diff --git a/apps/docker-arm.sh b/apps/docker-arm.sh
index 432dc83..58e8ce8 100755
--- a/apps/docker-arm.sh
+++ b/apps/docker-arm.sh
@@ -1,7 +1,8 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+set -e
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 
 # let docker be able to build arm image on x86
diff --git a/apps/docker.sh b/apps/docker.sh
index 2049d80..461b28c 100755
--- a/apps/docker.sh
+++ b/apps/docker.sh
@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 
 # install docker
@@ -10,7 +10,7 @@ case "$PM" in
         # snap docker will intefere native docker.io, must be dealt with
         sudo snap remove --purge docker
         sudo apt install -y docker.io docker-compose
-        ! which pip3 && $ROOT/python/install.sh
+        ! command -v pip3 && "$ROOT/python/install.sh"
         sudo pip3 install docker-compose
         ;;
     pacman)
@@ -24,18 +24,18 @@ sudo systemctl start docker
 
 
 # configuration
-sudo usermod -aG docker $USER
+sudo usermod -aG docker "$USER"
 
 # completion
 case "$DEFAULT_SHELL" in
     $FISH)
-        curl -sLo $HOME/.config/fish/completions/docker.fish --create-dirs \
+        curl -sLo "$HOME/.config/fish/completions/docker.fish" --create-dirs \
             'https://github.com/docker/cli/raw/master/contrib/completion/fish/docker.fish'
         ;;
 esac
 
 # set mirror
-if in-china && [[ -d /etc/docker ]]; then
+if in_china && [ -d /etc/docker ]; then
     if [ -f /etc/docker/daemon.json ]; then
         # backup
         [ ! -f /etc/docker/daemon.bak.json ] && \
@@ -43,7 +43,7 @@ if in-china && [[ -d /etc/docker ]]; then
         # read
         dj=$(cat /etc/docker/daemon.json)
     fi
-    [[ -z $dj ]] && dj='{}'
+    [ -z "$dj" ] && dj='{}'
     echo $dj | jq '. + {"registry-mirrors": ["https://izuhlbap.mirror.aliyuncs.com"]}' | \
         sudo tee /etc/docker/daemon.json
     sudo systemctl restart docker
diff --git a/apps/install.sh b/apps/install.sh
index 3ff777a..81a3202 100755
--- a/apps/install.sh
+++ b/apps/install.sh
@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 
 # install office utilities
@@ -28,4 +28,4 @@ case "$PM" in
 esac
 
 # symlink configuration
-lnsf $DIR/config/zathura/zathurarc $XDG_CONFIG_HOME/zathura/zathurarc
+lnsf "$DIR/config/zathura/zathurarc" "$XDG_CONFIG_HOME/zathura/zathurarc"
diff --git a/apps/k8s.sh b/apps/k8s.sh
index 27c7a3e..ad837cb 100755
--- a/apps/k8s.sh
+++ b/apps/k8s.sh
@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 
 # install docker
@@ -17,8 +17,8 @@ esac
 # completion for fish
 case "$DEFAULT_SHELL" in
     "$FISH")
-        [[ ! -f $HOME/.config/fish/completions/docker.fish ]] && \
-            curl -Lo $HOME/.config/fish/completions/docker.fish --create-dirs \
+        [ ! -f "$HOME/.config/fish/completions/docker.fish" ] && \
+            curl -Lo "$HOME/.config/fish/completions/docker.fish" --create-dirs \
             'https://github.com/docker/cli/raw/master/contrib/completion/fish/docker.fish'
         fish -c "fisher add evanlucas/fish-kubectl-completions"
         ;;
diff --git a/apps/keepassxc.sh b/apps/keepassxc.sh
index c87d35d..9ba109e 100755
--- a/apps/keepassxc.sh
+++ b/apps/keepassxc.sh
@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 
 # install nextcloud
diff --git a/apps/nextcloud.sh b/apps/nextcloud.sh
index 49cde37..d49175d 100755
--- a/apps/nextcloud.sh
+++ b/apps/nextcloud.sh
@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 
 # install nextcloud
diff --git a/autologin/install.sh b/autologin/install.sh
index 01d73b4..1ca1209 100755
--- a/autologin/install.sh
+++ b/autologin/install.sh
@@ -1,13 +1,14 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
-read -p 'Please enter autologin username (empty to skip): ' username
+echo 'Please enter autologin username (empty to skip): '
+read -r username
 if [  -z "$username" ]; then
     echo skip autologin setup
 else
     sudo mkdir -p /etc/systemd/system/getty@tty1.service.d
-    sed -r "s/USERNAME/$username/g" $DIR/systemd/getty1-override.conf | \
+    sed -r "s/USERNAME/$username/g" "$DIR/systemd/getty1-override.conf" | \
         sudo tee /etc/systemd/system/getty@tty1.service.d/override.conf
 fi
diff --git a/deeplearning/install.sh b/deeplearning/install.sh
index ca5db8d..9dae283 100755
--- a/deeplearning/install.sh
+++ b/deeplearning/install.sh
@@ -1,18 +1,18 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 
-$ROOT/python/install.sh
+"$ROOT/python/install.sh"
 
 # install deep learning tools
 case "$PM" in
     apt)
         # cuda
-        source /etc/lsb-release
+        . /etc/lsb-release
         if [ "$DISTRIB_RELEASE" = "18.04" ] && [ "$(uname -m)" = 'x86_64' ]; then
-            sudo apt install linux-headers-$(uname -r)
+            sudo apt install "linux-headers-$(uname -r)"
             wget https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/cuda-ubuntu1804.pin
             sudo mv cuda-ubuntu1804.pin /etc/apt/preferences.d/cuda-repository-pin-600
             sudo apt-key adv --fetch-keys \
@@ -24,20 +24,20 @@ case "$PM" in
             sudo apt install nvidia-cuda-toolkit
         else
             echo 'Unsupported release'
-            exit -1
+            exit 1
         fi
 
         # nvidia docker
-        distribution=$(. /etc/os-release;echo $ID$VERSION_ID)
+        distribution="$ID$VERSION_ID"
         curl -s -L https://nvidia.github.io/nvidia-docker/gpgkey | sudo apt-key add -
-        curl -s -L https://nvidia.github.io/nvidia-docker/$distribution/nvidia-docker.list | \
+        curl -s -L "https://nvidia.github.io/nvidia-docker/$distribution/nvidia-docker.list" | \
             sudo tee /etc/apt/sources.list.d/nvidia-docker.list
         sudo apt update
         sudo apt install -y nvidia-docker2
         ;;
     pacman)
         echo TODO
-        exit -1
+        exit 1
         ;;
 esac
 
diff --git a/dunst/install.sh b/dunst/install.sh
index fc672b1..30378b4 100755
--- a/dunst/install.sh
+++ b/dunst/install.sh
@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 # install nvim
 case "$PM" in
@@ -14,5 +14,5 @@ case "$PM" in
 esac
 
 # symlink configuration
-lnsf $DIR/config/dunstrc $XDG_CONFIG_HOME/dunst/dunstrc
-lnsf $DIR/config/launch.sh $XDG_CONFIG_HOME/dunst/launch.sh
+lnsf "$DIR/config/dunstrc" "$XDG_CONFIG_HOME/dunst/dunstrc"
+lnsf "$DIR/config/launch.sh" "$XDG_CONFIG_HOME/dunst/launch.sh"
diff --git a/env.sh b/env.sh
index 0ce44fd..ab013a2 100755
--- a/env.sh
+++ b/env.sh
@@ -1,61 +1,56 @@
-#!/bin/bash
+#!/bin/sh
 
 set -e
-ROOT=$(readlink -f $(dirname "${BASH_SOURCE[0]}"))
+ROOT=$(readlink -f "$(dirname "$0")")
 PM=n/a
-DEFAULT_SHELL=$(getent passwd $USER | cut -d: -f7)
-FISH=$(which fish)
 XDG_CONFIG_HOME=${XDG_CONFIG_HOME-"$HOME/.config"}
+echo "dotfiles path: $ROOT"
 
-if which pacman > /dev/null; then
+if command -v pacman > /dev/null; then
     PM=pacman
-elif which apt > /dev/null; then
+elif command -v apt > /dev/null; then
     PM=apt
 fi
 
 if [ "$PM" = "n/a" ]; then
     echo "Unsupported Package Manager"
-    exit -1
+    exit 1
 fi
 
-in-china () {
+in_china () {
     if [ -z "$IS_CHINA" ]; then
         IS_CHINA=no
         if curl -q myip.ipip.net | grep '中国' > /dev/null; then
             IS_CHINA=yes
         fi
     fi
-    [ "$IS_CHINA" = "no" ] && return -1
+    [ "$IS_CHINA" = "no" ] && return 1
     return 0
 }
 
 lnsf () {
-    [ "$#" -ne 2 ] && echo "lnsf <target> <symlink>" && return -1
-    local TARGET=$(readlink -f $1)
-    local SYMLNK=$2
-    [ -z "$TARGET" ] && echo "$1 not exists" && return -1
-    local SYMDIR=$(dirname $SYMLNK)
-    if [[ -n $SYMDIR && -L $SYMDIR ]]; then
-        rm -rf $SYMDIR
+    [ "$#" -ne 2 ] && echo "lnsf <target> <symlink>" && return 1
+    TARGET=$(readlink -f "$1")
+    SYMLNK=$2
+    [ -z "$TARGET" ] && echo "$1 not exists" && return 1
+    SYMDIR=$(dirname "$SYMLNK")
+    if [ -n "$SYMDIR" && -L "$SYMDIR" ]; then
+        rm -rf "$SYMDIR"
     fi
-    mkdir -p $SYMDIR
-    [ ! -L $SYMLNK ] && rm -rf $SYMLNK
-    ln -sf $TARGET $SYMLNK
+    mkdir -p "$SYMDIR"
+    [ ! -L "$SYMLNK" ] && rm -rf "$SYMLNK"
+    ln -sf "$TARGET" "$SYMLNK"
 }
 
-fish-is-default-shell () {
-    [ "$DEFAULT_SHELL" = "$FISH" ]
-}
-
-has-bluetooth () {
+has_bluetooth () {
     dmesg | grep -i bluetooth
 }
 
 eqv () {
-    local VERSION_PATH=$1
-    local VERSION=$2
-    [ ! -f $VERSION_PATH ] && return -1
-    local VERSION2=$(cat "$VERSION_PATH")
+    VERSION_PATH=$1
+    VERSION=$2
+    [ ! -f "$VERSION_PATH" ] && return 1
+    VERSION2="$(cat "$VERSION_PATH")"
     [ "$VERSION" = "$VERSION2" ]
 }
 
@@ -78,7 +73,7 @@ case "$PM" in
             curl wget \
             man sudo
         # install yay
-        if ! which yay; then
+        if ! command -v yay; then
             git clone --depth 1 https://aur.archlinux.org/yay.git /tmp/yay
             cd /tmp/yay
             makepkg -si
diff --git a/fish/install.sh b/fish/install.sh
index c257e0b..1fd0694 100755
--- a/fish/install.sh
+++ b/fish/install.sh
@@ -1,25 +1,23 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 # install fish shell
 echo Installing fish shell
 case "$PM" in
     apt)
-        ! which pip3 && $ROOT/python/install.sh
+        ! command -v pip3 && "$ROOT/python/install.sh"
         sudo add-apt-repository ppa:fish-shell/release-3 -y
         sudo apt update
         sudo apt install fish libnotify-bin xdotool silversearcher-ag dash -y
-        if apt show fzf &>/dev/null; then
-            sudo apt install fzf
-        elif ! which fzf &>/dev/null; then
+        if apt show fzf 2>/dev/null; then
+            sudo apt install -y fzf
             git clone --depth 1 https://github.com/junegunn/fzf.git ~/.fzf
             ~/.fzf/install
         fi
         ;;
     pacman)
-        ! which pip && $ROOT/python/install.sh
         sudo pacman -S --needed --needed fish xdotool fzf the_silver_searcher dash
         # prevent bash upgradation relink /bin/sh
         sudo mkdir -p /etc/pacman.d/hooks
@@ -40,18 +38,18 @@ case "$PM" in
 esac
 
 # use dash as default shell because it much faster and will be used  vim-fugitive,
-# which leads to a much faster responsive speed
+# leads to a much faster responsive speed
 sudo /usr/bin/ln -sfT dash /usr/bin/sh
 chsh -s /bin/sh
 
 
 # symlink config
-[ -L $XDG_CONFIG_HOME/fish ] && rm -rf $XDG_CONFIG_HOME/fish
+[ -L "$XDG_CONFIG_HOME/fish" ] && rm -rf "$XDG_CONFIG_HOME/fish"
 
-lnsf $DIR/config/config.fish $XDG_CONFIG_HOME/fish/config.fish
-lnsf $DIR/config/functions/fish_prompt.fish $XDG_CONFIG_HOME/fish/functions/fish_prompt.fish
-lnsf $DIR/config/functions/fish_right_prompt.fish $XDG_CONFIG_HOME/fish/functions/fish_right_prompt.fish
-lnsf $DIR/config/functions/fisher.fish $XDG_CONFIG_HOME/fish/functions/fisher.fish
+lnsf "$DIR/config/config.fish" "$XDG_CONFIG_HOME/fish/config.fish"
+lnsf "$DIR/config/functions/fish_prompt.fish" "$XDG_CONFIG_HOME/fish/functions/fish_prompt.fish"
+lnsf "$DIR/config/functions/fish_right_prompt.fish" "$XDG_CONFIG_HOME/fish/functions/fish_right_prompt.fish"
+lnsf "$DIR/config/functions/fisher.fish" "$XDG_CONFIG_HOME/fish/functions/fisher.fish"
 
 # install plugins
 fish -c "fisher add jethrokuan/fzf"
diff --git a/gui/install.sh b/gui/install.sh
index e830294..6feee08 100755
--- a/gui/install.sh
+++ b/gui/install.sh
@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 # install basic gui stuff, including fonts/system utilties/keyring etc
 case "$PM" in
@@ -18,7 +18,7 @@ case "$PM" in
         sudo apt install \
             network-manager network-manager-gnome
         # bluetooth
-        if has-bluetooth; then
+        if has_bluetooth; then
             sudo apt install \
                 bluez bluez-tools blueman pulseaudio-module-bluetooth
             sudo systemctl enable bluetooth
@@ -41,10 +41,9 @@ case "$PM" in
         # https://code.google.com/p/chromium/issues/detail?id=233851
         # use debian package instead
         DEB_PKG_NAME=fonts-wqy-microhei_0.2.0-beta-3_all.deb
-        PAC_PKG_NAME=fonts-wqy-microhei_0.2.0-beta-3_all.pkg
-        [[ ! -f /tmp/$DEB_PKG_NAME ]] && \
+        [ ! -f "/tmp/$DEB_PKG_NAME" ] && \
             wget http://mirrors.163.com/debian/pool/main/f/fonts-wqy-microhei/$DEB_PKG_NAME -O /tmp/$DEB_PKG_NAME
-        ar p /tmp/$DEB_PKG_NAME data.tar.xz | sudo tar Jxv -C /
+        ar p "/tmp/$DEB_PKG_NAME" data.tar.xz | sudo tar Jxv -C /
         # install symbola for plain emojis(no-color) for st
         ! fc-list | grep -qi symbola && yay -S --needed ttf-symbola-free
         # clipboard
@@ -57,7 +56,7 @@ case "$PM" in
         sudo pacman -S --needed \
             networkmanager network-manager-applet
         # bluetooth
-        if has-bluetooth; then
+        if has_bluetooth; then
             sudo pacman -S --needed \
                 bluez bluez-utils blueman pulseaudio-bluetooth xorg-xbacklight
             sudo systemctl enable bluetooth
@@ -73,7 +72,7 @@ esac
 
 
 # install hermit nerd font
-install-nerdfont () {
+install_nerdfont () {
     grep -F "$*" /usr/local/share/fonts/nerdfont && return
     ORIGIN_NAME=$1
     PATCHED_PAT=$2
@@ -81,22 +80,21 @@ install-nerdfont () {
     NAME=$ORIGIN_NAME-$VERSION.zip
     LOCAL_REPO_PATH=/tmp/nerd-font/$ORIGIN_NAME
     # shortcircuit if font already in system
-    fc-list | grep -F $0 | grep -i nerd && return
+    fc-list | grep -F "$PATCHED_PAT" | grep -i nerd && return
     # clone single branch from gitee
-    git clone --single-branch --branch $ORIGIN_NAME --depth 1 \
+    git clone --single-branch --branch "$ORIGIN_NAME" --depth 1 \
         https://gitee.com/klesh/nerd-fonts.git \
-        $LOCAL_REPO_PATH
-    sudo 7z x -x!'*Windows*' -aoa $LOCAL_REPO_PATH/$NAME -o/usr/local/share/fonts
+        "$LOCAL_REPO_PATH"
+    sudo 7z x -x!'*Windows*' -aoa "$LOCAL_REPO_PATH/$NAME" -o/usr/local/share/fonts
     sudo chmod +rx /usr/local/share/fonts
     echo "$*" | sudo tee -a /usr/local/share/fonts/nerdfont
-    echo $LOCAL_REPO_PATH
-    rm -rf $LOCAL_REPO_PATH
+    rm -rf "$LOCAL_REPO_PATH"
 }
 
-#install-nerdfont Hermit Hurmit v2.1.0
-install-nerdfont Agave agave v2.1.0
-#install-nerdfont CascadiaCode Caskaydia v2.1.0
-#install-nerdfont DaddyTimeMono DaddyTimeMono v2.1.0
+#install_nerdfont Hermit Hurmit v2.1.0
+install_nerdfont Agave agave v2.1.0
+#install_nerdfont CascadiaCode Caskaydia v2.1.0
+#install_nerdfont DaddyTimeMono DaddyTimeMono v2.1.0
 
 # start network
 sudo systemctl enable NetworkManager
@@ -106,5 +104,5 @@ sudo systemctl start NetworkManager
 sudo ln -sf /etc/fonts/conf.avail/70-no-bitmaps.conf /etc/fonts/conf.d
 sudo ln -sf /etc/fonts/conf.avail/10-sub-pixel-rgb.conf /etc/fonts/conf.d
 sudo ln -sf /etc/fonts/conf.avail/11-lcdfilter-default.conf /etc/fonts/conf.d
-sudo cp $DIR/freetype2.sh /etc/profile.d/freetype2.sh
-sudo cp $DIR/local.conf /etc/fonts/local.conf
+sudo cp "$DIR/freetype2.sh" "/etc/profile.d/freetype2.sh"
+sudo cp "$DIR/local.conf" "/etc/fonts/local.conf"
diff --git a/gui/sshd.sh b/gui/sshd.sh
index 14c3fce..f88b756 100755
--- a/gui/sshd.sh
+++ b/gui/sshd.sh
@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 # install sshd
 case "$PM" in
diff --git a/gui/theme.sh b/gui/theme.sh
index 9afd86b..0d96a00 100755
--- a/gui/theme.sh
+++ b/gui/theme.sh
@@ -1,7 +1,8 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+set -e
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 # for better looking
 case "$PM" in
diff --git a/kvm/install.sh b/kvm/install.sh
index fbdd9af..2ece8e7 100755
--- a/kvm/install.sh
+++ b/kvm/install.sh
@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 # tips
 # 1. to relocate default pool
@@ -26,4 +26,4 @@ case "$PM" in
 esac
 
 # configuration
-sudo usermod -aG libvirt $USER
+sudo usermod -aG libvirt "$USER"
diff --git a/nodejs/install.sh b/nodejs/install.sh
index 5781efa..0994c5d 100755
--- a/nodejs/install.sh
+++ b/nodejs/install.sh
@@ -1,21 +1,21 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 # install specific version
-if [[ -n $1 ]]; then
-    if which node &>/dev/null && [[ "$1" != "$(node -v)" ]]; then
+if [ -n "$1" ]; then
+    if command -v node 1>/dev/null 2>&1 && [ "$1" != "$(node -v)" ]; then
         NODE_URL=https://nodejs.org/dist
-        in-china && NODE_URL=https://npm.taobao.org/mirrors/node
-        if [[ $1 == 'ls' ]]; then
+        in_china && NODE_URL=https://npm.taobao.org/mirrors/node
+        if [ "$1" = 'ls' ]; then
             curl -s $NODE_URL/index.json |  jq '.[] | "\(.version) \(if .lts then "(lts)" else "" end)"' -r | less
             exit
         else
             FN=node-$1-linux-x64.tar.gz
-            wget -O /tmp/$FN $NODE_URL/$1/$FN
-            sudo tar zxvf /tmp/$FN --strip 1 -C /usr/local/
-            rm /tmp/$FN
+            wget -O "/tmp/$FN" "$NODE_URL/$1/$FN"
+            sudo tar zxvf "/tmp/$FN" --strip 1 -C /usr/local/
+            rm "/tmp/$FN"
         fi
     fi
 else
@@ -32,7 +32,7 @@ fi
 
 
 # install nvm
-if which fish 2>/dev/null; then
+if command -v fish 2>/dev/null; then
     fish -c "fisher add jorgebucaran/nvm.fish"
 else
     curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.35.3/install.sh | bash
@@ -40,7 +40,7 @@ fi
 
 
 # config mirrors for CHINA
-if in-china; then
+if in_china; then
     sudo npm install cnpm -g --registry=https://r.npm.taobao.org
     yarnpkg config set registry https://registry.npm.taobao.org --global  && \
     yarnpkg config set disturl https://npm.taobao.org/dist --global && \
diff --git a/nvim/config/coc-settings.json b/nvim/config/coc-settings.json
index 9912940..36d9896 100644
--- a/nvim/config/coc-settings.json
+++ b/nvim/config/coc-settings.json
@@ -2,5 +2,8 @@
     "npm.binPath": "yarnpkg",
     "python.linting.enable": true,
     "python.linting.flake8Enabled": true,
-    "python.linting.pylintEnabled": false
+    "python.linting.pylintEnabled": false,
+    "diagnostic-languageserver.filetypes": {
+        "sh": ["shellcheck", "-e", "SC1090"]
+    }
 }
diff --git a/nvim/install.sh b/nvim/install.sh
index 17fba2c..908803f 100755
--- a/nvim/install.sh
+++ b/nvim/install.sh
@@ -1,10 +1,10 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 # check dependencies
-! which yarnpkg && $ROOT/nodejs/install.sh
+! command -v yarnpkg && "$ROOT/nodejs/install.sh"
 
 # install nvim
 case "$PM" in
@@ -19,6 +19,6 @@ case "$PM" in
 esac
 
 # symlink configuration
-lnsf $DIR/config/init.vim $XDG_CONFIG_HOME/nvim/init.vim
-lnsf $DIR/config/coc-settings.json $XDG_CONFIG_HOME/nvim/coc-settings.json
-lnsf $DIR/config/init.vim ~/.vimrc
+lnsf "$DIR/config/init.vim" "$XDG_CONFIG_HOME/nvim/init.vim"
+lnsf "$DIR/config/coc-settings.json" "$XDG_CONFIG_HOME/nvim/coc-settings.json"
+lnsf "$DIR/config/init.vim" ~/.vimrc
diff --git a/optim/mirrors.sh b/optim/mirrors.sh
index 427e8fc..bb116ae 100755
--- a/optim/mirrors.sh
+++ b/optim/mirrors.sh
@@ -1,10 +1,10 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 
-! in-china && echo 'Skip mirrors configuration' && exit
+! in_china && echo 'Skip mirrors configuration' && exit
 
 # setup package mirror for CHINA
 case "$PM" in
@@ -18,7 +18,7 @@ case "$PM" in
         ;;
     pacman)
         echo TODO
-        exit -1
+        exit 1
         ;;
 esac
 
diff --git a/optim/ubuntu-desk-boot.sh b/optim/ubuntu-desk-boot.sh
index ca5cc53..61156e8 100755
--- a/optim/ubuntu-desk-boot.sh
+++ b/optim/ubuntu-desk-boot.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 
 sudo systemctl disable systemd-networkd-wait-online
diff --git a/picom/install.sh b/picom/install.sh
index efe47ec..1b2881a 100755
--- a/picom/install.sh
+++ b/picom/install.sh
@@ -1,16 +1,15 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
-
-PICOM_VER=v8.1
+set -e
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 
 # install ranger
 case "$PM" in
     apt)
         # install build tools
-        ! which pip3 && $ROOT/python/install.sh
+        ! command -v pip3 && "$ROOT/python/install.sh"
         sudo pip3 install meson
         # install dependencies
         sudo apt install -y ninja-build libxext-dev libxcb1-dev libxcb-damage0-dev libxcb-xfixes0-dev libxcb-shape0-dev libxcb-render-util0-dev libxcb-render0-dev libxcb-randr0-dev libxcb-composite0-dev libxcb-image0-dev libxcb-present-dev libxcb-xinerama0-dev libxcb-glx0-dev libpixman-1-dev libdbus-1-dev libconfig-dev libgl1-mesa-dev  libpcre3-dev  libevdev-dev uthash-dev libev-dev libx11-xcb-dev
@@ -29,16 +28,16 @@ if [ "$VERSION" = "next" ] || ! eqv "$VERSION_PATH" "$VERSION"; then
         curl "https://github.com/yshui/picom/archive/$VERSION.zip" -Lo /tmp/picom-$VERSION.zip
     unzip /tmp/picom-$VERSION.zip -d /tmp
     FD=$(unzip -l /tmp/picom-$VERSION.zip | awk 'NR==5{print $4}')
-    pushd /tmp/$FD
+    cd "/tmp/$FD"
     meson --buildtype=release . build
     sudo ninja -C build install
-    popd
-    mkdir -p $(dirname $VERSION_PATH)
+    cd -
+    mkdir -p "$(dirname "$VERSION_PATH")"
     echo "$VERSION" > "$VERSION_PATH"
     sudo rm -rf /tmp/picom-$VERSION*
 fi
 
 # configuration
-lnsf $DIR/config/launch.sh $XDG_CONFIG_HOME/picom/launch.sh
-lnsf $DIR/config/toggle.sh $XDG_CONFIG_HOME/picom/toggle.sh
-lnsf $DIR/config/picom.conf $XDG_CONFIG_HOME/picom/picom.conf
+lnsf "$DIR/config/launch.sh" "$XDG_CONFIG_HOME/picom/launch.sh"
+lnsf "$DIR/config/toggle.sh" "$XDG_CONFIG_HOME/picom/toggle.sh"
+lnsf "$DIR/config/picom.conf" "$XDG_CONFIG_HOME/picom/picom.conf"
diff --git a/player/install.sh b/player/install.sh
index 4f4c752..80a80c0 100755
--- a/player/install.sh
+++ b/player/install.sh
@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 
 # install music and video player
@@ -15,16 +15,16 @@ case "$PM" in
 esac
 
 # symlink configuration
-lnsf $DIR/config/mpd/mpd.conf $XDG_CONFIG_HOME/mpd/mpd.conf
-lnsf $DIR/config/mpv/mpv.conf $XDG_CONFIG_HOME/mpv/mpv.conf
-lnsf $DIR/config/mpv/scripts/organize.lua $XDG_CONFIG_HOME/mpv/scripts/organize.lua
-lnsf $DIR/config/ncmpcpp/bindings $XDG_CONFIG_HOME/ncmpcpp/bindings
-lnsf $DIR/config/ncmpcpp/config $XDG_CONFIG_HOME/ncmpcpp/config
+lnsf "$DIR/config/mpd/mpd.conf" "$XDG_CONFIG_HOME/mpd/mpd.conf"
+lnsf "$DIR/config/mpv/mpv.conf" "$XDG_CONFIG_HOME/mpv/mpv.conf"
+lnsf "$DIR/config/mpv/scripts/organize.lua" "$XDG_CONFIG_HOME/mpv/scripts/organize.lua"
+lnsf "$DIR/config/ncmpcpp/bindings" "$XDG_CONFIG_HOME/ncmpcpp/bindings"
+lnsf "$DIR/config/ncmpcpp/config" "$XDG_CONFIG_HOME/ncmpcpp/config"
 
 # prevent system-wide mpd
 sudo systemctl disable mpd
 sudo systemctl stop mpd
-mkdir -p $HOME/.mpd/playlists
+mkdir -p "$HOME/.mpd/playlists"
 
 # enable for current user
 systemctl --user enable mpd
diff --git a/python/install.sh b/python/install.sh
index b34bb8d..c2907a4 100755
--- a/python/install.sh
+++ b/python/install.sh
@@ -1,14 +1,14 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 # config pip mirror for CHINA
-if in-china; then
-    lnsf $DIR/pip.conf ~/.pip/pip.conf
+if in_china; then
+    lnsf "$DIR/pip.conf" ~/.pip/pip.conf
     if sudo [ ! -f /root/.pip/pip.conf ]; then
         sudo mkdir -p /root/.pip
-        sudo cp $DIR/pip.conf /root/.pip/pip.conf
+        sudo cp "$DIR/pip.conf" /root/.pip/pip.conf
     fi
 fi
 
@@ -16,15 +16,15 @@ fi
 case "$PM" in
     apt)
         sudo apt install python3 python3-pip python-is-python3
-        which fish 2>/dev/null && sudo pip3 install virtualfish
+        command -v fish 2>/dev/null && sudo pip3 install virtualfish
         ;;
     pacman)
         sudo pacman -S --needed python python-pip
-        which fish 2>/dev/null && sudo pip install virtualfish
+        command -v fish 2>/dev/null && sudo pip install virtualfish
         ;;
 esac
 
 # enable auto_activation plugin for virtualfish
-which fish 2>/dev/null && fish -c "yes | vf install && vf addplugins auto_activation"
+command -v fish 2>/dev/null && fish -c "yes | vf install && vf addplugins auto_activation"
 
 
diff --git a/python/py3.sh b/python/py3.sh
index fb136f2..efb3173 100755
--- a/python/py3.sh
+++ b/python/py3.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 set -e
 
diff --git a/ranger/install.sh b/ranger/install.sh
index 415b0e4..3a1ae93 100755
--- a/ranger/install.sh
+++ b/ranger/install.sh
@@ -1,14 +1,14 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 # install ranger
 case "$PM" in
     apt)
         # atool/p7zip-full for archive previewing/extracting etc
         sudo apt install -y atool p7zip-full unrar highlight
-        ! which pip3 && $ROOT/python/install.sh
+        ! command -v pip3 && "$ROOT/python/install.sh"
         sudo pip3 install ranger-fm ueberzug
         ;;
     pacman)
@@ -18,9 +18,9 @@ case "$PM" in
 esac
 
 # linking configuration files
-lnsf $DIR/config/commands.py $XDG_CONFIG_HOME/ranger/commands.py
-lnsf $DIR/config/rc.conf $XDG_CONFIG_HOME/ranger/rc.conf
-lnsf $DIR/config/scope.sh $XDG_CONFIG_HOME/ranger/scope.sh
+lnsf "$DIR/config/commands.py" "$XDG_CONFIG_HOME/ranger/commands.py"
+lnsf "$DIR/config/rc.conf" "$XDG_CONFIG_HOME/ranger/rc.conf"
+lnsf "$DIR/config/scope.sh" "$XDG_CONFIG_HOME/ranger/scope.sh"
 
 # install devicons
 git clone --depth 1 https://github.com/alexanderjeurissen/ranger_devicons ~/.config/ranger/plugins/ranger_devicons
diff --git a/suckless/install.sh b/suckless/install.sh
index eba5ea2..583ea1f 100755
--- a/suckless/install.sh
+++ b/suckless/install.sh
@@ -1,12 +1,12 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
-$ROOT/fish/install.sh
-$ROOT/gui/install.sh
-$ROOT/picom/install.sh
-$ROOT/dunst/install.sh
+"$ROOT/fish/install.sh"
+"$ROOT/gui/install.sh"
+"$ROOT/picom/install.sh"
+"$ROOT/dunst/install.sh"
 
 # install dependencies
 case "$PM" in
@@ -86,8 +86,8 @@ EOT
 
 
 # config dwm
-[[ -L $XDG_CONFIG_HOME/dwm/autostart ]] && rm $XDG_CONFIG_HOME/dwm/autostart
-mkdir -p $XDG_CONFIG_HOME/dwm
-cp $DIR/config/dwm/autostart $XDG_CONFIG_HOME/dwm/autostart
-lnsf $DIR/config/dwm/statusbar $XDG_CONFIG_HOME/dwm/statusbar
-lnsf $DIR/config/autorandr/postswitch $XDG_CONFIG_HOME/autorandr/postswitch
+[ -L "$XDG_CONFIG_HOME/dwm/autostart" ] && rm "$XDG_CONFIG_HOME/dwm/autostart"
+mkdir -p "$XDG_CONFIG_HOME/dwm"
+cp "$DIR/config/dwm/autostart" "$XDG_CONFIG_HOME/dwm/autostart"
+lnsf "$DIR/config/dwm/statusbar" "$XDG_CONFIG_HOME/dwm/statusbar"
+lnsf "$DIR/config/autorandr/postswitch" "$XDG_CONFIG_HOME/autorandr/postswitch"
diff --git a/thunar/install.sh b/thunar/install.sh
index 3011994..132bed7 100755
--- a/thunar/install.sh
+++ b/thunar/install.sh
@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 # install ranger
 case "$PM" in
@@ -16,4 +16,4 @@ case "$PM" in
 esac
 
 # symlink configuration
-lnsf $DIR/Thunar/uca.xml $XDG_CONFIG_HOME/Thunar/uca.xml
+lnsf "$DIR/Thunar/uca.xml" "$XDG_CONFIG_HOME/Thunar/uca.xml"
diff --git a/tmux/install.sh b/tmux/install.sh
index ffb3f90..1364ef6 100755
--- a/tmux/install.sh
+++ b/tmux/install.sh
@@ -1,28 +1,29 @@
-#!/bin/bash
+#!/bin/sh
 
-DIR=$(readlink -f $(dirname $0))
-. $DIR/../env.sh
+set -e
+DIR=$(readlink -f "$(dirname "$0")")
+. "$DIR/../env.sh"
 
 TMUX_VER=3.1b
 
 # install ranger
 case "$PM" in
     apt)
-        if which tmux &>/dev/null && [ "$(tmux -V)" != "tmux $TMUX_VER" ]; then
+        if command -v tmux &>/dev/null && [ "$(tmux -V)" != "tmux $TMUX_VER" ]; then
             sudo apt install libevent-dev libncurses5-dev bison autoconf bc -y
             TMUX_SRC_URL=https://github.com/tmux/tmux/releases/download/$TMUX_VER/tmux-$TMUX_VER.tar.gz
-            if in-china; then
-                TMUX_SRC_URL=https://gitee.com/klesh/tmux/repository/archive/$TMUX_VER?format=tar.gz
+            if in_china; then
+                TMUX_SRC_URL="https://gitee.com/klesh/tmux/repository/archive/$TMUX_VER?format=tar.gz"
             fi
-            [ ! -f /tmp/tmux.tar.gz ] && curl -L $TMUX_SRC_URL -o /tmp/tmux.tar.gz
+            [ ! -f /tmp/tmux.tar.gz ] && curl -L "$TMUX_SRC_URL" -o /tmp/tmux.tar.gz
             rm -rf /tmp/tmux
             mkdir -p /tmp/tmux
             tar zxvf /tmp/tmux.tar.gz -C /tmp/tmux --strip 1
-            pushd /tmp/tmux
+            cd /tmp/tmux
             [ -f autogen.sh ] && sh autogen.sh
             ./configure && make
             sudo make install
-            popd
+            cd -
             rm -rf /tmp/tmux*
         fi
         ;;
@@ -32,6 +33,6 @@ case "$PM" in
 esac
 
 # symlink configuration
-lnsf $DIR/tmux.conf ~/.tmux.conf
-lnsf $DIR/config/tmux2.8.conf $XDG_CONFIG_HOME/tmux/tmux2.8.conf
-lnsf $DIR/config/tmux2.9.conf $XDG_CONFIG_HOME/tmux/tmux2.9.conf
+lnsf "$DIR/tmux.conf" ~/.tmux.conf
+lnsf "$DIR/config/tmux2.8.conf" "$XDG_CONFIG_HOME/tmux/tmux2.8.conf"
+lnsf "$DIR/config/tmux2.9.conf" "$XDG_CONFIG_HOME/tmux/tmux2.9.conf"