entrypoint_log "${ME}: info: can not guess the operating system"
     exit 0
 fi
 
-entrypoint_log "$ME: info: Getting the checksum of /$DEFAULT_CONF_FILE"
+entrypoint_log "${ME}: info: Getting the checksum of /${DEFAULT_CONF_FILE}"
 
-case "$ID" in
+case "${ID}" in
     "debian")
-        CHECKSUM=$(dpkg-query --show --showformat='${Conffiles}\n' nginx | grep $DEFAULT_CONF_FILE | cut -d' ' -f 3)
-        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | md5sum -c - >/dev/null 2>&1 || {
-            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
+        CHECKSUM=$(dpkg-query --show --showformat='${Conffiles}\n' nginx | grep ${DEFAULT_CONF_FILE} | cut -d' ' -f 3)
+        echo "${CHECKSUM}  /${DEFAULT_CONF_FILE}" | md5sum -c - >/dev/null 2>&1 || {
+            entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} differs from the packaged version"
             exit 0
         }
         ;;
     "alpine")
-        CHECKSUM=$(apk manifest nginx 2>/dev/null| grep $DEFAULT_CONF_FILE | cut -d' ' -f 1 | cut -d ':' -f 2)
-        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | sha1sum -c - >/dev/null 2>&1 || {
-            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
+        CHECKSUM=$(apk manifest nginx 2>/dev/null| grep ${DEFAULT_CONF_FILE} | cut -d' ' -f 1 | cut -d ':' -f 2)
+        echo "${CHECKSUM}  /${DEFAULT_CONF_FILE}" | sha1sum -c - >/dev/null 2>&1 || {
+            entrypoint_log "${ME}: info: /${DEFAULT_CONF_FILE} differs from the packaged version"
             exit 0
         }
         ;;
     *)
-        entrypoint_log "$ME: info: Unsupported distribution"
+        entrypoint_log "${ME}: info: Unsupported distribution"
         exit 0
         ;;
 esac
 
 # enable ipv6 on default.conf listen sockets
-sed -i -E 's,listen       8080;,listen       8080;\n    listen  [::]:8080;,' /$DEFAULT_CONF_FILE
+sed -i -E 's,listen       8080;,listen       8080;\n    listen  [::]:8080;,' /${DEFAULT_CONF_FILE}
 
-entrypoint_log "$ME: info: Enabled listen on IPv6 in /$DEFAULT_CONF_FILE"
+entrypoint_log "${ME}: info: Enabled listen on IPv6 in /${DEFAULT_CONF_FILE}"
 
 exit 0
diff --git a/stable/debian/15-local-resolvers.envsh b/stable/debian/15-local-resolvers.envsh
index e830dda..87d88ea 100755
--- a/stable/debian/15-local-resolvers.envsh
+++ b/stable/debian/15-local-resolvers.envsh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=2:ts=2:sts=2:et
 
 set -eu
diff --git a/stable/debian/20-envsubst-on-templates.sh b/stable/debian/20-envsubst-on-templates.sh
index 6938405..febbc7e 100755
--- a/stable/debian/20-envsubst-on-templates.sh
+++ b/stable/debian/20-envsubst-on-templates.sh
@@ -1,8 +1,8 @@
-#!/bin/sh
+#!/usr/bin/env sh
 
 set -e
 
-ME=$(basename "$0")
+ME=$(basename "${0}")
 
 entrypoint_log() {
   if [ -z "${NGINX_ENTRYPOINT_QUIET_LOGS:-}" ]; then
@@ -13,16 +13,16 @@ entrypoint_log() {
 add_stream_block() {
   local conffile="/etc/nginx/nginx.conf"
 
-  if grep -q -E "\s*stream\s*\{" "$conffile"; then
-    entrypoint_log "$ME: $conffile contains a stream block; include $stream_output_dir/*.conf to enable stream templates"
+  if grep -q -E "\s*stream\s*\{" "${conffile}"; then
+    entrypoint_log "${ME}: ${conffile} contains a stream block; include ${stream_output_dir}/*.conf to enable stream templates"
   else
     # check if the file can be modified, e.g. not on a r/o filesystem
-    touch "$conffile" 2>/dev/null || { entrypoint_log "$ME: info: can not modify $conffile (read-only file system?)"; exit 0; }
-    entrypoint_log "$ME: Appending stream block to $conffile to include $stream_output_dir/*.conf"
-    cat << END >> "$conffile"
-# added by "$ME" on "$(date)"
+    touch "${conffile}" 2>/dev/null || { entrypoint_log "${ME}: info: can not modify ${conffile} (read-only file system?)"; exit 0; }
+    entrypoint_log "${ME}: Appending stream block to ${conffile} to include ${stream_output_dir}/*.conf"
+    cat << END >> "${conffile}"
+# added by "${ME}" on "$(date)"
 stream {
-  include $stream_output_dir/*.conf;
+  include ${stream_output_dir}/*.conf;
 }
 END
   fi
@@ -38,37 +38,37 @@ auto_envsubst() {
 
   local template defined_envs relative_path output_path subdir
   defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
-  [ -d "$template_dir" ] || return 0
-  if [ ! -w "$output_dir" ]; then
-    entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"
+  [ -d "${template_dir}" ] || return 0
+  if [ ! -w "${output_dir}" ]; then
+    entrypoint_log "${ME}: ERROR: ${template_dir} exists, but ${output_dir} is not writable"
     return 0
   fi
-  find "$template_dir" -follow -type f -name "*$suffix" -print | while read -r template; do
-    relative_path="${template#"$template_dir/"}"
-    output_path="$output_dir/${relative_path%"$suffix"}"
-    subdir=$(dirname "$relative_path")
+  find "${template_dir}" -follow -type f -name "*${suffix}" -print | while read -r template; do
+    relative_path="${template#"${template_dir}/"}"
+    output_path="${output_dir}/${relative_path%"${suffix}"}"
+    subdir=$(dirname "${relative_path}")
     # create a subdirectory where the template file exists
-    mkdir -p "$output_dir/$subdir"
-    entrypoint_log "$ME: Running envsubst on $template to $output_path"
-    envsubst "$defined_envs" < "$template" > "$output_path"
+    mkdir -p "${output_dir}/${subdir}"
+    entrypoint_log "${ME}: Running envsubst on ${template} to ${output_path}"
+    envsubst "${defined_envs}" < "${template}" > "${output_path}"
   done
 
   # Print the first file with the stream suffix, this will be false if there are none
-  if test -n "$(find "$template_dir" -name "*$stream_suffix" -print -quit)"; then
-    mkdir -p "$stream_output_dir"
-    if [ ! -w "$stream_output_dir" ]; then
-      entrypoint_log "$ME: ERROR: $template_dir exists, but $stream_output_dir is not writable"
+  if test -n "$(find "${template_dir}" -name "*${stream_suffix}" -print -quit)"; then
+    mkdir -p "${stream_output_dir}"
+    if [ ! -w "${stream_output_dir}" ]; then
+      entrypoint_log "${ME}: ERROR: ${template_dir} exists, but ${stream_output_dir} is not writable"
       return 0
     fi
     add_stream_block
-    find "$template_dir" -follow -type f -name "*$stream_suffix" -print | while read -r template; do
-      relative_path="${template#"$template_dir/"}"
-      output_path="$stream_output_dir/${relative_path%"$stream_suffix"}"
-      subdir=$(dirname "$relative_path")
+    find "${template_dir}" -follow -type f -name "*${stream_suffix}" -print | while read -r template; do
+      relative_path="${template#"${template_dir}/"}"
+      output_path="${stream_output_dir}/${relative_path%"${stream_suffix}"}"
+      subdir=$(dirname "${relative_path}")
       # create a subdirectory where the template file exists
-      mkdir -p "$stream_output_dir/$subdir"
-      entrypoint_log "$ME: Running envsubst on $template to $output_path"
-      envsubst "$defined_envs" < "$template" > "$output_path"
+      mkdir -p "${stream_output_dir}/${subdir}"
+      entrypoint_log "${ME}: Running envsubst on ${template} to ${output_path}"
+      envsubst "${defined_envs}" < "${template}" > "${output_path}"
     done
   fi
 }
diff --git a/stable/debian/30-tune-worker-processes.sh b/stable/debian/30-tune-worker-processes.sh
index defb994..df3885a 100755
--- a/stable/debian/30-tune-worker-processes.sh
+++ b/stable/debian/30-tune-worker-processes.sh
@@ -1,31 +1,31 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=2:ts=2:sts=2:et
 
 set -eu
 
 LC_ALL=C
-ME=$(basename "$0")
+ME=$(basename "${0}")
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 
 [ "${NGINX_ENTRYPOINT_WORKER_PROCESSES_AUTOTUNE:-}" ] || exit 0
 
-touch /etc/nginx/nginx.conf 2>/dev/null || { echo >&2 "$ME: error: can not modify /etc/nginx/nginx.conf (read-only file system?)"; exit 0; }
+touch /etc/nginx/nginx.conf 2>/dev/null || { echo >&2 "\${ME}: error: can not modify /etc/nginx/nginx.conf (read-only file system?)"; exit 0; }
 
 ceildiv() {
-  num=$1
-  div=$2
+  num=${1}
+  div=${2}
   echo $(( (num + div - 1) / div ))
 }
 
 get_cpuset() {
-  cpusetroot=$1
-  cpusetfile=$2
+  cpusetroot=${1}
+  cpusetfile=${2}
   ncpu=0
-  [ -f "$cpusetroot/$cpusetfile" ] || return 1
-  for token in $( tr ',' ' ' < "$cpusetroot/$cpusetfile" ); do
-    case "$token" in
+  [ -f "${cpusetroot}/${cpusetfile}" ] || return 1
+  for token in $( tr ',' ' ' < "${cpusetroot}/${cpusetfile}" ); do
+    case "${token}" in
       *-*)
-        count=$( seq $(echo "$token" | tr '-' ' ') | wc -l )
+        count=$( seq $(echo "${token}" | tr '-' ' ') | wc -l )
         ncpu=$(( ncpu+count ))
         ;;
       *)
@@ -33,38 +33,38 @@ get_cpuset() {
         ;;
     esac
   done
-  echo "$ncpu"
+  echo "${ncpu}"
 }
 
 get_quota() {
-  cpuroot=$1
+  cpuroot=${1}
   ncpu=0
-  [ -f "$cpuroot/cpu.cfs_quota_us" ] || return 1
-  [ -f "$cpuroot/cpu.cfs_period_us" ] || return 1
-  cfs_quota=$( cat "$cpuroot/cpu.cfs_quota_us" )
-  cfs_period=$( cat "$cpuroot/cpu.cfs_period_us" )
-  [ "$cfs_quota" = "-1" ] && return 1
-  [ "$cfs_period" = "0" ] && return 1
-  ncpu=$( ceildiv "$cfs_quota" "$cfs_period" )
-  [ "$ncpu" -gt 0 ] || return 1
-  echo "$ncpu"
+  [ -f "${cpuroot}/cpu.cfs_quota_us" ] || return 1
+  [ -f "${cpuroot}/cpu.cfs_period_us" ] || return 1
+  cfs_quota=$( cat "${cpuroot}/cpu.cfs_quota_us" )
+  cfs_period=$( cat "${cpuroot}/cpu.cfs_period_us" )
+  [ "${cfs_quota}" = "-1" ] && return 1
+  [ "${cfs_period}" = "0" ] && return 1
+  ncpu=$( ceildiv "${cfs_quota}" "${cfs_period}" )
+  [ "${ncpu}" -gt 0 ] || return 1
+  echo "${ncpu}"
 }
 
 get_quota_v2() {
-  cpuroot=$1
+  cpuroot=${1}
   ncpu=0
-  [ -f "$cpuroot/cpu.max" ] || return 1
-  cfs_quota=$( cut -d' ' -f 1 < "$cpuroot/cpu.max" )
-  cfs_period=$( cut -d' ' -f 2 < "$cpuroot/cpu.max" )
-  [ "$cfs_quota" = "max" ] && return 1
-  [ "$cfs_period" = "0" ] && return 1
-  ncpu=$( ceildiv "$cfs_quota" "$cfs_period" )
-  [ "$ncpu" -gt 0 ] || return 1
-  echo "$ncpu"
+  [ -f "${cpuroot}/cpu.max" ] || return 1
+  cfs_quota=$( cut -d' ' -f 1 < "${cpuroot}/cpu.max" )
+  cfs_period=$( cut -d' ' -f 2 < "${cpuroot}/cpu.max" )
+  [ "${cfs_quota}" = "max" ] && return 1
+  [ "${cfs_period}" = "0" ] && return 1
+  ncpu=$( ceildiv "${cfs_quota}" "${cfs_period}" )
+  [ "${ncpu}" -gt 0 ] || return 1
+  echo "${ncpu}"
 }
 
 get_cgroup_v1_path() {
-  needle=$1
+  needle=${1}
   found=
   foundroot=
   mountpoint=
@@ -73,21 +73,21 @@ get_cgroup_v1_path() {
   [ -r "/proc/self/cgroup" ] || return 1
 
   while IFS= read -r line; do
-    case "$needle" in
+    case "${needle}" in
       "cpuset")
-        case "$line" in
+        case "${line}" in
           *cpuset*)
-            found=$( echo "$line" | cut -d ' ' -f 4,5 )
+            found=$( echo "${line}" | cut -d ' ' -f 4,5 )
             break
             ;;
         esac
         ;;
       "cpu")
-        case "$line" in
+        case "${line}" in
           *cpuset*)
             ;;
           *cpu,cpuacct*|*cpuacct,cpu|*cpuacct*|*cpu*)
-            found=$( echo "$line" | cut -d ' ' -f 4,5 )
+            found=$( echo "${line}" | cut -d ' ' -f 4,5 )
             break
             ;;
         esac
@@ -97,20 +97,20 @@ $( grep -F -- '- cgroup ' /proc/self/mountinfo )
 __EOF__
 
   while IFS= read -r line; do
-    controller=$( echo "$line" | cut -d: -f 2 )
-    case "$needle" in
+    controller=$( echo "${line}" | cut -d: -f 2 )
+    case "${needle}" in
       "cpuset")
-        case "$controller" in
+        case "${controller}" in
           cpuset)
-            mountpoint=$( echo "$line" | cut -d: -f 3 )
+            mountpoint=$( echo "${line}" | cut -d: -f 3 )
             break
             ;;
         esac
         ;;
       "cpu")
-        case "$controller" in
+        case "${controller}" in
           cpu,cpuacct|cpuacct,cpu|cpuacct|cpu)
-            mountpoint=$( echo "$line" | cut -d: -f 3 )
+            mountpoint=$( echo "${line}" | cut -d: -f 3 )
             break
             ;;
         esac
@@ -122,13 +122,13 @@ __EOF__
 
   case "${found%% *}" in
     "/")
-      foundroot="${found##* }$mountpoint"
+      foundroot="${found##* }${mountpoint}"
       ;;
-    "$mountpoint")
+    "${mountpoint}")
       foundroot="${found##* }"
       ;;
   esac
-  echo "$foundroot"
+  echo "${foundroot}"
 }
 
 get_cgroup_v2_path() {
@@ -140,13 +140,13 @@ get_cgroup_v2_path() {
   [ -r "/proc/self/cgroup" ] || return 1
 
   while IFS= read -r line; do
-    found=$( echo "$line" | cut -d ' ' -f 4,5 )
+    found=$( echo "${line}" | cut -d ' ' -f 4,5 )
   done << __EOF__
 $( grep -F -- '- cgroup2 ' /proc/self/mountinfo )
 __EOF__
 
   while IFS= read -r line; do
-    mountpoint=$( echo "$line" | cut -d: -f 3 )
+    mountpoint=$( echo "${line}" | cut -d: -f 3 )
 done << __EOF__
 $( grep -F -- '0::' /proc/self/cgroup )
 __EOF__
@@ -156,13 +156,13 @@ __EOF__
       return 1
       ;;
     "/")
-      foundroot="${found##* }$mountpoint"
+      foundroot="${found##* }${mountpoint}"
       ;;
-    "$mountpoint" | /../*)
+    "${mountpoint}" | /../*)
       foundroot="${found##* }"
       ;;
   esac
-  echo "$foundroot"
+  echo "${foundroot}"
 }
 
 ncpu_online=$( getconf _NPROCESSORS_ONLN )
@@ -171,18 +171,18 @@ ncpu_quota=
 ncpu_cpuset_v2=
 ncpu_quota_v2=
 
-cpuset=$( get_cgroup_v1_path "cpuset" ) && ncpu_cpuset=$( get_cpuset "$cpuset" "cpuset.effective_cpus" ) || ncpu_cpuset=$ncpu_online
-cpu=$( get_cgroup_v1_path "cpu" ) && ncpu_quota=$( get_quota "$cpu" ) || ncpu_quota=$ncpu_online
-cgroup_v2=$( get_cgroup_v2_path ) && ncpu_cpuset_v2=$( get_cpuset "$cgroup_v2" "cpuset.cpus.effective" ) || ncpu_cpuset_v2=$ncpu_online
-cgroup_v2=$( get_cgroup_v2_path ) && ncpu_quota_v2=$( get_quota_v2 "$cgroup_v2" ) || ncpu_quota_v2=$ncpu_online
+cpuset=$( get_cgroup_v1_path "cpuset" ) && ncpu_cpuset=$( get_cpuset "${cpuset}" "cpuset.effective_cpus" ) || ncpu_cpuset=${ncpu_online}
+cpu=$( get_cgroup_v1_path "cpu" ) && ncpu_quota=$( get_quota "${cpu}" ) || ncpu_quota=${ncpu_online}
+cgroup_v2=$( get_cgroup_v2_path ) && ncpu_cpuset_v2=$( get_cpuset "${cgroup_v2}" "cpuset.cpus.effective" ) || ncpu_cpuset_v2=${ncpu_online}
+cgroup_v2=$( get_cgroup_v2_path ) && ncpu_quota_v2=$( get_quota_v2 "${cgroup_v2}" ) || ncpu_quota_v2=${ncpu_online}
 
 ncpu=$( printf "%s\n%s\n%s\n%s\n%s\n" \
-               "$ncpu_online" \
-               "$ncpu_cpuset" \
-               "$ncpu_quota" \
-               "$ncpu_cpuset_v2" \
-               "$ncpu_quota_v2" \
+               "${ncpu_online}" \
+               "${ncpu_cpuset}" \
+               "${ncpu_quota}" \
+               "${ncpu_cpuset_v2}" \
+               "${ncpu_quota_v2}" \
                | sort -n \
                | head -n 1 )
 
-sed -i.bak -r 's/^(worker_processes)(.*)$/# Commented out by '"$ME"' on '"$(date)"'\n#\1\2\n\1 '"$ncpu"';/' /etc/nginx/nginx.conf
+sed -i.bak -r 's/^(worker_processes)(.*)$/# Commented out by '"${ME}"' on '"$(date)"'\n#\1\2\n\1 '"${ncpu}"';/' /etc/nginx/nginx.conf
diff --git a/stable/debian/docker-entrypoint.sh b/stable/debian/docker-entrypoint.sh
index 8ea04f2..cac74ec 100755
--- a/stable/debian/docker-entrypoint.sh
+++ b/stable/debian/docker-entrypoint.sh
@@ -1,47 +1,47 @@
-#!/bin/sh
+#!/usr/bin/env sh
 # vim:sw=4:ts=4:et
 
 set -e
 
 entrypoint_log() {
     if [ -z "${NGINX_ENTRYPOINT_QUIET_LOGS:-}" ]; then
-        echo "$@"
+        echo "${@}"
     fi
 }
 
-if [ "$1" = "nginx" ] || [ "$1" = "nginx-debug" ]; then
+if [ "${1}" = "nginx" ] || [ "${1}" = "nginx-debug" ]; then
     if /usr/bin/find "/docker-entrypoint.d/" -mindepth 1 -maxdepth 1 -type f -print -quit 2>/dev/null | read v; then
-        entrypoint_log "$0: /docker-entrypoint.d/ is not empty, will attempt to perform configuration"
+        entrypoint_log "${0}: /docker-entrypoint.d/ is not empty, will attempt to perform configuration"
 
-        entrypoint_log "$0: Looking for shell scripts in /docker-entrypoint.d/"
+        entrypoint_log "${0}: Looking for shell scripts in /docker-entrypoint.d/"
         find "/docker-entrypoint.d/" -follow -type f -print | sort -V | while read -r f; do
-            case "$f" in
+            case "${f}" in
                 *.envsh)
-                    if [ -x "$f" ]; then
-                        entrypoint_log "$0: Sourcing $f";
-                        . "$f"
+                    if [ -r "${f}" ]; then
+                        entrypoint_log "${0}: Sourcing ${f}";
+                        . "${f}"
                     else
-                        # warn on shell scripts without exec bit
-                        entrypoint_log "$0: Ignoring $f, not executable";
+                        # warn on shell scripts not readable
+                        entrypoint_log "${0}: Ignoring ${f}, not readable";
                     fi
                     ;;
                 *.sh)
-                    if [ -x "$f" ]; then
-                        entrypoint_log "$0: Launching $f";
-                        "$f"
+                    if [ -x "${f}" ]; then
+                        entrypoint_log "${0}: Launching ${f}";
+                        "${f}"
                     else
                         # warn on shell scripts without exec bit
-                        entrypoint_log "$0: Ignoring $f, not executable";
+                        entrypoint_log "${0}: Ignoring ${f}, not executable";
                     fi
                     ;;
-                *) entrypoint_log "$0: Ignoring $f";;
+                *) entrypoint_log "${0}: Ignoring ${f}";;
             esac
         done
 
-        entrypoint_log "$0: Configuration complete; ready for start up"
+        entrypoint_log "${0}: Configuration complete; ready for start up"
     else
-        entrypoint_log "$0: No files found in /docker-entrypoint.d/, skipping configuration"
+        entrypoint_log "${0}: No files found in /docker-entrypoint.d/, skipping configuration"
     fi
 fi
 
-exec "$@"
+exec "${@}"