diff --git a/.github/scripts/release.sh b/.github/scripts/release.sh
index a09c1e42c..5dc03e557 100755
--- a/.github/scripts/release.sh
+++ b/.github/scripts/release.sh
@@ -17,10 +17,8 @@ if [ $# == 0 ]; then
     exit 1
 elif [ $# == 1 ]; then
     suffix=$1
-    version=$1
 else
     suffix=$1-$2
-    version=$1
 fi
 
 echo "Creating tarball for LibreTime ${suffix}."
@@ -41,9 +39,9 @@ echo " Done"
 #echo "Done"
 
 cd ..
-find libretime-${suffix} -type f -exec dos2unix {} \;
+find "libretime-${suffix}" -type f -exec dos2unix {} \;
 echo -n "Creating tarball..."
-tar -czf libretime-${suffix}.tar.gz \
+tar -czf "libretime-${suffix}.tar.gz" \
         --owner=root --group=root \
         --exclude-vcs \
         --exclude .zfproject.xml \
diff --git a/airtime_mvc/tests/runtests.sh b/airtime_mvc/tests/runtests.sh
index 7213ecadb..ed9ca7624 100755
--- a/airtime_mvc/tests/runtests.sh
+++ b/airtime_mvc/tests/runtests.sh
@@ -30,7 +30,7 @@ export AIRTIME_UNIT_TEST="1"
 
 #Change the working directory to this script's directory
 DIR="$( cd "$( dirname "${BASH_SOURCE[0]}")" && pwd)"
-cd $DIR
+cd "$DIR" || (echo "could not cd in $DIR!" && exit 1)
 
 #Run the unit tests
 phpunit --verbose --log-junit test_results.xml
diff --git a/dev_tools/liquidsoap_compile/liquidsoap-compile.sh b/dev_tools/liquidsoap_compile/liquidsoap-compile.sh
index 211dd7fd3..f59a52e69 100755
--- a/dev_tools/liquidsoap_compile/liquidsoap-compile.sh
+++ b/dev_tools/liquidsoap_compile/liquidsoap-compile.sh
@@ -5,8 +5,8 @@ set -e
 apt-get install -y --force-yes lsb-release sudo
 dist=$(lsb_release -is)
 code=$(lsb_release -cs)
-cpu=$(getconf LONG_BIT)
-cpuvalue=
+# cpu=$(getconf LONG_BIT)
+# cpuvalue=
 
 #enable apt.sourcefabric.org source
 set +e
@@ -32,7 +32,7 @@ if [ "$dist" = "Ubuntu" ]; then
 fi
 
 #enable squeeze backports to get lame packages
-if [ "$dist" = "Debian" -a "$code" = "squeeze" ]; then
+if [[ "$dist" == "Debian" && "$code" == "squeeze" ]]; then
   set +e
   grep -E "deb http://backports.debian.org/debian-backports squeeze-backports main" /etc/apt/sources.list
   returncode=$?
@@ -42,12 +42,12 @@ if [ "$dist" = "Debian" -a "$code" = "squeeze" ]; then
   fi
 fi
 
-echo "System is $cpu bit..."
-if [ "$cpu" = "64" ]; then
-  cpuvalue="amd64"
-else
-  cpuvalue="i386"
-fi
+# echo "System is $cpu bit..."
+# if [ "$cpu" = "64" ]; then
+#   cpuvalue="amd64"
+# else
+#   cpuvalue="i386"
+# fi
 
 apt-get update
 apt-get -o Dpkg::Options::="--force-confold" upgrade
diff --git a/dev_tools/propel_regenerate.sh b/dev_tools/propel_regenerate.sh
index bd2aac7eb..31dfd01c1 100755
--- a/dev_tools/propel_regenerate.sh
+++ b/dev_tools/propel_regenerate.sh
@@ -3,12 +3,12 @@
 set -e
 
 # Absolute path to this script
-SCRIPT=$(readlink -f $0)
+SCRIPT=$(readlink -f "$0")
 # Absolute directory this script is in
-SCRIPTPATH=$(dirname $SCRIPT)
+SCRIPTPATH=$(dirname "$SCRIPT")
 
-cd $SCRIPTPATH/../airtime_mvc/
+cd "$SCRIPTPATH/../airtime_mvc/" || (echo "could not cd in $SCRIPTPATH/../airtime_mvc/" && exit 1)
 path=$(pwd)
 cd build
-sed -i s:"project\.home =.*$":"project.home = $path":g build.properties
+sed -i "s|\"project\.home =.*$\"|\"project.home = $path\"|g" build.properties
 ../../vendor/propel/propel1/generator/bin/propel-gen
diff --git a/dev_tools/release/release.sh b/dev_tools/release/release.sh
index c50f3fa3d..4fac2376a 100755
--- a/dev_tools/release/release.sh
+++ b/dev_tools/release/release.sh
@@ -19,13 +19,13 @@ if [ $# == 0 ]; then
   exit
 elif [ $# == 1 ]; then
   suffix=$1
-  version=$1
+  # version=$1
 else
   suffix=$1-$2
-  version=$1
+  # version=$1
 fi
 
-dir=$(dirname $(readlink -f $0))
+# dir=$(dirname "$(readlink -f "$0")")
 gitrepo=$(readlink -f ./../../)
 
 echo "Creating tarball for LibreTime ${suffix}."
diff --git a/dev_tools/scripts/git-merge-po b/dev_tools/scripts/git-merge-po
index e717fc75d..ac91091bb 100755
--- a/dev_tools/scripts/git-merge-po
+++ b/dev_tools/scripts/git-merge-po
@@ -22,7 +22,8 @@
 #
 # - When merging branches, conflicts in PO files will be marked with "#-#-#-#"
 #
-O=$1
+
+# O=$1
 A=$2
 B=$3
 
diff --git a/dev_tools/update_po_files.sh b/dev_tools/update_po_files.sh
index ee9626aae..ecdb86177 100755
--- a/dev_tools/update_po_files.sh
+++ b/dev_tools/update_po_files.sh
@@ -4,8 +4,8 @@ cd ..
 
 #generate a new .po file
 #this will generate a file called messages.po
-find airtime_mvc -iname "*.phtml" -o -name "*.php" | xargs xgettext -L php --from-code=UTF-8
-find airtime_mvc -iname "*.phtml" -o -name "*.php" | xargs xgettext -L php --from-code=UTF-8 -k --keyword=_pro:1 -d pro --force-po
+find airtime_mvc -print0 -iname "*.phtml" -o -name "*.php" | xargs xgettext -L php --from-code=UTF-8
+find airtime_mvc -print0 -iname "*.phtml" -o -name "*.php" | xargs xgettext -L php --from-code=UTF-8 -k --keyword=_pro:1 -d pro --force-po
 
 #merge the new messages from messages.po into each existing .po file
 #this will generate new .po files
diff --git a/install b/install
index ca90bc661..f7922f9da 100755
--- a/install
+++ b/install
@@ -678,14 +678,14 @@ case "${dist}-${code}" in
     is_debian_buster=true
     ;;
   #Fix for Raspbian 9 (stretch)
-  raspbian-9 | 9)
+  raspbian-9)
     echo -e "ERROR: Raspbian Stretch is archived and does not receive any security or other updates since 2020-06-06." >&2
     echo -e "The LibreTime installer dropped support for installing LibreTime on Stretch in 3.0.0-alpha.10." >&2
     exit 1
     ;;
   #End of fix
   #Fix for Raspbian 10 (buster)
-  raspbian-10 | 10)
+  raspbian-10)
     code="buster"
     dist="debian"
     # shellcheck disable=SC2034
@@ -811,8 +811,8 @@ will be moved to /etc/airtime/airtime.conf.tmp"
       rm -f /etc/apache2/sites-available/airtime.conf /etc/apache2/sites-enabled/airtime.conf
     fi
 
-    if [ -d /usr/share/airtime -a web_root = /usr/share/airtime ]; then
-      rm -rf /usr/share/airtime
+    if [[ -d "/usr/share/airtime" && $web_root == "/usr/share/airtime" ]]; then
+      rm -rf "/usr/share/airtime"
     fi
 
     mv /etc/airtime/airtime.conf /etc/airtime/airtime.conf.tmp
@@ -821,17 +821,17 @@ will be moved to /etc/airtime/airtime.conf.tmp"
 fi
 
 API2_APACHE_CONF=$(grep -F "ProxyPass" /etc/apache2/sites-available/airtime.conf || true)
-if [ -z "${API2_APACHE_CONF}" -a "$apache" = "t" ]; then
+if [[ -z "${API2_APACHE_CONF}" && "$apache" == "t" ]]; then
   # Remove Apache configuration so that the ProxyPass configuration for API 2.0
   # is installed
   rm -f /etc/apache2/sites-available/airtime.conf /etc/apache2/sites-enabled/airtime.conf
 fi
 
-if [ "$apache" = "f" -a ${_i} -eq 1 ]; then
+if [[ "$apache" = "f" && ${_i} -eq 1 ]]; then
   echo -e "Install default Airtime apache configuration? (Y/n): \c"
   read IN
   IN=${IN:-$default_value}
-  if [ "$IN" = "y" -o "$IN" = "Y" ]; then
+  if [[ "$IN" = "y" || "$IN" = "Y" ]]; then
     apache="t"
   fi
 fi
@@ -861,7 +861,7 @@ if [ "$apache" = "t" ]; then
   loud "                * Configuring Apache *                "
   loud "-----------------------------------------------------"
   # Detect Apache root folder, e.g. /etc/apache2 or /etc/httpd
-  eval $($apache_bin -V | awk '/HTTPD_ROOT|SERVER_CONFIG_FILE/ { print $2 }')
+  eval "$($apache_bin -V | awk '/HTTPD_ROOT|SERVER_CONFIG_FILE/ { print $2 }')"
   apache_conf="${HTTPD_ROOT}/${SERVER_CONFIG_FILE}"
   verbose "Detected Apache root folder is: ${HTTPD_ROOT}"
   if [[ ! -e $apache_conf ]]; then
@@ -896,7 +896,7 @@ if [ "$apache" = "t" ]; then
   # install apache, we should overwrite any existing configuration. If we don't do this, doing
   # an in-place installation over an old Airtime install (which installs to /usr/share by default)
   # will fail
-  if [ "$upgrade" = "t" -o ! -f ${apache_sitedir}${airtimeconfigfile} ]; then
+  if [[ "$upgrade" == "t" || ! -f "${apache_sitedir}${airtimeconfigfile}" ]]; then
     verbose "\n * Creating Apache config for Airtime..."
     listen_port=""
     if [ "$web_port" != "80" ]; then
@@ -929,7 +929,7 @@ if [ "$apache" = "t" ]; then
   fi
 fi
 
-if [ "$icecast" = "f" -a ${_i} -eq 1 ]; then
+if [[ "$icecast" == "f" && ${_i} -eq 1 ]]; then
   echo -e "Install default Airtime Icecast configuration? (Y/n): \c"
   read -r IN
   IN=${IN:-$default_value}
@@ -1123,7 +1123,7 @@ EOF
     echo -e "Create default airtime postgres user? (Y/n): \c"
     read IN
     IN=${IN:-$default_value}
-    if [ "$IN" = "y" -o "$IN" = "Y" ]; then
+    if [[ "$IN" = "y" || "$IN" = "Y"  ]]; then
       setupAirtimePostgresUser
     fi
   fi
@@ -1138,7 +1138,7 @@ if [ $skip_rabbitmq -eq 0 ]; then
   RABBITMQ_VHOST=/airtime
   RABBITMQ_USER=airtime
   RABBITMQ_PASSWORD=airtime
-  EXCHANGES="airtime-pypo|pypo-fetch|airtime-analyzer|media-monitor"
+  # EXCHANGES="airtime-pypo|pypo-fetch|airtime-analyzer|media-monitor"
 
   # Ignore errors in this check to avoid dying when vhost isn't found
   set +e
@@ -1197,14 +1197,14 @@ if [ "$ignore_dependencies" = "f" ]; then
   else
     set +e
     verbose "\n * Generating locales"
-    for i in $(ls ${web_root}/../locale | grep ".._.."); do
+    for locale_file in "${web_root}"/../locale/*_*; do
+      locale=$(basename "$locale_file")
       if [ "$dist" = "debian" ]; then
-        grep -qi "^$i" /etc/locale.gen
-        if [ $? -ne 0 ]; then
-          verbose "$i.UTF-8 UTF-8" >> /etc/locale.gen
+        if ! grep -qi "^$locale" /etc/locale.gen; then
+          verbose "$locale.UTF-8 UTF-8" >> /etc/locale.gen
         fi
       else
-        loudCmd "locale-gen \"$i.utf8\""
+        loudCmd "locale-gen \"$locale.utf8\""
       fi
     done
     set -e
diff --git a/python_apps/airtime-celery/install/initd/libretime-celery b/python_apps/airtime-celery/install/initd/libretime-celery
index 5f2969cde..6028a1aeb 100755
--- a/python_apps/airtime-celery/install/initd/libretime-celery
+++ b/python_apps/airtime-celery/install/initd/libretime-celery
@@ -1,4 +1,7 @@
-#!/bin/sh -e
+#!/usr/bin/env bash
+
+set -e
+
 # ============================================
 #  celeryd - Starts the Celery worker daemon.
 # ============================================
@@ -29,7 +32,7 @@
 #
 VERSION=10.1
 echo "celery init v${VERSION}."
-if [ $(id -u) -ne 0 ]; then
+if [ "$(id -u)" -ne 0 ]; then
   echo "Error: This program can only be used by the root user."
   echo "       Unprivileged users must use the 'celery multi' utility, "
   echo "       or 'celery worker --detach'."
@@ -51,15 +54,19 @@ DEFAULT_PID_FILE="/var/run/celery/%n.pid"
 DEFAULT_LOG_FILE="/var/log/celery/%n.log"
 DEFAULT_LOG_LEVEL="INFO"
 DEFAULT_NODES="celery"
-DEFAULT_CELERYD="-m celery worker --detach"
+# DEFAULT_CELERYD="-m celery worker --detach"
 
 CELERY_DEFAULTS=${CELERY_DEFAULTS:-"/etc/default/${SCRIPT_NAME}"}
 # Make sure executable configuration script is owned by root
 _config_sanity() {
-  local path="$1"
-  local owner=$(ls -ld "$path" | awk '{print $3}')
-  local iwgrp=$(ls -ld "$path" | cut -b 6)
-  local iwoth=$(ls -ld "$path" | cut -b 9)
+  local path
+  local owner
+  local iwgrp
+  local iwoth
+  path="$1"
+  owner=$(ls -ld "$path" | awk '{print $3}')
+  iwgrp=$(ls -ld "$path" | cut -b 6)
+  iwoth=$(ls -ld "$path" | cut -b 9)
   if [ "$(id -u $owner)" != "0" ]; then
     echo "Error: Config script '$path' must be owned by root!"
     echo
@@ -97,6 +104,7 @@ _config_sanity() {
 if [ -f "$CELERY_DEFAULTS" ]; then
   _config_sanity "$CELERY_DEFAULTS"
   echo "Using config script: $CELERY_DEFAULTS"
+  # shellcheck disable=SC1090
   . "$CELERY_DEFAULTS"
 fi
 # Sets --app argument for CELERY_BIN
@@ -184,8 +192,10 @@ _get_pids() {
   found_pids=0
   my_exitcode=0
   for pidfile in $(_get_pidfiles); do
-    local pid=$(cat "$pidfile")
-    local cleaned_pid=$(echo "$pid" | sed -e 's/[^0-9]//g')
+    local pid
+    local cleaned_pid
+    pid=$(cat "$pidfile")
+    cleaned_pid=$(echo "$pid" | sed -e 's/[^0-9]//g')
     if [ -z "$pid" ] || [ "$cleaned_pid" != "$pid" ]; then
       echo "bad pid file ($pidfile)"
       one_failed=true
@@ -207,7 +217,7 @@ start_workers() {
   if [ ! -z "$CELERYD_ULIMIT" ]; then
     ulimit $CELERYD_ULIMIT
   fi
-  _chuid $* start $CELERYD_NODES $DAEMON_OPTS \
+  _chuid "$@" start $CELERYD_NODES $DAEMON_OPTS \
     --pidfile="$CELERYD_PID_FILE" \
     --logfile="$CELERYD_LOG_FILE" \
     --loglevel="$CELERYD_LOG_LEVEL" \
@@ -259,9 +269,12 @@ check_status() {
       one_failed=true
       break
     fi
-    local node=$(basename "$pidfile" .pid)
-    local pid=$(cat "$pidfile")
-    local cleaned_pid=$(echo "$pid" | sed -e 's/[^0-9]//g')
+    local node
+    local pid
+    local cleaned_pid
+    node=$(basename "$pidfile" .pid)
+    pid=$(cat "$pidfile")
+    cleaned_pid=$(echo "$pid" | sed -e 's/[^0-9]//g')
     if [ -z "$pid" ] || [ "$cleaned_pid" != "$pid" ]; then
       echo "bad pid file ($pidfile)"
       one_failed=true
diff --git a/python_apps/airtime_analyzer/install/sysvinit/libretime-analyzer b/python_apps/airtime_analyzer/install/sysvinit/libretime-analyzer
index 31da8d5f7..c88be1ea8 100755
--- a/python_apps/airtime_analyzer/install/sysvinit/libretime-analyzer
+++ b/python_apps/airtime_analyzer/install/sysvinit/libretime-analyzer
@@ -20,6 +20,7 @@ PIDFILE=/var/run/$NAME.pid
 [ -x "$DAEMON" ] || exit 0
 
 # Read configuration variable file if it is present
+# shellcheck disable=SC1090
 [ -r /etc/default/$NAME ] && . /etc/default/$NAME
 
 # Load the VERBOSE setting and other rcS variables
diff --git a/python_apps/airtime_analyzer/tools/ftp-upload-hook.sh b/python_apps/airtime_analyzer/tools/ftp-upload-hook.sh
index 90cb85a1e..82b02b118 100755
--- a/python_apps/airtime_analyzer/tools/ftp-upload-hook.sh
+++ b/python_apps/airtime_analyzer/tools/ftp-upload-hook.sh
@@ -17,7 +17,7 @@ post_file() {
   stripped_file_path=${file_path//','/''}
   mv "${file_path}" "${stripped_file_path}"
   file_path="${stripped_file_path}"
-  filename="${file_path##*/}"
+  # filename="${file_path##*/}"
 
   airtime_conf_path=/etc/airtime/airtime.conf
 
diff --git a/python_apps/pypo/install/sysvinit/libretime-liquidsoap b/python_apps/pypo/install/sysvinit/libretime-liquidsoap
index c90142c3a..35b2cd020 100755
--- a/python_apps/pypo/install/sysvinit/libretime-liquidsoap
+++ b/python_apps/pypo/install/sysvinit/libretime-liquidsoap
@@ -20,6 +20,7 @@ PIDFILE=/var/run/$NAME.pid
 [ -x "$DAEMON" ] || exit 0
 
 # Read configuration variable file if it is present
+# shellcheck disable=SC1090
 [ -r /etc/default/$NAME ] && . /etc/default/$NAME
 
 # Load the VERBOSE setting and other rcS variables
diff --git a/python_apps/pypo/install/sysvinit/libretime-playout b/python_apps/pypo/install/sysvinit/libretime-playout
index 7a0b121ed..0183336ac 100755
--- a/python_apps/pypo/install/sysvinit/libretime-playout
+++ b/python_apps/pypo/install/sysvinit/libretime-playout
@@ -20,6 +20,7 @@ PIDFILE=/var/run/$NAME.pid
 [ -x "$DAEMON" ] || exit 0
 
 # Read configuration variable file if it is present
+# shellcheck disable=SC1090
 [ -r /etc/default/$NAME ] && . /etc/default/$NAME
 
 # Load the VERBOSE setting and other rcS variables
diff --git a/utils/airtime-test-soundcard b/utils/airtime-test-soundcard
index 67722cdf2..f852267a7 100755
--- a/utils/airtime-test-soundcard
+++ b/utils/airtime-test-soundcard
@@ -28,6 +28,6 @@ SCRIPT=$(readlink -f $0)
 # Absolute directory this script is in
 SCRIPTPATH=$(dirname $SCRIPT)
 
-cd $SCRIPTPATH
+cd $SCRIPTPATH || exit 1
 
 python airtime-test-soundcard.py "$@" || exit 1
diff --git a/utils/airtime-test-stream b/utils/airtime-test-stream
index 8634b2dc2..1ebc328dc 100755
--- a/utils/airtime-test-stream
+++ b/utils/airtime-test-stream
@@ -28,6 +28,6 @@ SCRIPT=$(readlink -f $0)
 # Absolute directory this script is in
 SCRIPTPATH=$(dirname $SCRIPT)
 
-cd $SCRIPTPATH
+cd $SCRIPTPATH || exit 1
 
 python airtime-test-stream.py "$@" || exit 1
diff --git a/utils/libretime-backup.sh b/utils/libretime-backup.sh
index 03f7602c1..529cc64dd 100755
--- a/utils/libretime-backup.sh
+++ b/utils/libretime-backup.sh
@@ -11,34 +11,34 @@ fi
 airtime_conf_path=/etc/airtime/airtime.conf
 uploads_folder=/srv/airtime/stor/
 
-psdl_db=$(grep dbname ${airtime_conf_path} | awk '{print $3;}')
+psql_db=$(grep dbname ${airtime_conf_path} | awk '{print $3;}')
 psql_user=$(grep dbuser ${airtime_conf_path} | awk '{print $3;}')
 psql_password=$(grep dbpass ${airtime_conf_path} | awk '{print $3;}')
 
 ## Remove old backup
-rm -rf $backup_folder
-mkdir $backup_folder
+rm -rf "$backup_folder"
+mkdir "$backup_folder"
 
 ## Backup of database
 
-echo 'db: Getting database...'
-pg_dump --dbname='postgresql://'$psql_user':'$psql_password'@localhost/'$psql_db > $backup_folder'database'
-echo 'db: Complete'
+echo "db: Getting database..."
+pg_dump --dbname="postgresql://$psql_user:$psql_password@localhost/$psql_db" > "${backup_folder}database"
+echo "db: Complete"
 
 ## Backup of sounds
 
-mkdir $backup_folder'uploads/'
+mkdir "${backup_folder}uploads/"
 
-echo 'stor : Copying uploaded files...'
-rsync -r -a --info=progress2 $uploads_folder $backup_folder'uploads/'
-echo 'stor: Complete'
+echo "stor : Copying uploaded files..."
+rsync -r -a --info=progress2 $uploads_folder "${backup_folder}uploads/"
+echo "stor: Complete"
 
 ## Backup of libretime config
 
-mkdir $backup_folder'airtime_config/'
+mkdir "${backup_folder}airtime_config/"
 
-echo 'config: Copying config...'
-rsync -r -a --info=progress2 /etc/airtime/ $backup_folder'airtime_config/'
-echo 'config: Complete'
+echo "config: Copying config..."
+rsync -r -a --info=progress2 /etc/airtime/ "${backup_folder}airtime_config/"
+echo "config: Complete"
 
-date >> $backup_folder'datelog.txt'
+date >> "${backup_folder}datelog.txt"
diff --git a/utils/rivendell-converter.sh b/utils/rivendell-converter.sh
index a16b26c2d..38f3d071d 100755
--- a/utils/rivendell-converter.sh
+++ b/utils/rivendell-converter.sh
@@ -21,17 +21,17 @@ db="Rivendell" #Edit this only if you changed Rivendell's database name :-)
 rivendell_dir=$1
 end_dir=$2
 
-cd "$rivendell_dir"
+cd "$rivendell_dir" || (echo "could not cd in $rivendell_dir" && exit 1)
 
 for file in *; do
   lame "$file"
 done
 
 mv "$rivendell_dir"/*.mp3 "$end_dir"
-cd "$end_dir"
+cd "$end_dir" || (echo "could not cd in $end_dir" && exit 1)
 
 for file in *; do
-  id=$(echo $file | head -c 10)
+  id=$(echo "$file" | head -c 10)
   title=$(mysql -u $user -p$pass -sN -e "SELECT CU.DESCRIPTION FROM CUTS CU, CART CA WHERE CA.NUMBER=CU.CART_NUMBER AND CU.CUT_NAME=\"${id}\"" $db)
   artist=$(mysql -u $user -p$pass -sN -e "SELECT CA.ARTIST FROM CUTS CU, CART CA WHERE CA.NUMBER=CU.CART_NUMBER AND CU.CUT_NAME=\"${id}\"" $db)
   album=$(mysql -u $user -p$pass -sN -e "SELECT CA.ALBUM FROM CUTS CU, CART CA WHERE CA.NUMBER=CU.CART_NUMBER AND CU.CUT_NAME=\"${id}\"" $db)