diff --git a/rc/fzf.kak b/rc/fzf.kak
index 7c2811a..7f12c55 100644
--- a/rc/fzf.kak
+++ b/rc/fzf.kak
@@ -104,10 +104,10 @@ fzf-horizontal -params .. %{ evaluate-commands %{
 
 define-command -hidden -docstring "wrapper command to create new terminal" \
 fzf-window -params .. %{ evaluate-commands %sh{
-    if [ -n "$kak_client_env_TMUX" ]; then
+    if [ -n "${kak_client_env_TMUX:-}" ]; then
         printf "%s\n" 'tmux-terminal-window kak -c %val{session} -e "%arg{@}"'
     else
-        printf "%s\n" "$kak_opt_fzf_terminal_command"
+        printf "%s\n" "${kak_opt_fzf_terminal_command:?}"
     fi
 }}
 
@@ -136,12 +136,12 @@ Switches:
 -post-action"
 } \
 fzf -params .. %{ evaluate-commands %sh{
-    fzf_impl="${kak_opt_fzf_implementation}"
+    fzf_impl="${kak_opt_fzf_implementation:?}"
 
-    [ "${kak_opt_fzf_use_main_selection}" = "true" ] && \
-    [ $(printf "%s" "${kak_selection}" | wc -m) -gt 1 ] && \
-    [ $(printf "%s" "${kak_selection}" | wc -l) -eq 1 ] && \
-    default_query="-i -q ${kak_selection}"
+    [ "${kak_opt_fzf_use_main_selection:-}" = "true" ] && \
+    [ "$(printf "%s" "${kak_selection:-}" | wc -m)" -gt 1 ] && \
+    [ "$(printf "%s" "${kak_selection:-}" | wc -l)" -eq 1 ] && \
+    default_query="-i -q ${kak_selection:-}"
 
     while [ $# -gt 0 ]; do
         case $1 in
@@ -162,29 +162,29 @@ fzf -params .. %{ evaluate-commands %sh{
 
     if [ "${preview}" = "true" ]; then
         # bake position option to define them at runtime
-        [ -n "${kak_client_env_TMUX}" ] && tmux_height="${kak_opt_fzf_preview_tmux_height}"
-        case ${kak_opt_fzf_preview_pos} in
-            (top|up)      preview_position="pos=top:${kak_opt_fzf_preview_height};" ;;
-            (bottom|down) preview_position="pos=down:${kak_opt_fzf_preview_height};" ;;
-            (right)       preview_position="pos=right:${kak_opt_fzf_preview_width};" ;;
-            (left)        preview_position="pos=left:${kak_opt_fzf_preview_width};" ;;
-            (auto|*)      preview_position="sleep 0.1; [ \$(tput cols) -gt \$(expr \$(tput lines) \* 2) ] && pos=right:${kak_opt_fzf_preview_width} || pos=top:${kak_opt_fzf_preview_height};"
+        [ -n "${kak_client_env_TMUX:-}" ] && tmux_height="${kak_opt_fzf_preview_tmux_height:-}"
+        case ${kak_opt_fzf_preview_pos:-} in
+            (top|up)      preview_position="pos=top:${kak_opt_fzf_preview_height:-};" ;;
+            (bottom|down) preview_position="pos=down:${kak_opt_fzf_preview_height:-};" ;;
+            (right)       preview_position="pos=right:${kak_opt_fzf_preview_width:-};" ;;
+            (left)        preview_position="pos=left:${kak_opt_fzf_preview_width:-};" ;;
+            (auto|*)      preview_position="sleep 0.1; [ \$(tput cols) -gt \$(expr \$(tput lines) \* 2) ] && pos=right:${kak_opt_fzf_preview_width:-} || pos=top:${kak_opt_fzf_preview_height:-};"
         esac
 
         # handle preview if not defined explicitly with `-preview-cmd'
-        if [ ${kak_opt_fzf_preview} = "true" ] && [ -z "${preview_cmd}" ]; then
-            case ${kak_opt_fzf_highlight_command} in
+        if [ "${kak_opt_fzf_preview:-}" = "true" ] && [ -z "${preview_cmd}" ]; then
+            case ${kak_opt_fzf_highlight_command:-} in
                 (bat)       highlight_cmd="bat --color=always --style=plain {}" ;;
                 (coderay)   highlight_cmd="coderay {}" ;;
                 (highlight) highlight_cmd="highlight --failsafe -O ansi {}" ;;
                 (rouge)     highlight_cmd="rougify {}" ;;
                 (*)         highlight_cmd="${kak_opt_fzf_highlight_command}" ;;
             esac
-            preview_cmd="--preview '(${highlight_cmd} || cat {}) 2>/dev/null | head -n ${kak_opt_fzf_preview_lines}' --preview-window=\${pos}"
+            preview_cmd="--preview '(${highlight_cmd} || cat {}) 2>/dev/null | head -n ${kak_opt_fzf_preview_lines:-}' --preview-window=\${pos}"
         fi
     fi
 
-    fzf_tmp=$(mktemp -d ${TMPDIR:-/tmp}/fzf.kak.XXXXXX)
+    fzf_tmp=$(mktemp -d "${TMPDIR:-/tmp}"/fzf.kak.XXXXXX)
     fzfcmd="${fzf_tmp}/fzfcmd"
     result="${fzf_tmp}/result"
 
@@ -197,19 +197,19 @@ fzf -params .. %{ evaluate-commands %sh{
             printf "%s\n" "SHELL=${shell_path}"
         fi
         # compose entire fzf command with all args into single file which will be executed later
-        printf "%s\n" "export FZF_DEFAULT_OPTS=\"$kak_opt_fzf_default_opts\""
+        printf "%s\n" "export FZF_DEFAULT_OPTS=\"${kak_opt_fzf_default_opts:-}\""
         printf "%s\n" "cd \"${PWD}\" && ${preview_position} ${items_cmd} ${fzf_impl} ${default_query} ${fzf_args} ${preview_cmd} ${filter} > ${result}"
         printf "%s\n" "rm ${fzfcmd}"
-    ) >> ${fzfcmd}
-    chmod 755 ${fzfcmd}
+    ) >> "${fzfcmd}"
+    chmod 755 "${fzfcmd}"
 
     if [ -n "${kak_client_env_TMUX}" ]; then
         # set default height if not set already
-        [ -z "${tmux_height}" ] && tmux_height=${kak_opt_fzf_tmux_height}
+        [ -z "${tmux_height}" ] && tmux_height=${kak_opt_fzf_tmux_height:-}
         # if height contains `%' then `-p' will be used
         [ -n "${tmux_height%%*%}" ] && measure="-l" || measure="-p"
         # `terminal' doesn't support any kind of width and height parameters, so tmux panes are created by tmux itself
-        cmd="nop %sh{ command tmux split-window -t '${kak_client_env_TMUX_PANE}' ${measure} ${tmux_height%%%*} env ${fzfcmd} < /dev/null > /dev/null 2>&1 }"
+        cmd="nop %sh{ command tmux split-window -t '${kak_client_env_TMUX_PANE:-}' ${measure} ${tmux_height%%%*} env ${fzfcmd} < /dev/null > /dev/null 2>&1 }"
     else
         cmd="${kak_opt_fzf_terminal_command%% *} %{${fzfcmd}}"
     fi
@@ -217,20 +217,20 @@ fzf -params .. %{ evaluate-commands %sh{
     printf "%s\n" "${cmd}"
 
     # main loop
-    (   while [ -e ${fzfcmd} ]; do sleep 0.1; done
-        if [ -s ${result} ]; then
+    (   while [ -e "${fzfcmd}" ]; do sleep 0.1; done
+        if [ -s "${result}" ]; then
             (
                 while read -r line; do
                     case ${line} in
-                        (${kak_opt_fzf_window_map})     wincmd="fzf-window"     ;;
-                        (${kak_opt_fzf_vertical_map})   wincmd="fzf-vertical"   ;;
-                        (${kak_opt_fzf_horizontal_map}) wincmd="fzf-horizontal" ;;
-                        (*)                             item=${line} ;;
+                        ("${kak_opt_fzf_window_map:-}")     wincmd="fzf-window"     ;;
+                        ("${kak_opt_fzf_vertical_map:-}")   wincmd="fzf-vertical"   ;;
+                        ("${kak_opt_fzf_horizontal_map:-}") wincmd="fzf-horizontal" ;;
+                        (*)                                 item=${line} ;;
                     esac
                     if [ -n "${item}" ]; then
                         item=$(printf "%s\n" "${item}" | sed "s/@/@@/g;s/&/&&/g")
                         kakoune_cmd=$(printf "%s\n" "${kakoune_cmd}" | sed "s/&/&&/g")
-                        printf "%s\n" "evaluate-commands -client ${kak_client} ${wincmd} %&${kakoune_cmd} %@${item}@&"
+                        printf "%s\n" "evaluate-commands -client ${kak_client:?} ${wincmd} %&${kakoune_cmd} %@${item}@&"
                         break
                     fi
                 done
@@ -243,9 +243,9 @@ fzf -params .. %{ evaluate-commands %sh{
                     post_action=$(printf "%s\n" "${post_action}" | sed "s/&/&&/g")
                     printf "%s\n" "evaluate-commands -client ${kak_client} %&${post_action}&"
                 fi
-            ) < ${result} | kak -p ${kak_session}
+            ) < "${result}" | kak -p "${kak_session:?}"
         fi
-        rm -rf ${fzf_tmp}
+        rm -rf "${fzf_tmp}"
     ) > /dev/null 2>&1 < /dev/null &
 }}
 
diff --git a/rc/modules/VCS/fzf-bzr.kak b/rc/modules/VCS/fzf-bzr.kak
index cdd10f8..a25c8fa 100644
--- a/rc/modules/VCS/fzf-bzr.kak
+++ b/rc/modules/VCS/fzf-bzr.kak
@@ -24,7 +24,7 @@ define-command -hidden fzf-bzr %{ evaluate-commands %sh{
         (bzr)  cmd="(cd $repo_root && bzr ls -R --versioned)" ;;
         (*)    cmd=$kak_opt_fzf_bzr_command ;;
     esac
-    [ ! -z "${kak_client_env_TMUX}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
+    [ -n "${kak_client_env_TMUX}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
     printf "%s\n" "fzf -kak-cmd %{edit -existing} -items-cmd %{$cmd} -fzf-args %{-m --expect $kak_opt_fzf_window_map $additional_flags} -filter %{perl -pe \"if (/$kak_opt_fzf_window_map|$kak_opt_fzf_vertical_map|$kak_opt_fzf_horizontal_map|^$/) {} else {print \\\"$repo_root/\\\"}\"}"
 }}
 
diff --git a/rc/modules/fzf-buffer.kak b/rc/modules/fzf-buffer.kak
index 7de2205..b318c01 100644
--- a/rc/modules/fzf-buffer.kak
+++ b/rc/modules/fzf-buffer.kak
@@ -11,7 +11,7 @@ provide-module fzf-buffer %§
 
 define-command -hidden fzf-buffer %{ evaluate-commands %sh{
     buffers=""
-    eval "set -- $kak_quoted_buflist"
+    eval "set -- ${kak_quoted_buflist:?}"
     while [ $# -gt 0 ]; do
         buffers="$1
 $buffers"
@@ -20,19 +20,19 @@ $buffers"
 
     message="Set buffer to edit in current client.
 <ret>: switch to selected buffer.
-$kak_opt_fzf_window_map: open buffer in new window"
-    [ ! -z "${kak_client_env_TMUX}" ] && tmux_keybindings="
-$kak_opt_fzf_horizontal_map: open buffer in horizontal split
-$kak_opt_fzf_vertical_map: open buffer in vertical split"
+${kak_opt_fzf_window_map:?}: open buffer in new window"
+    [ -n "${kak_client_env_TMUX:-}" ] && tmux_keybindings="
+${kak_opt_fzf_horizontal_map:-}: open buffer in horizontal split
+${kak_opt_fzf_vertical_map:-}: open buffer in vertical split"
     printf "%s\n" "info -title 'fzf buffer' '$message$tmux_keybindings'"
-    [ ! -z "${kak_client_env_TMUX}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
+    [ -n "${kak_client_env_TMUX:-}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
 
     printf "%s\n" "fzf -kak-cmd %{buffer} -items-cmd %{printf \"%s\n\" \"$buffers\"} -fzf-args %{--expect $kak_opt_fzf_window_map $additional_flags}"
 }}
 
 define-command -hidden fzf-delete-buffer %{ evaluate-commands %sh{
     buffers=""
-    eval "set -- $kak_quoted_buflist"
+    eval "set -- ${kak_quoted_buflist:?}"
     while [ $# -gt 0 ]; do
         buffers="$1
 $buffers"
@@ -42,7 +42,7 @@ $buffers"
     message="Delete buffer.
 <ret>: delete selected buffer."
     printf "%s\n" "info -title 'fzf delete-buffer' '$message'"
-    printf "%s\n" "fzf -kak-cmd %{delete-buffer} -multiple-cmd %{delete-buffer} -items-cmd %{printf \"%s\n\" \"$buffers\"} -fzf-args %{-m --expect $kak_opt_fzf_window_map $additional_flags}"
+    printf "%s\n" "fzf -kak-cmd %{delete-buffer} -multiple-cmd %{delete-buffer} -items-cmd %{printf \"%s\n\" \"$buffers\"} -fzf-args %{-m --expect ${kak_opt_fzf_window_map:?} ${additional_flags:-}}"
 }}
 
 §
diff --git a/rc/modules/fzf-cd.kak b/rc/modules/fzf-cd.kak
index f4917ec..d5f7145 100644
--- a/rc/modules/fzf-cd.kak
+++ b/rc/modules/fzf-cd.kak
@@ -30,16 +30,15 @@ declare-option -docstring 'maximum amount of previewed directories' \
 int fzf_preview_dirs '300'
 
 define-command -hidden fzf-cd %{ evaluate-commands %sh{
-    tmux_height=$kak_opt_fzf_tmux_height
     printf '%s\n' "info -title %{fzf change directory} %{Change the server's working directory
 current path: $(pwd)}"
-    case $kak_opt_fzf_cd_command in
+    case ${kak_opt_fzf_cd_command:-} in
         (find) items_command="(echo .. && find . \( -path '*/.svn*' -o -path '*/.git*' \) -prune -o -type d -print)" ;;
         (*)    items_command=$kak_opt_fzf_cd_command ;;
     esac
-    if [ "$kak_opt_fzf_cd_preview" = "true" ]; then
+    if [ "${kak_opt_fzf_cd_preview:-}" = "true" ]; then
         preview_flag="-preview"
-        preview="--preview '($kak_opt_cd_preview_command) 2>/dev/null | head -n $kak_opt_fzf_preview_dirs'"
+        preview="--preview '(${kak_opt_cd_preview_command:-}) 2>/dev/null | head -n ${kak_opt_fzf_preview_dirs:-0}'"
     fi
     printf "%s\n" "fzf $preview_flag -kak-cmd %{change-directory} -items-cmd %{$items_command} -preview-cmd %{$preview} -post-action %{fzf-cd}"
 }}
diff --git a/rc/modules/fzf-ctags.kak b/rc/modules/fzf-ctags.kak
index 9f4e872..af5f062 100644
--- a/rc/modules/fzf-ctags.kak
+++ b/rc/modules/fzf-ctags.kak
@@ -23,9 +23,9 @@ try %{
 # this huge try block defines filetype aware filter mappings for separate fzf-ctags mode
 define-command -hidden fzf-setup-filter-tags %{
     evaluate-commands %sh{
-        [ "$opt_fzf_tag_filters_defined" = "true" ] && exit
+        [ "${kak_opt_fzf_tag_filters_defined:-}" = "true" ] && exit
 
-        case $kak_opt_filetype in
+        case ${kak_opt_filetype:-} in
             (ada) printf "%s\n" "
                 map global fzf-ctags '<a-p>' ': fzf-tag P<ret>' -docstring 'package specifications'
                 map global fzf-ctags 'p'     ': fzf-tag p<ret>' -docstring 'packages'
@@ -898,7 +898,7 @@ define-command -hidden fzf-setup-filter-tags %{
 define-command -hidden fzf-tag -params ..2 %{ evaluate-commands %sh{
     path=$PWD
     while [ "$path" != "$HOME" ]; do
-        if [ -e "./$kak_opt_fzf_tag_file_name" ]; then
+        if [ -e "./${kak_opt_fzf_tag_file_name:-}" ]; then
             break
         else
             cd ..
@@ -914,7 +914,7 @@ define-command -hidden fzf-tag -params ..2 %{ evaluate-commands %sh{
     fi
 
     cmd="cd $path;"
-    if [ -n "$(command -v ${kak_opt_readtagscmd})" ]; then
+    if [ -n "$(command -v "${kak_opt_readtagscmd%% *}")" ]; then
         if [ -n "$1" ]; then
             cmd="${cmd} ${kak_opt_readtagscmd} -t $kak_opt_fzf_tag_file_name -Q '(eq? \$kind \"$1\")' -l"
         else
@@ -928,15 +928,15 @@ define-command -hidden fzf-tag -params ..2 %{ evaluate-commands %sh{
 
     message="Jump to a symbol''s definition
 <ret>: open tag in new buffer
-$kak_opt_fzf_window_map: open tag in new terminal"
+${kak_opt_fzf_window_map:?}: open tag in new terminal"
 
-    [ -n "${kak_client_env_TMUX}" ] && tmux_keybindings="
-$kak_opt_fzf_horizontal_map: open tag in horizontal split
-$kak_opt_fzf_vertical_map: open tag in vertical split"
+    [ -n "${kak_client_env_TMUX:?}" ] && tmux_keybindings="
+${kak_opt_fzf_horizontal_map:-}: open tag in horizontal split
+${kak_opt_fzf_vertical_map:-}: open tag in vertical split"
 
     printf "%s\n" "info -title 'fzf tag' '$message$tmux_keybindings'"
 
-    [ ! -z "${kak_client_env_TMUX}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
+    [ -n "${kak_client_env_TMUX}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
     printf "%s\n" "set-option -add window ctagsfiles %{$path/$kak_opt_fzf_tag_file_name}"
     printf "%s\n" "fzf -kak-cmd %{ctags-search} -items-cmd %{$cmd | awk '!a[\$0]++'} -fzf-args %{--expect $kak_opt_fzf_window_map $additional_flags}"
 }}
diff --git a/rc/modules/fzf-file.kak b/rc/modules/fzf-file.kak
index a3ea14d..a1449e9 100644
--- a/rc/modules/fzf-file.kak
+++ b/rc/modules/fzf-file.kak
@@ -32,7 +32,7 @@ bool fzf_file_preview true
 
 
 define-command -hidden fzf-file %{ evaluate-commands %sh{
-    if [ -z "$(command -v $kak_opt_fzf_file_command)" ]; then
+    if [ -z "$(command -v "${kak_opt_fzf_file_command%% *}")" ]; then
         printf "%s\n" "echo -markup '{Information}''$kak_opt_fzf_file_command'' is not installed. Falling back to ''find'''"
         kak_opt_fzf_file_command="find"
     fi
@@ -50,14 +50,14 @@ define-command -hidden fzf-file %{ evaluate-commands %sh{
     cmd="$cmd 2>/dev/null"
     message="Open single or multiple files.
 <ret>: open file in new buffer.
-$kak_opt_fzf_window_map: open file in new terminal"
-    [ ! -z "${kak_client_env_TMUX}" ] && tmux_keybindings="
-$kak_opt_fzf_horizontal_map: open file in horizontal split
-$kak_opt_fzf_vertical_map: open file in vertical split"
+${kak_opt_fzf_window_map:?}: open file in new terminal"
+    [ -n "${kak_client_env_TMUX:-}" ] && tmux_keybindings="
+${kak_opt_fzf_horizontal_map:-}: open file in horizontal split
+${kak_opt_fzf_vertical_map:-}: open file in vertical split"
 
     printf "%s\n" "info -title 'fzf file' '$message$tmux_keybindings'"
-    [ ! -z "${kak_client_env_TMUX}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
-    [ "$kak_opt_fzf_file_preview" = "true" ] && preview_flag="-preview"
+    [ -n "${kak_client_env_TMUX}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
+    [ "${kak_opt_fzf_file_preview:-}" = "true" ] && preview_flag="-preview"
     printf "%s\n" "fzf $preview_flag -kak-cmd %{edit -existing} -items-cmd %{$cmd} -fzf-args %{-m --expect $kak_opt_fzf_window_map $additional_flags}"
 }}
 
diff --git a/rc/modules/fzf-grep.kak b/rc/modules/fzf-grep.kak
index 936edef..e3a2de2 100644
--- a/rc/modules/fzf-grep.kak
+++ b/rc/modules/fzf-grep.kak
@@ -17,7 +17,7 @@ str fzf_grep_command 'grep'
 
 
 define-command -hidden fzf-grep %{ evaluate-commands %sh{
-    if [ -z "$(command -v $kak_opt_fzf_grep_command)" ]; then
+    if [ -z "$(command -v "${kak_opt_fzf_grep_command%% *}")" ]; then
         printf "%s\n" "echo -markup '{Information}''$kak_opt_fzf_grep_command'' is not installed. Falling back to ''grep'''"
         kak_opt_fzf_grep_command="grep"
     fi
@@ -35,13 +35,13 @@ define-command -hidden fzf-grep %{ evaluate-commands %sh{
     title="fzf grep"
     message="grep through contents of all files recursively.
 <ret>: open search result in new buffer.
-$kak_opt_fzf_window_map: open search result in new terminal"
-    [ ! -z "${kak_client_env_TMUX}" ] && tmux_keybindings="
-$kak_opt_fzf_horizontal_map: open search result in horizontal split
-$kak_opt_fzf_vertical_map: open search result in vertical split"
+${kak_opt_fzf_window_map:?}: open search result in new terminal"
+    [ -n "${kak_client_env_TMUX:-}" ] && tmux_keybindings="
+${kak_opt_fzf_horizontal_map:-}: open search result in horizontal split
+${kak_opt_fzf_vertical_map:-}: open search result in vertical split"
 
     printf "%s\n" "info -title '${title}' '${message}${tmux_keybindings}'"
-    [ ! -z "${kak_client_env_TMUX}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
+    [ -n "${kak_client_env_TMUX}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
     printf "%s\n" "fzf -kak-cmd %{evaluate-commands} -fzf-args %{--expect $kak_opt_fzf_window_map $additional_flags  --delimiter=':' -n'3..'} -items-cmd %{$cmd} -filter %{sed -E 's/([^:]+):([^:]+):.*/edit -existing \1; execute-keys \2gvc/'}"
 }}
 
diff --git a/rc/modules/fzf-project.kak b/rc/modules/fzf-project.kak
index 4255eaa..377dea7 100644
--- a/rc/modules/fzf-project.kak
+++ b/rc/modules/fzf-project.kak
@@ -24,7 +24,7 @@ map global fzf-project -docstring "delete project from project list" 'd' '<esc>:
 map global fzf-project -docstring "rename project" 'r' '<esc>: fzf-rename-project<ret>'
 
 define-command -hidden fzf-project %{ evaluate-commands %sh{
-    if [ -s ${kak_opt_fzf_project_file} ]; then
+    if [ -s "${kak_opt_fzf_project_file:-}" ]; then
         printf '%s\n' "info -title %{fzf open project} %{Change the server's working directory to selected project}"
         printf "%s\n" "fzf -kak-cmd change-directory -items-cmd %{cat ${kak_opt_fzf_project_file}} -fzf-args %{--reverse --delimiter=':' -n'1'} -post-action fzf-file -filter %{sed 's/.*:  //'}"
     else
@@ -33,12 +33,12 @@ define-command -hidden fzf-project %{ evaluate-commands %sh{
 }}
 
 define-command -hidden fzf-save-path-as-project %{ prompt -shell-script-candidates %{printf "%s\n" "${PWD##*/}"} "Project's name: " %{ evaluate-commands %sh{
-    if [ -n "${kak_text}" ]; then
+    if [ -n "${kak_text:-}" ]; then
         mkdir -p "${kak_opt_fzf_project_file%/*}"
-        exists=$(grep "${kak_text}:  " ${kak_opt_fzf_project_file})
+        exists=$(grep "${kak_text}:  " "${kak_opt_fzf_project_file:-}")
         if [ -z "${exists}" ]; then
-            [ "${kak_opt_fzf_project_use_tilda}" = "false" ] && project_path=$(pwd) || project_path=$(pwd | perl -pe "s(${HOME})(~)")
-            printf "%s:  %s\n" "${kak_text}" "${project_path}" >> ${kak_opt_fzf_project_file}
+            [ "${kak_opt_fzf_project_use_tilda:-true}" = "false" ] && project_path=$(pwd) || project_path=$(pwd | perl -pe "s(${HOME})(~)")
+            printf "%s:  %s\n" "${kak_text}" "${project_path}" >> "${kak_opt_fzf_project_file}"
             printf "%s\n" "echo -markup %{{Information}saved '$(pwd)' project as '${kak_text}'}"
         else
             printf "%s\n" "fzf-project-confirm-impl %{Project '${kak_text}' exists. Update? (y/N): } %{fzf-update-project-path-impl %{${kak_text}} %{${PWD}}} %{Project '${kak_text}' updated} %{Project '${kak_text}' kept}"
@@ -65,11 +65,11 @@ define-command -hidden fzf-save-path-as-project-no-prompt %{ evaluate-commands %
         esac
         printf "%s\n" "${base}"
     }
-    project_name=$(base ${PWD})
-    exists=$(grep "${project_name}:  " ${kak_opt_fzf_project_file})
+    project_name=$(base "${PWD}")
+    exists=$(grep "${project_name}:  " "${kak_opt_fzf_project_file}")
     if [ -z "${exists}" ]; then
-        [ "${kak_opt_fzf_project_use_tilda}" = "false" ] && project_path=$(pwd) || project_path=$(pwd | perl -pe "s(${HOME})(~)")
-        printf "%s:  %s\n" "${project_name}" "${project_path}" >> ${kak_opt_fzf_project_file}
+        [ "${kak_opt_fzf_project_use_tilda:-true}" = "false" ] && project_path=$(pwd) || project_path=$(pwd | perl -pe "s(${HOME})(~)")
+        printf "%s:  %s\n" "${project_name}" "${project_path}" >> "${kak_opt_fzf_project_file}"
         printf "%s\n" "echo -markup %{{Information}saved '$(pwd)' project as '${project_name}'}"
     else
         printf "%s\n" "fzf-project-confirm-impl %{Project '${project_name}' exists. Update? (y/N): } %{fzf-update-project-path-impl %{${project_name}} %{${PWD}}} %{${project_name}} %{Project '${project_name}' updated} %{Project '${project_name}' kept}"
@@ -103,11 +103,11 @@ fzf-add-project -file-completion -params 1..2 %{ evaluate-commands %sh{
     mkdir -p "${kak_opt_fzf_project_file%/*}"
     project_path="$1"
     project_name="$2"
-    [ -z "${project_name}" ] && project_name=$(base ${project_path})
-    exists=$(grep "${project_name}:  " ${kak_opt_fzf_project_file})
+    [ -z "${project_name}" ] && project_name=$(base "${project_path}")
+    exists=$(grep "${project_name}:  " "${kak_opt_fzf_project_file}")
     if [ -z "${exists}" ] || [ "${force}" = "true" ]; then
-        [ "${kak_opt_fzf_project_use_tilda}" = "false" ] || project_path=$(printf "%s\n" ${project_path} | perl -pe "s(${HOME})(~)")
-        printf "%s:  %s\n" "${project_name}" "${project_path}" >> ${kak_opt_fzf_project_file}
+        [ "${kak_opt_fzf_project_use_tilda:-true}" = "false" ] || project_path=$(printf "%s\n" "${project_path}" | perl -pe "s(${HOME})(~)")
+        printf "%s:  %s\n" "${project_name}" "${project_path}" >> "${kak_opt_fzf_project_file}"
         printf "%s\n" "echo -markup %{{Information}saved '${project_path}' project as '${project_name}'}"
     else
         printf "%s\n" "fzf-project-confirm-impl %{Project '${project_name}' exists. Update? (y/N): } %{fzf-update-project-path-impl %{${project_name}} %{${project_path}}} %{Project '${project_name}' updated} %{Project '${project_name}' kept}"
@@ -119,7 +119,7 @@ define-command -docstring \
 -hidden fzf-project-confirm-impl -params 2..4 %{
     prompt -shell-script-candidates %{printf "%s\n%s\n" "y" "n"} "%arg{1}" %{ evaluate-commands %sh{
         shift; function_to_call=$1; success_message=$2;  fail_message=$3
-        choice=$(printf "%s" "${kak_text}" | perl -pe "s/y(es)?.*//i") # case isensetive lookup for yes answer
+        choice=$(printf "%s" "${kak_text:-}" | perl -pe "s/y(es)?.*//i") # case isensetive lookup for yes answer
         if [ -z "${choice}" ]; then
             printf "%s\n" "${function_to_call}"
             [ -n "${success_message}" ] && printf "%s\n" "echo -markup %{{Information}${success_message}}"
diff --git a/rc/modules/fzf-search.kak b/rc/modules/fzf-search.kak
index 5ce23b2..ad52bb7 100644
--- a/rc/modules/fzf-search.kak
+++ b/rc/modules/fzf-search.kak
@@ -12,7 +12,7 @@ define-command -hidden fzf-buffer-search %{ evaluate-commands %sh{
     title="fzf buffer search"
     message="Search buffer with fzf, and jump to result location"
     printf "%s\n" "info -title '$title' '$message'"
-    buffer_content="$(mktemp ${TMPDIR:-/tmp}/fzf-buff-${kak_buffile##*/}.XXXXXX)"
+    buffer_content="$(mktemp "${TMPDIR:-/tmp}"/fzf-buff-"${kak_buffile##*/}".XXXXXX)"
     printf "%s\n" "execute-keys -draft %{%<a-|>cat<space>><space>$buffer_content<ret>;}"
     printf "%s\n" "fzf -kak-cmd %{execute-keys} -items-cmd %{(nl -b a -n ln $buffer_content; rm $buffer_content)} -fzf-args %{--reverse} -filter %{cut -f 1} -post-action %{execute-keys gx}"
 }}
diff --git a/rc/modules/fzf-vcs.kak b/rc/modules/fzf-vcs.kak
index 242413f..21a5085 100644
--- a/rc/modules/fzf-vcs.kak
+++ b/rc/modules/fzf-vcs.kak
@@ -33,17 +33,17 @@ bzr status"
     IFS='
 '
     for cmd in $commands; do
-        eval $cmd >/dev/null 2>&1
+        eval "$cmd" >/dev/null 2>&1
         res=$?
         if [ "$res"  = "0" ]; then
             vcs=$(printf "%s\n" "$cmd" | awk '{print $1}')
             title="fzf $vcs"
-            [ ! -z "${kak_client_env_TMUX}" ] && additional_keybindings="
-$kak_opt_fzf_horizontal_map: open file in horizontal split
-$kak_opt_fzf_vertical_map: open file in vertical split"
+            [ -n "${kak_client_env_TMUX:-}" ] && additional_keybindings="
+${kak_opt_fzf_horizontal_map:-}: open file in horizontal split
+${kak_opt_fzf_vertical_map:-}: open file in vertical split"
             message="Open single or multiple files from git tree.
 <ret>: open file in new buffer.
-$kak_opt_fzf_window_map: open file in new terminal $additional_keybindings"
+${kak_opt_fzf_window_map:?}: open file in new terminal $additional_keybindings"
             printf "%s\n" "info -title %{$title} %{$message}"
             printf "%s\n" "fzf-$vcs"
             exit
diff --git a/rc/modules/sk-grep.kak b/rc/modules/sk-grep.kak
index 72a4dcd..3e541ab 100644
--- a/rc/modules/sk-grep.kak
+++ b/rc/modules/sk-grep.kak
@@ -29,14 +29,14 @@ define-command -hidden fzf-sk-grep %{ evaluate-commands %sh{
     title="skim interactive grep"
     message="Interactively grep pattern from current directory
 <ret>: open search result in new buffer.
-$kak_opt_fzf_window_map: open search result in new terminal"
-    [ ! -z "${kak_client_env_TMUX}" ] && tmux_keybindings="
-$kak_opt_fzf_horizontal_map: open search result in horizontal split
-$kak_opt_fzf_vertical_map: open search result in vertical split"
+${kak_opt_fzf_window_map:?}: open search result in new terminal"
+    [ -n "${kak_client_env_TMUX:-}" ] && tmux_keybindings="
+${kak_opt_fzf_horizontal_map:-}: open search result in horizontal split
+${kak_opt_fzf_vertical_map:-}: open search result in vertical split"
 
     printf "%s\n" "info -title '${title}' '${message}${tmux_keybindings}'"
-    [ ! -z "${kak_client_env_TMUX}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
-    printf "%s\n" "fzf -kak-cmd %{fzf-sk-grep-handler} -fzf-impl %{sk --ansi -m -i -c '$kak_opt_fzf_sk_grep_command {}'} -fzf-args %{--expect $kak_opt_fzf_window_map $additional_flags} -multiple-cmd %{fzf-sk-populate-grep} -post-action %{buffer %opt{fzf_sk_first_file}}"
+    [ -n "${kak_client_env_TMUX}" ] && additional_flags="--expect $kak_opt_fzf_vertical_map --expect $kak_opt_fzf_horizontal_map"
+    printf "%s\n" "fzf -kak-cmd %{fzf-sk-grep-handler} -fzf-impl %{sk --ansi -m -i -c '${kak_opt_fzf_sk_grep_command:-} {}'} -fzf-args %{--expect $kak_opt_fzf_window_map $additional_flags} -multiple-cmd %{fzf-sk-populate-grep} -post-action %{buffer %opt{fzf_sk_first_file}}"
 }}
 
 define-command -hidden fzf-sk-grep-handler -params 1 %{