diff --git a/contrib/dokku_client.sh b/contrib/dokku_client.sh
index 2e2f6ae78..85c1c1480 100755
--- a/contrib/dokku_client.sh
+++ b/contrib/dokku_client.sh
@@ -125,7 +125,7 @@ main() {
       else
         APP="$APP_ARG"
       fi
-      if git remote add $DOKKU_GIT_REMOTE "dokku@$DOKKU_REMOTE_HOST:$APP"; then
+      if git remote add "$DOKKU_GIT_REMOTE" "dokku@$DOKKU_REMOTE_HOST:$APP"; then
         echo "-----> Dokku remote added at ${DOKKU_REMOTE_HOST} called ${DOKKU_GIT_REMOTE}"
         echo "-----> Application name is ${APP}"
       else
diff --git a/plugins/20_events/install b/plugins/20_events/install
index e6991005f..cdc5cb497 100755
--- a/plugins/20_events/install
+++ b/plugins/20_events/install
@@ -10,6 +10,7 @@ flag_rsyslog_needs_restart=n
 
 # This can be done unconditionally as mkdir -p
 # exits gracefully if the path already exists
+# shellcheck disable=SC2174
 mkdir -m 775 -p "$DOKKU_LOGS_DIR"
 case "$DOKKU_DISTRO" in
   arch|debian|centos)
diff --git a/plugins/checks/check-deploy b/plugins/checks/check-deploy
index 7652331e4..7afe7a56b 100755
--- a/plugins/checks/check-deploy
+++ b/plugins/checks/check-deploy
@@ -74,7 +74,7 @@ checks_check_deploy() {
   # after successfully copying the file. Thus, we suppress stderr.
   # ref: https://github.com/dotcloud/docker/issues/3986
   local CHECK_DEPLOY_TMP_WORK_DIR=$(mktemp -d /tmp/dokku_CHECKS.XXXXX)
-  docker cp $DOKKU_APP_CONTAINER_ID:/app/CHECKS "$CHECK_DEPLOY_TMP_WORK_DIR" 2> /dev/null || true
+  docker cp "$DOKKU_APP_CONTAINER_ID:/app/CHECKS" "$CHECK_DEPLOY_TMP_WORK_DIR" 2> /dev/null || true
 
   local FILENAME=${CHECK_DEPLOY_TMP_WORK_DIR}/CHECKS
 
@@ -107,8 +107,8 @@ checks_check_deploy() {
     dokku_log_info1 "Waiting for $DOKKU_DEFAULT_CHECKS_WAIT seconds ..."
     sleep "$DOKKU_DEFAULT_CHECKS_WAIT"
 
-    ! (is_container_running $DOKKU_APP_CONTAINER_ID) && dokku_log_fail "App container failed to start!!"
-    local container_restarts=$(docker inspect -f "{{ .RestartCount }}" $DOKKU_APP_CONTAINER_ID)
+    ! (is_container_running "$DOKKU_APP_CONTAINER_ID") && dokku_log_fail "App container failed to start!!"
+    local container_restarts="$(docker inspect -f "{{ .RestartCount }}" "$DOKKU_APP_CONTAINER_ID")"
     if [[ $container_restarts -ne 0 ]]; then
       docker stop "$DOKKU_APP_CONTAINER_ID" || true
       dokku_log_fail "App container failed to start!!"
diff --git a/plugins/common/functions b/plugins/common/functions
index e2843bf69..543c454a8 100755
--- a/plugins/common/functions
+++ b/plugins/common/functions
@@ -142,7 +142,7 @@ verify_app_name() {
   local APP="$1"
   [[ ! -n "$APP" ]] && dokku_log_fail "(verify_app_name) APP must not be null"
   if [[ ! "$APP" =~ ^[a-z].* && ! "$APP" =~ ^[0-9].* ]]; then
-    [[ -d "$DOKKU_ROOT/$APP" ]] && rm -rf "$DOKKU_ROOT/$APP"
+    [[ -d "$DOKKU_ROOT/$APP" ]] && rm -rf "${DOKKU_ROOT:?}/$APP"
     dokku_log_fail "App name must begin with lowercase alphanumeric character"
   fi
   [[ ! -d "$DOKKU_ROOT/$APP" ]] && dokku_log_fail "App $APP does not exist"
@@ -211,7 +211,7 @@ get_running_image_tag() {
   verify_app_name "$APP"
 
   local CIDS=( $(get_app_container_ids "$APP") )
-  local RUNNING_IMAGE_TAG=$(docker inspect -f '{{ .Config.Image }}' ${CIDS[0]} 2>/dev/null | awk -F: '{ print $2 }' || echo '')
+  local RUNNING_IMAGE_TAG=$(docker inspect -f '{{ .Config.Image }}' "${CIDS[0]}" 2>/dev/null | awk -F: '{ print $2 }' || echo '')
   echo "$RUNNING_IMAGE_TAG"
 }
 
@@ -331,10 +331,11 @@ get_app_container_ids() {
 get_app_running_container_ids() {
   declare desc="return list of running docker container ids for given app and optional container_type"
   local APP="$1" CONTAINER_TYPE="$2"
+  local CIDS
   verify_app_name "$APP"
 
   ! (is_deployed "$APP") && dokku_log_fail "App $APP has not been deployed"
-  local CIDS=$(get_app_container_ids "$APP" "$CONTAINER_TYPE")
+  CIDS=$(get_app_container_ids "$APP" "$CONTAINER_TYPE")
 
   for CID in $CIDS; do
     local APP_CONTAINER_STATUS=$(docker inspect -f '{{.State.Running}}' "$CID" 2>/dev/null || true)
@@ -367,7 +368,7 @@ get_cmd_from_procfile() {
 
   if [[ -f $DOKKU_PROCFILE ]]; then
     local line; local name; local command
-    while read line || [[ -n "$line" ]]; do
+    while read -r line || [[ -n "$line" ]]; do
       if [[ -z "$line" ]] || [[ "$line" == "#"* ]]; then
         continue
       fi
@@ -702,6 +703,8 @@ release_and_deploy() {
   source "$PLUGIN_AVAILABLE_PATH/config/functions"
 
   local APP="$1"; local IMAGE_TAG="$2"; local IMAGE=$(get_app_image_name "$APP" "$IMAGE_TAG")
+  local DOKKU_DOCKERFILE_PORTS
+
   verify_app_name "$APP"
 
   if verify_image "$IMAGE"; then
@@ -709,7 +712,7 @@ release_and_deploy() {
       local IMAGE_SOURCE_TYPE="herokuish"
     else
       local IMAGE_SOURCE_TYPE="dockerfile"
-      local DOKKU_DOCKERFILE_PORTS=$(config_get "$APP" DOKKU_DOCKERFILE_PORTS || true)
+      DOKKU_DOCKERFILE_PORTS=$(config_get "$APP" DOKKU_DOCKERFILE_PORTS || true)
       if [[ -z "$DOKKU_DOCKERFILE_PORTS" ]]; then
         local DOCKER_IMAGE_PORTS=$(get_exposed_ports_from_image "$IMAGE")
         [[ -n "$DOCKER_IMAGE_PORTS" ]] && config_set --no-restart "$APP" DOKKU_DOCKERFILE_PORTS="$DOCKER_IMAGE_PORTS"
diff --git a/plugins/docker-options/subcommands/remove b/plugins/docker-options/subcommands/remove
index 6a0b651bf..8677039ed 100755
--- a/plugins/docker-options/subcommands/remove
+++ b/plugins/docker-options/subcommands/remove
@@ -10,6 +10,7 @@ docker_options_remove_cmd() {
   verify_app_name "$2" && local APP="$2"
   read -ra passed_phases <<< "$(get_phases "$3")"
   shift 3 # everything else passed is the docker option
+  # shellcheck disable=SC2154
   [[ -z ${passed_docker_option="$@"} ]] && dokku_log_fail "Please specify docker options to add to the phase"
   remove_passed_docker_option passed_phases[@] "${passed_docker_option[@]}"
 }
diff --git a/plugins/enter/subcommands/default b/plugins/enter/subcommands/default
index 9d2a23da1..b53ea0a71 100755
--- a/plugins/enter/subcommands/default
+++ b/plugins/enter/subcommands/default
@@ -12,7 +12,7 @@ enter_default_cmd() {
   if [[ -z "$3" ]]; then
     if [[ ${#AVAILABLE_CONTAINER_TYPES[@]} -gt 1 ]]; then
       dokku_log_warn "No container type specified."
-      dokku_log_fail "Available types for app ($APP): ${AVAILABLE_CONTAINER_TYPES[@]}"
+      dokku_log_fail "Available types for app ($APP): ${AVAILABLE_CONTAINER_TYPES[*]}"
     else
       CONTAINER_TYPE="${AVAILABLE_CONTAINER_TYPES[0]}"
     fi
@@ -22,11 +22,11 @@ enter_default_cmd() {
     local DOKKU_APP_CIDS=( $(get_app_container_ids "$APP") )
     if [[ ! -n "$4" ]]; then
       dokku_log_warn "No container id specified."
-      dokku_log_fail "Available ids for app ($APP): ${DOKKU_APP_CIDS[@]}"
+      dokku_log_fail "Available ids for app ($APP): ${DOKKU_APP_CIDS[*]}"
     fi
     if ! (printf -- '%s\n' "${DOKKU_APP_CIDS[@]}" | grep -q -e "^$4"); then
       dokku_log_warn "Invalid container id for app"
-      dokku_log_fail "Available ids for app ($APP): ${DOKKU_APP_CIDS[@]}"
+      dokku_log_fail "Available ids for app ($APP): ${DOKKU_APP_CIDS[*]}"
     fi
     local ID=$(printf -- '%s\n' "${DOKKU_APP_CIDS[@]}" | grep -e "^$4")
     shift 4
@@ -35,7 +35,7 @@ enter_default_cmd() {
     local ID=${DOKKU_APP_CIDS[0]}
     if [[ ! -n $ID ]]; then
       dokku_log_warn "No containers found for type '$CONTAINER_TYPE'"
-      dokku_log_fail "Available types for app ($APP): ${AVAILABLE_CONTAINER_TYPES[@]}"
+      dokku_log_fail "Available types for app ($APP): ${AVAILABLE_CONTAINER_TYPES[*]}"
     fi
     if [[ $3 ]]; then
       shift 3
diff --git a/plugins/git/functions b/plugins/git/functions
index 4c6a4a62c..ceebfb5b1 100755
--- a/plugins/git/functions
+++ b/plugins/git/functions
@@ -30,7 +30,7 @@ git_build_app_repo() {
   git reset --hard FETCH_HEAD &> /dev/null
   suppress_output git submodule update --init --recursive
   GIT_DIR="$DOKKU_ROOT/$APP" git tag -d "$TMP_TAG" &> /dev/null || true
-  find -name .git -prune -exec rm -rf {} \; > /dev/null
+  find . -name .git -prune -exec rm -rf {} \; > /dev/null
 
   plugn trigger post-extract "$APP" "$GIT_BUILD_APP_REPO_TMP_WORK_DIR" "$REV"
 
diff --git a/plugins/logs/subcommands/default b/plugins/logs/subcommands/default
index e97480c6a..14532f31d 100755
--- a/plugins/logs/subcommands/default
+++ b/plugins/logs/subcommands/default
@@ -17,7 +17,8 @@ logs_default_cmd() {
 
   shift 2;
   local TEMP=$(getopt -o htqn:p: --long help,tail,quiet,num:,ps: -n 'dokku logs' -- "$@")
-  if [[ $? != 0 ]]; then usage >&2 ; exit 1 ; fi
+  local EXIT_CODE="$?"
+  if [[ "$EXIT_CODE" != 0 ]]; then usage >&2 ; exit 1 ; fi
   eval set -- "$TEMP"
 
   local DOKKU_LOGS_LINE_NUMBERS="100"
diff --git a/plugins/ps/functions b/plugins/ps/functions
index 3191f88ef..f9f094df8 100755
--- a/plugins/ps/functions
+++ b/plugins/ps/functions
@@ -77,9 +77,9 @@ set_scale() {
   for procscale in "${SCALE_SETTINGS[@]}"; do
     local PROC_NAME=${procscale%%=*}
     local PROC_COUNT=${procscale#*=}
-    is_number $PROC_COUNT || dokku_log_fail "ps:scale $PROC_COUNT is not a number"
+    is_number "$PROC_COUNT" || dokku_log_fail "ps:scale $PROC_COUNT is not a number"
     dokku_log_info1_quiet "Scaling $APP:$PROC_NAME to $PROC_COUNT"
-    if (egrep -q ^${PROC_NAME}= "$DOKKU_SCALE_FILE" > /dev/null 2>&1); then
+    if (egrep -q "^${PROC_NAME}=" "$DOKKU_SCALE_FILE" > /dev/null 2>&1); then
       sed --in-place "s:^${PROC_NAME}=.*:$PROC_NAME=$PROC_COUNT:g" "$DOKKU_SCALE_FILE"
     else
       echo "$PROC_NAME=$PROC_COUNT" >> "$DOKKU_SCALE_FILE"
diff --git a/plugins/ssh-keys/functions b/plugins/ssh-keys/functions
index f45dce1ff..2d5d1ebf0 100755
--- a/plugins/ssh-keys/functions
+++ b/plugins/ssh-keys/functions
@@ -13,7 +13,7 @@ verify_ssh_key_file() {
   declare desc="Test that public key is valid"
   [[ -s ${DOKKU_ROOT}/.ssh/authorized_keys ]] || dokku_log_fail "No public keys found."
   local key line=0
-  while read key ; do
+  while read -r key; do
     line=$((line + 1))
     ssh-keygen -l -f /dev/stdin <<< "$key" &> /dev/null || dokku_log_fail "${DOKKU_ROOT}/.ssh/authorized_keys line $line failed ssh-keygen check."
   done <"${DOKKU_ROOT}/.ssh/authorized_keys"