diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 03b75882..f42c096b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,7 +11,7 @@ jobs:
   bats-test:
     strategy:
       matrix:
-        os: [ubuntu-20.04, ubuntu-18.04, ubuntu-16.04, macos-10.15, macos-11.0]
+        os: [ubuntu-20.04, ubuntu-18.04, macos-10.15, macos-11.0]
 
     runs-on: ${{ matrix.os }}
 
diff --git a/.shellcheckrc b/.shellcheckrc
deleted file mode 100644
index 6418bd8f..00000000
--- a/.shellcheckrc
+++ /dev/null
@@ -1,6 +0,0 @@
-# We use colors and not assigned
-disable=SC2154
-# Hard to fix
-disable=SC2155
-# shellcheck is wrong on some
-disable=SC2034
diff --git a/bash_it.sh b/bash_it.sh
index b8d3aeef..679ffdaf 100755
--- a/bash_it.sh
+++ b/bash_it.sh
@@ -114,6 +114,7 @@ for _bash_it_config_file in $CUSTOM; do
 	if [ -e "${_bash_it_config_file}" ]; then
 		filename=$(basename "${_bash_it_config_file}")
 		filename=${filename%*.bash}
+		# shellcheck disable=SC2034
 		BASH_IT_LOG_PREFIX="custom: $filename: "
 		_log_debug "Loading custom file..."
 		# shellcheck disable=SC1090
@@ -122,7 +123,7 @@ for _bash_it_config_file in $CUSTOM; do
 done
 
 unset _bash_it_config_file
-if [[ "${PROMPT:-}" ]]; then
+if [[ -n "${PROMPT:-}" ]]; then
 	export PS1="\[""$PROMPT""\]"
 fi
 
diff --git a/completion/available/composer.completion.bash b/completion/available/composer.completion.bash
index eefe50fa..176f0832 100644
--- a/completion/available/composer.completion.bash
+++ b/completion/available/composer.completion.bash
@@ -3,14 +3,14 @@ cite "about-completion"
 about-completion "composer completion"
 
 function __composer_completion() {
-	local cur coms opts com
+	local cur coms opts com words
 	COMPREPLY=()
 	_get_comp_words_by_ref -n : cur words
 
 	# lookup for command
 	for word in "${words[@]:1}"; do
-		if [[ $word != -* ]]; then
-			com=$word
+		if [[ "${word}" != -* ]]; then
+			com="${word}"
 			break
 		fi
 	done
@@ -19,7 +19,7 @@ function __composer_completion() {
 	if [[ ${cur} == --* ]]; then
 		opts="--help --quiet --verbose --version --ansi --no-ansi --no-interaction --profile --no-plugins --working-dir"
 
-		case "$com" in
+		case "${com}" in
 			about)
 				opts="${opts} "
 				;;
@@ -109,18 +109,18 @@ function __composer_completion() {
 
 		# shellcheck disable=SC2207
 		COMPREPLY=($(compgen -W "${opts}" -- "${cur}"))
-		__ltrim_colon_completions "$cur"
+		__ltrim_colon_completions "${cur}"
 
 		return 0
 	fi
 
 	# completing for a command
-	if [[ "$cur" == "$com" ]]; then
+	if [[ "${cur}" == "${com}" ]]; then
 		coms="about archive browse clear-cache config create-project depends diagnose dump-autoload exec global help init install licenses list outdated prohibits remove require run-script search self-update show status suggests update validate"
 
 		# shellcheck disable=SC2207
 		COMPREPLY=($(compgen -W "${coms}" -- "${cur}"))
-		__ltrim_colon_completions "$cur"
+		__ltrim_colon_completions "${cur}"
 
 		return 0
 	fi
diff --git a/completion/available/dart.completion.bash b/completion/available/dart.completion.bash
index ece96d5c..b7563443 100644
--- a/completion/available/dart.completion.bash
+++ b/completion/available/dart.completion.bash
@@ -1,7 +1,9 @@
 # shellcheck shell=bash
 
 __dart_completion() {
+	# shellcheck disable=SC2155
 	local prev=$(_get_pword)
+	# shellcheck disable=SC2155
 	local curr=$(_get_cword)
 
 	local HELP="--help -h"
diff --git a/completion/available/dmidecode.completion.bash b/completion/available/dmidecode.completion.bash
index fc50c1f0..4a884524 100644
--- a/completion/available/dmidecode.completion.bash
+++ b/completion/available/dmidecode.completion.bash
@@ -1,7 +1,9 @@
 # shellcheck shell=bash
 
 function __dmidecode_completion() {
+	# shellcheck disable=SC2155
 	local prev=$(_get_pword)
+	# shellcheck disable=SC2155
 	local curr=$(_get_cword)
 
 	case $prev in
diff --git a/completion/available/knife.completion.bash b/completion/available/knife.completion.bash
index 83b332f9..4b9950ed 100644
--- a/completion/available/knife.completion.bash
+++ b/completion/available/knife.completion.bash
@@ -42,6 +42,7 @@ _KAC_is_file_newer_than() {
 _KAC_regen_cache() {
 	local CACHE_NAME=$1
 	local CACHE_PATH="$_KNIFE_AUTOCOMPLETE_CACHE_DIR/$CACHE_NAME"
+	# shellcheck disable=SC2155
 	local TMP_FILE=$(mktemp "$_KAC_CACHE_TMP_DIR/$CACHE_NAME.XXXX")
 	shift 1
 	# discard the temp file if it's empty AND the previous command didn't exit successfully, but still mark the cache as updated
@@ -66,6 +67,7 @@ _KAC_get_command_from_cache_name() {
 # otherwise it waits for the cache to be generated
 # in either case, it regenerates the cache, and sets the _KAC_CACHE_PATH env variable
 # for obvious reason, do NOT call that in a sub-shell (in particular, no piping)
+# shellcheck disable=SC2155
 _KAC_get_and_regen_cache() {
 	# the cache name can't have space in it
 	local CACHE_NAME=$(_KAC_get_cache_name_from_command "$@")
@@ -100,7 +102,7 @@ _KAC_clean_cache() {
 
 # perform a cache cleaning when loading this file
 # On big systems this could baloon up to a 30 second run or more, so not enabling by default.
-[[ "${KNIFE_CACHE_CLEAN}" ]] && _KAC_clean_cache
+[[ -n "${KNIFE_CACHE_CLEAN}" ]] && _KAC_clean_cache
 
 #####################################
 ### End of cache helper functions ###
@@ -118,7 +120,7 @@ _KAC_get_current_base_command() {
 	local PREVIOUS="knife"
 	local I=1
 	local CURRENT
-	while [ $I -le "$COMP_CWORD" ]; do
+	while [[ "${I}" -le "${COMP_CWORD}" ]]; do
 		# command words are all lower-case
 		echo "${COMP_WORDS[$I]}" | grep -E "^[a-z]+$" > /dev/null || break
 		CURRENT="$PREVIOUS ${COMP_WORDS[$I]}"
@@ -127,12 +129,13 @@ _KAC_get_current_base_command() {
 		I=$((I + 1))
 	done
 	_KAC_CURRENT_COMMAND=$PREVIOUS
-	[ $I -le "$COMP_CWORD" ] && _KAC_CURRENT_COMMAND_NB_WORDS=$I
+	[[ "${I}" -le "${COMP_CWORD}" ]] && _KAC_CURRENT_COMMAND_NB_WORDS="${I}"
 }
 
 # searches the position of the currently completed argument in the current base command
 # (i.e. handles "plural" arguments such as knife cookbook upload cookbook1 cookbook2 and so on...)
 # assumes the current base command is complete
+# shellcheck disable=SC2155
 _KAC_get_current_arg_position() {
 	local CURRENT_ARG_POS=$((_KAC_CURRENT_COMMAND_NB_WORDS + 1))
 	local COMPLETE_COMMAND=$(grep -E "^$_KAC_CURRENT_COMMAND" "$_KAC_CACHE_PATH")
@@ -150,10 +153,11 @@ _KAC_get_current_arg_position() {
 _knife() {
 	_KAC_get_and_regen_cache _KAC_knife_commands
 	local RAW_LIST ITEM REGEN_CMD ARG_POSITION
+	# shellcheck disable=SC2034
 	COMREPLY=()
 	# get correct command & arg pos
 	_KAC_get_current_base_command && ARG_POSITION=$(_KAC_get_current_arg_position) || ARG_POSITION=$((COMP_CWORD + 1))
-	RAW_LIST=$(grep -E "^$_KAC_CURRENT_COMMAND" "$_KAC_CACHE_PATH" | cut -d ' ' -f $ARG_POSITION | uniq)
+	RAW_LIST=$(grep -E "^${_KAC_CURRENT_COMMAND}" "${_KAC_CACHE_PATH}" | cut -d ' ' -f "${ARG_POSITION}" | uniq)
 
 	# we need to process that raw list a bit, most notably for placeholders
 	# NOTE: I chose to explicitely fetch & cache _certain_ informations for the server (cookbooks & node names, etc)
diff --git a/completion/available/ngrok.completion.bash b/completion/available/ngrok.completion.bash
index ffbdd3c8..ca50a16f 100644
--- a/completion/available/ngrok.completion.bash
+++ b/completion/available/ngrok.completion.bash
@@ -1,7 +1,9 @@
 # shellcheck shell=bash
 
 __ngrok_completion() {
+	# shellcheck disable=SC2155
 	local prev=$(_get_pword)
+	# shellcheck disable=SC2155
 	local curr=$(_get_cword)
 
 	local BASE_NO_CONF="--log --log-format --log-level --help"
diff --git a/completion/available/notify-send.completion.bash b/completion/available/notify-send.completion.bash
index b2c171e9..676485f8 100644
--- a/completion/available/notify-send.completion.bash
+++ b/completion/available/notify-send.completion.bash
@@ -1,7 +1,9 @@
 # shellcheck shell=bash
 
 function __notify-send_completions() {
+	# shellcheck disable=SC2155
 	local curr=$(_get_cword)
+	# shellcheck disable=SC2155
 	local prev=$(_get_pword)
 
 	case $prev in
diff --git a/completion/available/sdkman.completion.bash b/completion/available/sdkman.completion.bash
index 7f0157f3..2dc09088 100644
--- a/completion/available/sdkman.completion.bash
+++ b/completion/available/sdkman.completion.bash
@@ -1,7 +1,9 @@
 # shellcheck shell=bash
-_sdkman_complete() {
+
+function _sdkman_complete() {
 	local CANDIDATES
 	local CANDIDATE_VERSIONS
+	local SDKMAN_CANDIDATES_CSV="${SDKMAN_CANDIDATES_CSV:-}"
 
 	COMPREPLY=()
 
@@ -10,7 +12,7 @@ _sdkman_complete() {
 	elif [ "$COMP_CWORD" -eq 2 ]; then
 		case "${COMP_WORDS[COMP_CWORD - 1]}" in
 			"install" | "i" | "uninstall" | "rm" | "list" | "ls" | "use" | "u" | "default" | "d" | "home" | "h" | "current" | "c" | "upgrade" | "ug")
-				CANDIDATES=$(echo "${SDKMAN_CANDIDATES_CSV}" | tr ',' ' ')
+				CANDIDATES="${SDKMAN_CANDIDATES_CSV//,/${IFS:0:1}}"
 				mapfile -t COMPREPLY < <(compgen -W "$CANDIDATES" -- "${COMP_WORDS[COMP_CWORD]}")
 				;;
 			"env")
@@ -46,17 +48,17 @@ _sdkman_complete() {
 	return 0
 }
 
-_sdkman_candidate_local_versions() {
+function _sdkman_candidate_local_versions() {
 
 	CANDIDATE_VERSIONS=$(__sdkman_cleanup_local_versions "$1")
 
 }
 
-_sdkman_candidate_all_versions() {
+function _sdkman_candidate_all_versions() {
 
 	candidate="$1"
 	CANDIDATE_LOCAL_VERSIONS=$(__sdkman_cleanup_local_versions "$candidate")
-	if [ "$SDKMAN_OFFLINE_MODE" = "true" ]; then
+	if [[ "${SDKMAN_OFFLINE_MODE:-false}" == "true" ]]; then
 		CANDIDATE_VERSIONS=$CANDIDATE_LOCAL_VERSIONS
 	else
 		# sdkman has a specific output format for Java candidate since
@@ -70,12 +72,12 @@ _sdkman_candidate_all_versions() {
 		# "+" - local version
 		# "*" - installed
 		# ">" - currently in use
-		CANDIDATE_VERSIONS="$(echo "$CANDIDATE_ONLINE_VERSIONS $CANDIDATE_LOCAL_VERSIONS" | tr ' ' '\n' | grep -v -e '^[[:space:]|\*|\>|\+]*$' | sort | uniq -u) "
+		CANDIDATE_VERSIONS="$(echo "$CANDIDATE_ONLINE_VERSIONS $CANDIDATE_LOCAL_VERSIONS" | tr ' ' '\n' | grep -v -e '^[[:space:]|\*|\>|\+]*$' | sort -u) "
 	fi
 
 }
 
-__sdkman_cleanup_local_versions() {
+function __sdkman_cleanup_local_versions() {
 
 	__sdkman_build_version_csv "$1" | tr ',' ' '
 
diff --git a/completion/available/vuejs.completion.bash b/completion/available/vuejs.completion.bash
index bbd79b9c..751658f0 100644
--- a/completion/available/vuejs.completion.bash
+++ b/completion/available/vuejs.completion.bash
@@ -1,7 +1,9 @@
 # shellcheck shell=bash
 
 __vuejs_completion() {
+	# shellcheck disable=SC2155
 	local prev=$(_get_pword)
+	# shellcheck disable=SC2155
 	local curr=$(_get_cword)
 
 	case $prev in
diff --git a/hooks/dot-bash.sh b/hooks/dot-bash.sh
index 7a9dc8bc..253cb595 100755
--- a/hooks/dot-bash.sh
+++ b/hooks/dot-bash.sh
@@ -18,4 +18,4 @@ for file in "$@"; do
 	fi
 done
 
-exit $exit_code
+exit "${exit_code:-0}"
diff --git a/hooks/dot-sh.sh b/hooks/dot-sh.sh
index 3fa63216..e1086bb6 100755
--- a/hooks/dot-sh.sh
+++ b/hooks/dot-sh.sh
@@ -18,4 +18,4 @@ for file in "$@"; do
 	fi
 done
 
-exit $exit_code
+exit "${exit_code:-0}"
diff --git a/install.sh b/install.sh
index 4940360f..45c975fd 100755
--- a/install.sh
+++ b/install.sh
@@ -83,8 +83,8 @@ function _bash-it_check_for_backup() {
 	fi
 	echo -e "\033[0;33mBackup file already exists. Make sure to backup your .bashrc before running this installation.\033[0m" >&2
 
-	if ! [[ $overwrite_backup ]]; then
-		while ! [[ $silent ]]; do
+	if [[ -z "${overwrite_backup}" ]]; then
+		while [[ -z "${silent}" ]]; do
 			read -e -n 1 -r -p "Would you like to overwrite the existing backup? This will delete your existing backup file ($HOME/$BACKUP_FILE) [y/N] " RESP
 			case $RESP in
 				[yY])
@@ -100,9 +100,9 @@ function _bash-it_check_for_backup() {
 			esac
 		done
 	fi
-	if ! [[ $overwrite_backup ]]; then
+	if [[ -z "${overwrite_backup}" ]]; then
 		echo -e "\033[91mInstallation aborted. Please come back soon!\033[m"
-		if [[ $silent ]]; then
+		if [[ -n "${silent}" ]]; then
 			echo -e "\033[91mUse \"-f\" flag to force overwrite of backup.\033[m"
 		fi
 		exit 1
@@ -114,8 +114,8 @@ function _bash-it_check_for_backup() {
 function _bash-it_modify_config_files() {
 	_bash-it_check_for_backup
 
-	if ! [[ $silent ]]; then
-		while ! [[ $append_to_config ]]; do
+	if [[ -z "${silent}" ]]; then
+		while [[ -z "${append_to_config}" ]]; do
 			read -e -n 1 -r -p "Would you like to keep your $CONFIG_FILE and append bash-it templates at the end? [y/N] " choice
 			case $choice in
 				[yY])
@@ -131,7 +131,7 @@ function _bash-it_modify_config_files() {
 			esac
 		done
 	fi
-	if [[ $append_to_config ]]; then
+	if [[ -n "${append_to_config}" ]]; then
 		# backup/append
 		_bash-it_backup_append
 	else
@@ -174,12 +174,12 @@ done
 
 shift $((OPTIND - 1))
 
-if [[ $silent ]] && [[ $interactive ]]; then
+if [[ -n "${silent}" && -n "${interactive}" ]]; then
 	echo -e "\033[91mOptions --silent and --interactive are mutually exclusive. Please choose one or the other.\033[m"
 	exit 1
 fi
 
-if [[ $no_modify_config ]] && [[ $append_to_config ]]; then
+if [[ -n "${no_modify_config}" && -n "${append_to_config}" ]]; then
 	echo -e "\033[91mOptions --no-modify-config and --append-to-config are mutually exclusive. Please choose one or the other.\033[m"
 	exit 1
 fi
@@ -197,7 +197,7 @@ esac
 
 BACKUP_FILE=$CONFIG_FILE.bak
 echo "Installing bash-it"
-if ! [[ $no_modify_config ]]; then
+if [[ -z "${no_modify_config}" ]]; then
 	_bash-it_modify_config_files
 fi
 
@@ -212,10 +212,10 @@ cite _about _param _example _group _author _version
 # shellcheck source=./lib/helpers.bash
 source "$BASH_IT/lib/helpers.bash"
 
-if [[ $interactive ]] && ! [[ $silent ]]; then
+if [[ -n $interactive && -z "${silent}" ]]; then
 	for type in "aliases" "plugins" "completion"; do
-		echo -e "\033[0;32mEnabling $type\033[0m"
-		_bash-it_load_some $type
+		echo -e "\033[0;32mEnabling ${type}\033[0m"
+		_bash-it_load_some "$type"
 	done
 else
 	echo ""
@@ -230,7 +230,7 @@ fi
 echo ""
 echo -e "\033[0;32mInstallation finished successfully! Enjoy bash-it!\033[0m"
 # shellcheck disable=SC2086
-echo -e "\033[0;32mTo start using it, open a new tab or 'source "$HOME/$CONFIG_FILE"'.\033[0m"
+echo -e "\033[0;32mTo start using it, open a new tab or 'source "~/$CONFIG_FILE"'.\033[0m"
 echo ""
 echo "To show the available aliases/completions/plugins, type one of the following:"
 echo "  bash-it show aliases"
diff --git a/lib/helpers.bash b/lib/helpers.bash
old mode 100755
new mode 100644
diff --git a/lib/log.bash b/lib/log.bash
old mode 100755
new mode 100644
diff --git a/lib/search.bash b/lib/search.bash
old mode 100755
new mode 100644
diff --git a/lib/utilities.bash b/lib/utilities.bash
old mode 100755
new mode 100644
diff --git a/plugins/available/alias-completion.plugin.bash b/plugins/available/alias-completion.plugin.bash
index 0db9b04b..eb368d93 100644
--- a/plugins/available/alias-completion.plugin.bash
+++ b/plugins/available/alias-completion.plugin.bash
@@ -19,6 +19,8 @@ about-plugin 'Automatic completion of aliases'
 # Automatically add completion for all aliases to commands having completion functions
 function alias_completion {
 	local namespace="alias_completion"
+	local tmp_file completion_loader alias_name alias_tokens line completions
+	local alias_arg_words new_completion compl_func compl_wrapper
 
 	# parse function based completion definitions, where capture group 2 => function and 3 => trigger
 	local compl_regex='complete( +[^ ]+)* -F ([^ ]+) ("[^"]+"|[^ ]+)'
@@ -26,28 +28,25 @@ function alias_completion {
 	local alias_regex="alias( -- | )([^=]+)='(\"[^\"]+\"|[^ ]+)(( +[^ ]+)*)'"
 
 	# create array of function completion triggers, keeping multi-word triggers together
-	eval "local completions=($(complete -p | sed -Ene "/$compl_regex/s//'\3'/p"))"
+	eval "completions=($(complete -p | sed -Ene "/$compl_regex/s//'\3'/p"))"
 	((${#completions[@]} == 0)) && return 0
 
 	# create temporary file for wrapper functions and completions
-	local tmp_file
 	tmp_file="$(mktemp -t "${namespace}-${RANDOM}XXXXXX")" || return 1
 
-	local completion_loader
 	completion_loader="$(complete -p -D 2> /dev/null | sed -Ene 's/.* -F ([^ ]*).*/\1/p')"
 
 	# read in "<alias> '<aliased command>' '<command args>'" lines from defined aliases
-	local line
-
-	# shellcheck disable=SC2162
 	# some aliases do have backslashes that needs to be interpreted
+	# shellcheck disable=SC2162
 	while read line; do
-		eval "local alias_tokens; alias_tokens=($line)" 2> /dev/null || continue # some alias arg patterns cause an eval parse error
-		local alias_name="${alias_tokens[0]}" alias_cmd="${alias_tokens[1]}" alias_args="${alias_tokens[2]# }"
+		eval "alias_tokens=($line)" 2> /dev/null || continue # some alias arg patterns cause an eval parse error
+		# shellcheck disable=SC2154 # see `eval` above
+		alias_name="${alias_tokens[0]}" alias_cmd="${alias_tokens[1]}" alias_args="${alias_tokens[2]# }"
 
 		# skip aliases to pipes, boolean control structures and other command lists
 		# (leveraging that eval errs out if $alias_args contains unquoted shell metacharacters)
-		eval "local alias_arg_words; alias_arg_words=($alias_args)" 2> /dev/null || continue
+		eval "alias_arg_words=($alias_args)" 2> /dev/null || continue
 		# avoid expanding wildcards
 		read -a alias_arg_words <<< "$alias_args"
 
@@ -63,15 +62,15 @@ function alias_completion {
 				continue
 			fi
 		fi
-		local new_completion="$(complete -p "$alias_cmd" 2> /dev/null)"
+		new_completion="$(complete -p "$alias_cmd" 2> /dev/null)"
 
 		# create a wrapper inserting the alias arguments if any
 		if [[ -n $alias_args ]]; then
-			local compl_func="${new_completion/#* -F /}"
+			compl_func="${new_completion/#* -F /}"
 			compl_func="${compl_func%% *}"
 			# avoid recursive call loops by ignoring our own functions
 			if [[ "${compl_func#_"$namespace"::}" == "$compl_func" ]]; then
-				local compl_wrapper="_${namespace}::${alias_name}"
+				compl_wrapper="_${namespace}::${alias_name}"
 				echo "function $compl_wrapper {
                         local compl_word=\$2
                         local prec_word=\$3
diff --git a/plugins/available/cmd-returned-notify.plugin.bash b/plugins/available/cmd-returned-notify.plugin.bash
index a3050875..d9be5e4e 100644
--- a/plugins/available/cmd-returned-notify.plugin.bash
+++ b/plugins/available/cmd-returned-notify.plugin.bash
@@ -9,7 +9,7 @@ precmd_return_notification() {
 }
 
 preexec_return_notification() {
-	[ -z "${LAST_COMMAND_TIME}" ] && export LAST_COMMAND_TIME=$(date +%s)
+	[[ -z "${LAST_COMMAND_TIME}" ]] && LAST_COMMAND_TIME=$(date +%s)
 }
 
 precmd_functions+=(precmd_return_notification)
diff --git a/plugins/available/git.plugin.bash b/plugins/available/git.plugin.bash
index 6a85e7dc..3a130955 100644
--- a/plugins/available/git.plugin.bash
+++ b/plugins/available/git.plugin.bash
@@ -2,12 +2,13 @@
 cite about-plugin
 about-plugin 'git helper functions'
 
+# shellcheck disable=SC2016
 function git_remote {
-	about "adds remote $GIT_HOSTING:$1 to current repo"
+	about 'adds remote $GIT_HOSTING:$1 to current repo'
 	group "git"
 
-	echo "Running: git remote add origin ${GIT_HOSTING}:$1.git"
-	git remote add origin "$GIT_HOSTING:$1".git
+	echo "Running: git remote add origin ${GIT_HOSTING:?}:$1.git"
+	git remote add origin "${GIT_HOSTING}:${1}".git
 }
 
 function git_first_push {
@@ -24,14 +25,14 @@ function git_pub() {
 	BRANCH=$(git rev-parse --abbrev-ref HEAD)
 
 	echo "Publishing ${BRANCH} to remote origin"
-	git push -u origin "$BRANCH"
+	git push -u origin "${BRANCH}"
 }
 
 function git_revert() {
 	about 'applies changes to HEAD that revert all changes after this commit'
 	group 'git'
 
-	git reset "$1"
+	git reset "${1:?}"
 	git reset --soft "HEAD@{1}"
 	git commit -m "Revert to ${1}"
 	git reset --hard
@@ -49,9 +50,7 @@ function git_rollback() {
 	}
 
 	function commit_exists() {
-		git rev-list --quiet "$1"
-		status=$?
-		if [ $status -ne 0 ]; then
+		if git rev-list --quiet "${1:?}"; then
 			echo "Commit ${1} does not exist"
 			kill -INT $$
 		fi
@@ -61,7 +60,7 @@ function git_rollback() {
 		while true; do
 			# shellcheck disable=SC2162
 			read -p "Do you want to keep all changes from rolled back revisions in your working tree? [Y/N]" RESP
-			case $RESP in
+			case "${RESP}" in
 
 				[yY])
 					echo "Rolling back to commit ${1} with unstaged changes"
@@ -87,7 +86,7 @@ function git_rollback() {
 		while true; do
 			# shellcheck disable=SC2162
 			read -p "WARNING: This will change your history and move the current HEAD back to commit ${1}, continue? [Y/N]" RESP
-			case $RESP in
+			case "${RESP}" in
 
 				[yY])
 					keep_changes "$1"
@@ -134,8 +133,8 @@ function git_info() {
 
 		# print all remotes and thier details
 		for remote in $(git remote show); do
-			echo "$remote":
-			git remote show "$remote"
+			echo "${remote}":
+			git remote show "${remote}"
 			echo
 		done
 
@@ -172,32 +171,32 @@ function git_stats {
 		AUTHORS=$(git shortlog -sn --all | cut -f2 | cut -f1 -d' ')
 		LOGOPTS=""
 		if [ "$1" == '-w' ]; then
-			LOGOPTS="$LOGOPTS -w"
+			LOGOPTS="${LOGOPTS} -w"
 			shift
 		fi
 		if [ "$1" == '-M' ]; then
-			LOGOPTS="$LOGOPTS -M"
+			LOGOPTS="${LOGOPTS} -M"
 			shift
 		fi
 		if [ "$1" == '-C' ]; then
-			LOGOPTS="$LOGOPTS -C --find-copies-harder"
+			LOGOPTS="${LOGOPTS} -C --find-copies-harder"
 			shift
 		fi
-		for a in $AUTHORS; do
+		for a in ${AUTHORS}; do
 			echo '-------------------'
-			echo "Statistics for: $a"
+			echo "Statistics for: ${a}"
 			echo -n "Number of files changed: "
 			# shellcheck disable=SC2086
-			git log $LOGOPTS --all --numstat --format="%n" --author="$a" | cut -f3 | sort -iu | wc -l
+			git log ${LOGOPTS} --all --numstat --format="%n" --author="${a}" | cut -f3 | sort -iu | wc -l
 			echo -n "Number of lines added: "
 			# shellcheck disable=SC2086
-			git log $LOGOPTS --all --numstat --format="%n" --author="$a" | cut -f1 | awk '{s+=$1} END {print s}'
+			git log ${LOGOPTS} --all --numstat --format="%n" --author="${a}" | cut -f1 | awk '{s+=$1} END {print s}'
 			echo -n "Number of lines deleted: "
 			# shellcheck disable=SC2086
-			git log $LOGOPTS --all --numstat --format="%n" --author="$a" | cut -f2 | awk '{s+=$1} END {print s}'
+			git log ${LOGOPTS} --all --numstat --format="%n" --author="${a}" | cut -f2 | awk '{s+=$1} END {print s}'
 			echo -n "Number of merges: "
 			# shellcheck disable=SC2086
-			git log $LOGOPTS --all --merges --author="$a" | grep -c '^commit'
+			git log ${LOGOPTS} --all --merges --author="${a}" | grep -c '^commit'
 		done
 	else
 		echo "you're currently not in a git repository"
@@ -212,18 +211,16 @@ function gittowork() {
 
 	result=$(curl -L "https://www.gitignore.io/api/$1" 2> /dev/null)
 
-	if [[ $result =~ ERROR ]]; then
+	if [[ "${result}" =~ ERROR ]]; then
 		echo "Query '$1' has no match. See a list of possible queries with 'gittowork list'"
-	elif [[ $1 = list ]]; then
-		echo "$result"
+	elif [[ $1 == list ]]; then
+		echo "${result}"
 	else
 		if [[ -f .gitignore ]]; then
-			result=$(echo "$result" | grep -v "# Created by http://www.gitignore.io")
+			result=$(grep -v "# Created by http://www.gitignore.io" <<< "${result}")
 			echo ".gitignore already exists, appending..."
-			echo "$result" >> .gitignore
-		else
-			echo "$result" > .gitignore
 		fi
+		echo "${result}" >> .gitignore
 	fi
 }
 
@@ -257,7 +254,7 @@ function gitignore-reload() {
 	fi
 
 	# Prompt user to commit or stash changes and exit
-	if [ $err = 1 ]; then
+	if [[ "${err}" == 1 ]]; then
 		echo >&2 "Please commit or stash them."
 	fi
 
@@ -265,7 +262,7 @@ function gitignore-reload() {
 
 	# If we're here, then there are no uncommited or unstaged changes dangling around.
 	# Proceed to reload .gitignore
-	if [ $err = 0 ]; then
+	if [[ "${err}" == 0 ]]; then
 		# Remove all cached files
 		git rm -r --cached .
 
@@ -290,6 +287,7 @@ function git-changelog() {
 		return 1
 	fi
 
+	# shellcheck disable=SC2155
 	local NEXT=$(date +%F)
 
 	if [[ "$2" == "md" ]]; then
@@ -298,9 +296,9 @@ function git-changelog() {
 		# shellcheck disable=SC2162
 		git log "$1" --no-merges --format="%cd" --date=short | sort -u -r | while read DATE; do
 			echo
-			echo "### $DATE"
-			git log --no-merges --format=" * (%h) %s by [%an](mailto:%ae)" --since="$DATE 00:00:00" --until="$DATE 24:00:00"
-			NEXT=$DATE
+			echo "### ${DATE}"
+			git log --no-merges --format=" * (%h) %s by [%an](mailto:%ae)" --since="${DATE} 00:00:00" --until="${DATE} 24:00:00"
+			NEXT=${DATE}
 		done
 	else
 		echo "CHANGELOG $1"
@@ -309,9 +307,10 @@ function git-changelog() {
 		# shellcheck disable=SC2162
 		git log "$1" --no-merges --format="%cd" --date=short | sort -u -r | while read DATE; do
 			echo
-			echo "[$DATE]"
-			git log --no-merges --format=" * (%h) %s by %an <%ae>" --since="$DATE 00:00:00" --until="$DATE 24:00:00"
-			NEXT=$DATE
+			echo "[${DATE}]"
+			git log --no-merges --format=" * (%h) %s by %an <%ae>" --since="${DATE} 00:00:00" --until="${DATE} 24:00:00"
+			# shellcheck disable=SC2034
+			NEXT=${DATE}
 		done
 	fi
 }
diff --git a/plugins/available/goenv.plugin.bash b/plugins/available/goenv.plugin.bash
index d00fce67..17e4a0ff 100644
--- a/plugins/available/goenv.plugin.bash
+++ b/plugins/available/goenv.plugin.bash
@@ -30,7 +30,7 @@ eval "$(goenv init - bash)"
 # If moving to a directory with a goenv version set, reload the shell
 # to ensure the shell environment matches expectations.
 _bash-it-goenv-preexec() {
-	export GOENV_OLD_VERSION="$(goenv version-name)"
+	GOENV_OLD_VERSION="$(goenv version-name)"
 }
 _bash-it-goenv-precmd() {
 	if [[ -n $GOENV_OLD_VERSION ]] && [[ "$GOENV_OLD_VERSION" != "$(goenv version-name)" ]]; then
diff --git a/plugins/available/xterm.plugin.bash b/plugins/available/xterm.plugin.bash
index 4f4fd50d..b8747a25 100644
--- a/plugins/available/xterm.plugin.bash
+++ b/plugins/available/xterm.plugin.bash
@@ -3,29 +3,37 @@ cite about-plugin
 about-plugin 'automatically set your xterm title with host and location info'
 
 _short-dirname() {
-	local dir_name=$(dirs +0)
-	[ "$SHORT_TERM_LINE" = true ] && [ "${#dir_name}" -gt 8 ] && echo "${dir_name##*/}" || echo "${dir_name}"
+	local dir_name="${PWD/~/\~}"
+	if [[ "${SHORT_TERM_LINE:-}" == true && "${#dir_name}" -gt 8 ]]; then
+		echo "${dir_name##*/}"
+	else
+		echo "${dir_name}"
+	fi
 }
 
 _short-command() {
 	local input_command="$*"
-	[ "$SHORT_TERM_LINE" = true ] && [ "${#input_command}" -gt 8 ] && echo "${input_command%% *}" || echo "${input_command}"
+	if [[ "${SHORT_TERM_LINE:-}" == true && "${#input_command}" -gt 8 ]]; then
+		echo "${input_command%% *}"
+	else
+		echo "${input_command}"
+	fi
 }
 
 set_xterm_title() {
-	local title="$1"
-	echo -ne "\033]0;$title\007"
+	local title="${1:-}"
+	echo -ne "\033]0;${title}\007"
 }
 
 precmd_xterm_title() {
-	set_xterm_title "${SHORT_USER:-${USER}}@${SHORT_HOSTNAME:-${HOSTNAME}} $(_short-dirname) $PROMPT_CHAR"
+	set_xterm_title "${SHORT_USER:-${USER}}@${SHORT_HOSTNAME:-${HOSTNAME}} $(_short-dirname) ${PROMPT_CHAR:-\$}"
 }
 
 preexec_xterm_title() {
-	set_xterm_title "$(_short-command "${1}") {$(_short-dirname)} (${SHORT_USER:-${USER}}@${SHORT_HOSTNAME:-${HOSTNAME}})"
+	set_xterm_title "$(_short-command "${1:-}") {$(_short-dirname)} (${SHORT_USER:-${USER}}@${SHORT_HOSTNAME:-${HOSTNAME}})"
 }
 
-case "$TERM" in
+case "${TERM:-dumb}" in
 	xterm* | rxvt*)
 		precmd_functions+=(precmd_xterm_title)
 		preexec_functions+=(preexec_xterm_title)
diff --git a/scripts/reloader.bash b/scripts/reloader.bash
old mode 100644
new mode 100755
index f22de67e..4bc24941
--- a/scripts/reloader.bash
+++ b/scripts/reloader.bash
@@ -5,6 +5,7 @@ function _set-prefix-based-on-path()
 {
   filename=$(_bash-it-get-component-name-from-path "$1")
   extension=$(_bash-it-get-component-type-from-path "$1")
+	# shellcheck disable=SC2034
   BASH_IT_LOG_PREFIX="$extension: $filename: "
 }
 
@@ -15,7 +16,7 @@ if [[ "$1" != "skip" ]] && [[ -d "$BASH_IT/enabled" ]]; then
     alias|completion|plugin)
       _bash_it_config_type=$1
       _log_debug "Loading enabled $1 components..." ;;
-    *|'')
+    ''|*)
       _log_debug "Loading all enabled components..." ;;
   esac
 
diff --git a/themes/90210/90210.theme.bash b/themes/90210/90210.theme.bash
index 180764c8..3db3f17b 100644
--- a/themes/90210/90210.theme.bash
+++ b/themes/90210/90210.theme.bash
@@ -1,4 +1,7 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
+
 SCM_THEME_PROMPT_DIRTY=" ${red}✗"
 SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓"
 SCM_THEME_PROMPT_PREFIX=" |"
@@ -11,7 +14,7 @@ GIT_THEME_PROMPT_SUFFIX="${green}|"
 
 # Nicely formatted terminal prompt
 function prompt_command() {
-	export PS1="\n${bold_black}[${blue}\@${bold_black}]-${bold_black}[${green}\u${yellow}@${green}\h${bold_black}]-${bold_black}[${purple}\w${bold_black}]-$(scm_prompt_info)\n${reset_color}\$ "
+	PS1="\n${bold_black}[${blue}\@${bold_black}]-${bold_black}[${green}\u${yellow}@${green}\h${bold_black}]-${bold_black}[${purple}\w${bold_black}]-$(scm_prompt_info)\n${reset_color}\$ "
 }
 
 safe_append_prompt_command prompt_command
diff --git a/themes/agnoster/agnoster.theme.bash b/themes/agnoster/agnoster.theme.bash
index ba3e2c9a..20c184f3 100644
--- a/themes/agnoster/agnoster.theme.bash
+++ b/themes/agnoster/agnoster.theme.bash
@@ -1,4 +1,5 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
 # vim: ft=bash ts=2 sw=2 sts=2
 #
 # agnoster's Theme - https://gist.github.com/3712874
@@ -220,7 +221,7 @@ prompt_virtualenv() {
 
 # Context: user@hostname (who am I and where am I)
 prompt_context() {
-	local user=$(whoami)
+	local user="${USER:-${LOGNAME:?}}"
 
 	if [[ $user != "$DEFAULT_USER" || -n $SSH_CLIENT ]]; then
 		prompt_segment black default "$user@\h"
diff --git a/themes/atomic/atomic.theme.bash b/themes/atomic/atomic.theme.bash
index 6bde6801..03dc9e95 100644
--- a/themes/atomic/atomic.theme.bash
+++ b/themes/atomic/atomic.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 # Atomic Bash Prompt for Bash-it
 # By lfelipe base on the theme brainy of MunifTanjim
diff --git a/themes/bakke/bakke.theme.bash b/themes/bakke/bakke.theme.bash
index 725350a0..d7bfbbe8 100644
--- a/themes/bakke/bakke.theme.bash
+++ b/themes/bakke/bakke.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 SCM_THEME_PROMPT_DIRTY=" ${red}✗"
 SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓"
diff --git a/themes/barbuk/barbuk.theme.bash b/themes/barbuk/barbuk.theme.bash
index 8e09d4be..b614d148 100644
--- a/themes/barbuk/barbuk.theme.bash
+++ b/themes/barbuk/barbuk.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 # Theme custom glyphs
 SCM_GIT_CHAR_GITLAB=${BARBUK_GITLAB_CHAR:='  '}
diff --git a/themes/base.theme.bash b/themes/base.theme.bash
index 5cc791b4..1e0409d3 100644
--- a/themes/base.theme.bash
+++ b/themes/base.theme.bash
@@ -1,4 +1,5 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
 
 CLOCK_CHAR_THEME_PROMPT_PREFIX=''
 CLOCK_CHAR_THEME_PROMPT_SUFFIX=''
@@ -130,12 +131,11 @@ function scm {
 }
 
 scm_prompt() {
-	local CHAR=$(scm_char)
+	local CHAR
+	CHAR="$(scm_char)"
 	local format=${SCM_PROMPT_FORMAT:-'[%s%s]'}
 
-	if [[ $CHAR = "$SCM_NONE_CHAR" ]]; then
-		return
-	else
+	if [[ "${CHAR}" != "$SCM_NONE_CHAR" ]]; then
 		# shellcheck disable=2059
 		printf "$format\n" "$CHAR" "$(scm_prompt_info)"
 	fi
@@ -352,15 +352,15 @@ function svn_prompt_vars {
 # - .hg is located in ~/Projects/Foo/.hg
 # - get_hg_root starts at ~/Projects/Foo/Bar and sees that there is no .hg directory, so then it goes into ~/Projects/Foo
 function get_hg_root {
-	local CURRENT_DIR=$(pwd)
+	local CURRENT_DIR="${PWD}"
 
-	while [ "$CURRENT_DIR" != "/" ]; do
-		if [ -d "$CURRENT_DIR/.hg" ]; then
+	while [[ "${CURRENT_DIR:-/}" != "/" ]]; do
+		if [[ -d "$CURRENT_DIR/.hg" ]]; then
 			echo "$CURRENT_DIR/.hg"
 			return
 		fi
 
-		CURRENT_DIR=$(dirname "$CURRENT_DIR")
+		CURRENT_DIR="${CURRENT_DIR%/*}"
 	done
 }
 
@@ -552,7 +552,7 @@ function prompt_char {
 
 function battery_char {
 	if [[ "${THEME_BATTERY_PERCENTAGE_CHECK}" = true ]]; then
-		echo -e "${bold_red}$(battery_percentage)%"
+		echo -e "${bold_red:-}$(battery_percentage)%"
 	fi
 }
 
@@ -594,7 +594,7 @@ function __check_precmd_conflict() {
 function safe_append_prompt_command {
 	local prompt_re
 
-	if [ "${__bp_imported}" == "defined" ]; then
+	if [ "${__bp_imported:-missing}" == "defined" ]; then
 		# We are using bash-preexec
 		if ! __check_precmd_conflict "${1}"; then
 			precmd_functions+=("${1}")
@@ -609,7 +609,7 @@ function safe_append_prompt_command {
 			prompt_re="\<${1}\>"
 		fi
 
-		if [[ ${PROMPT_COMMAND} =~ ${prompt_re} ]]; then
+		if [[ ${PROMPT_COMMAND[*]:-} =~ ${prompt_re} ]]; then
 			return
 		elif [[ -z ${PROMPT_COMMAND} ]]; then
 			PROMPT_COMMAND="${1}"
diff --git a/themes/binaryanomaly/binaryanomaly.theme.bash b/themes/binaryanomaly/binaryanomaly.theme.bash
index c2efa237..c4488c4c 100644
--- a/themes/binaryanomaly/binaryanomaly.theme.bash
+++ b/themes/binaryanomaly/binaryanomaly.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 # Detect whether a reboot is required
 function show_reboot_required() {
diff --git a/themes/bira/bira.theme.bash b/themes/bira/bira.theme.bash
index ae8f0efe..7db03000 100644
--- a/themes/bira/bira.theme.bash
+++ b/themes/bira/bira.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 SCM_THEME_PROMPT_PREFIX=" ${yellow}‹"
 SCM_THEME_PROMPT_SUFFIX="›${reset_color}"
diff --git a/themes/bobby-python/bobby-python.theme.bash b/themes/bobby-python/bobby-python.theme.bash
index 9144e251..ebb3eab0 100644
--- a/themes/bobby-python/bobby-python.theme.bash
+++ b/themes/bobby-python/bobby-python.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 SCM_THEME_PROMPT_DIRTY=" ${red}✗"
 SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓"
diff --git a/themes/bobby/bobby.theme.bash b/themes/bobby/bobby.theme.bash
index bdf388f7..98d2cd8d 100644
--- a/themes/bobby/bobby.theme.bash
+++ b/themes/bobby/bobby.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 SCM_THEME_PROMPT_DIRTY=" ${red}✗"
 SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓"
diff --git a/themes/brainy/brainy.theme.bash b/themes/brainy/brainy.theme.bash
index db8377ba..e1c36175 100644
--- a/themes/brainy/brainy.theme.bash
+++ b/themes/brainy/brainy.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 # Brainy Bash Prompt for Bash-it
 # by MunifTanjim
diff --git a/themes/brunton/brunton.theme.bash b/themes/brunton/brunton.theme.bash
index 27b822ca..166fcc84 100644
--- a/themes/brunton/brunton.theme.bash
+++ b/themes/brunton/brunton.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 SCM_THEME_PROMPT_PREFIX=""
 SCM_THEME_PROMPT_SUFFIX=""
diff --git a/themes/candy/candy.theme.bash b/themes/candy/candy.theme.bash
index be53d373..7753e934 100644
--- a/themes/candy/candy.theme.bash
+++ b/themes/candy/candy.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 function prompt_command() {
 	PS1="${green}\u@\h $(clock_prompt) ${reset_color}${white}\w${reset_color}$(scm_prompt_info)${blue} →${bold_blue} ${reset_color} ${normal}"
diff --git a/themes/colors.theme.bash b/themes/colors.theme.bash
index fbb1dc5c..d5044d05 100644
--- a/themes/colors.theme.bash
+++ b/themes/colors.theme.bash
@@ -1,4 +1,6 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
+# shellcheck disable=SC2005
+# shellcheck disable=SC2034
 
 function __ {
   echo "$@"
diff --git a/themes/easy/easy.theme.bash b/themes/easy/easy.theme.bash
index a48eb824..7e2e3389 100644
--- a/themes/easy/easy.theme.bash
+++ b/themes/easy/easy.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 SCM_THEME_PROMPT_PREFIX="${bold_green}[ ${normal}"
 SCM_THEME_PROMPT_SUFFIX="${bold_green} ] "
diff --git a/themes/modern/modern.theme.bash b/themes/modern/modern.theme.bash
index 3a51267c..eadb0762 100644
--- a/themes/modern/modern.theme.bash
+++ b/themes/modern/modern.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 SCM_THEME_PROMPT_PREFIX=""
 SCM_THEME_PROMPT_SUFFIX=""
diff --git a/themes/powerline/powerline.base.bash b/themes/powerline/powerline.base.bash
index 98bcd82c..ade3670d 100644
--- a/themes/powerline/powerline.base.bash
+++ b/themes/powerline/powerline.base.bash
@@ -1,4 +1,7 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
+
 # Define this here so it can be used by all of the Powerline themes
 THEME_CHECK_SUDO=${THEME_CHECK_SUDO:=true}
 
@@ -139,7 +142,7 @@ function __powerline_scm_prompt() {
 }
 
 function __powerline_cwd_prompt() {
-	local cwd=$(pwd | sed "s|^${HOME}|~|")
+	local cwd="${PWD/$HOME/\~}"
 
 	echo "${cwd}|${CWD_THEME_PROMPT_COLOR}"
 }
@@ -157,10 +160,10 @@ function __powerline_clock_prompt() {
 }
 
 function __powerline_battery_prompt() {
-	local color=""
-	local battery_status="$(battery_percentage 2> /dev/null)"
+	local color="" battery_status
+	battery_status="$(battery_percentage 2> /dev/null)"
 
-	if [[ -z "${battery_status}" ]] || [[ "${battery_status}" = "-1" ]] || [[ "${battery_status}" = "no" ]]; then
+	if [[ -z "${battery_status}" || "${battery_status}" == "-1" || "${battery_status}" == "no" ]]; then
 		true
 	else
 		if [[ "$((10#${battery_status}))" -le 5 ]]; then
@@ -176,7 +179,7 @@ function __powerline_battery_prompt() {
 }
 
 function __powerline_in_vim_prompt() {
-	if [ -n "$VIMRUNTIME" ]; then
+	if [[ -n "$VIMRUNTIME" ]]; then
 		echo "${IN_VIM_THEME_PROMPT_TEXT}|${IN_VIM_THEME_PROMPT_COLOR}"
 	fi
 }
@@ -221,7 +224,8 @@ function __powerline_command_number_prompt() {
 }
 
 function __powerline_duration_prompt() {
-	local duration=$(_command_duration)
+	local duration
+	duration=$(_command_duration)
 	[[ -n "$duration" ]] && echo "${duration}|${COMMAND_DURATION_PROMPT_COLOR}"
 }
 
@@ -265,7 +269,7 @@ function __powerline_last_status_prompt() {
 
 function __powerline_prompt_command() {
 	local last_status="$?" ## always the first
-	local separator_char="${POWERLINE_PROMPT_CHAR}"
+	local separator_char="${POWERLINE_PROMPT_CHAR}" info prompt_color
 
 	LEFT_PROMPT=""
 	SEGMENTS_AT_LEFT=0
@@ -277,7 +281,7 @@ function __powerline_prompt_command() {
 
 	## left prompt ##
 	for segment in $POWERLINE_PROMPT; do
-		local info="$(__powerline_"${segment}"_prompt)"
+		info="$(__powerline_"${segment}"_prompt)"
 		[[ -n "${info}" ]] && __powerline_left_segment "${info}"
 	done
 
@@ -289,7 +293,7 @@ function __powerline_prompt_command() {
 
 	# By default we try to match the prompt to the adjacent segment's background color,
 	# but when part of the prompt exists within that segment, we instead match the foreground color.
-	local prompt_color="$(set_color "${LAST_SEGMENT_COLOR}" -)"
+	prompt_color="$(set_color "${LAST_SEGMENT_COLOR}" -)"
 	if [[ -n "${LEFT_PROMPT}" ]] && [[ -n "${POWERLINE_LEFT_LAST_SEGMENT_PROMPT_CHAR}" ]]; then
 		LEFT_PROMPT+="$(set_color - "${LAST_SEGMENT_COLOR}")${POWERLINE_LEFT_LAST_SEGMENT_PROMPT_CHAR}"
 		prompt_color="${normal}"
diff --git a/themes/powerline/powerline.theme.bash b/themes/powerline/powerline.theme.bash
index d7ac77ed..49b397aa 100644
--- a/themes/powerline/powerline.theme.bash
+++ b/themes/powerline/powerline.theme.bash
@@ -1,4 +1,5 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
 
 # shellcheck source=../../themes/powerline/powerline.base.bash
 . "$BASH_IT/themes/powerline/powerline.base.bash"
diff --git a/themes/pure/pure.theme.bash b/themes/pure/pure.theme.bash
index 3672a72c..99476f4a 100644
--- a/themes/pure/pure.theme.bash
+++ b/themes/pure/pure.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 # scm theming
 SCM_THEME_PROMPT_PREFIX="|"
diff --git a/themes/purity/purity.theme.bash b/themes/purity/purity.theme.bash
index 8fc03bf3..22a3fbfb 100644
--- a/themes/purity/purity.theme.bash
+++ b/themes/purity/purity.theme.bash
@@ -1,4 +1,6 @@
 # shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+# shellcheck disable=SC2154 #TODO: fix these all.
 
 SCM_THEME_PROMPT_DIRTY=" ${bold_red}⊘${normal}"
 SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓${normal}"
@@ -26,8 +28,8 @@ venv_prompt() {
 }
 
 function prompt_command() {
-	retval=$?
-	local ret_status="$([ $retval -eq 0 ] && echo -e "$STATUS_THEME_PROMPT_OK" || echo -e "$STATUS_THEME_PROMPT_BAD")"
+	local retval=$? ret_status
+	ret_status="$([ $retval -eq 0 ] && echo -e "$STATUS_THEME_PROMPT_OK" || echo -e "$STATUS_THEME_PROMPT_BAD")"
 	PS1="\n${PURITY_THEME_PROMPT_COLOR}\w $(scm_prompt_info)\n${ret_status}$(venv_prompt)"
 }