diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index e5936ba..5cbcfd7 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -45,7 +45,7 @@ repos:
     hooks:
       - id: check-mailmap
   - repo: https://github.com/adrienverge/yamllint
-    rev: v1.29.0
+    rev: v1.30.0
     hooks:
       - id: yamllint
   - repo: https://github.com/executablebooks/mdformat
diff --git a/bin/nix-env.jq b/bin/nix-env.jq
new file mode 100755
index 0000000..f27800e
--- /dev/null
+++ b/bin/nix-env.jq
@@ -0,0 +1,8 @@
+#!/usr/bin/env -S jq -rf
+.[] as $root | $root.meta | "# \(.name)
+<\(.homepage)> *\(.license.spdxId)*
+\(.description)
+
+\(.longDescription)
+\($root.outputs.out)
+\(.position)"
diff --git a/functions/helper.zsh b/functions/main.zsh
similarity index 92%
rename from functions/helper.zsh
rename to functions/main.zsh
index 3b10804..c76a9a2 100644
--- a/functions/helper.zsh
+++ b/functions/main.zsh
@@ -1,5 +1,6 @@
 # define some functions to avoid any error that these programs don't exist
 (($+commands[bat])) || bat() {cat}
+(($+commands[mdcat])) || mdcat() {bat}
 (($+commands[pygmentize])) || pygmentize() {cat}
 (($+commands[delta])) || delta() {cat}
 (($+commands[less])) || less() {ls -l}
@@ -13,3 +14,5 @@ touch ~/.gitmoji/gitmojis.json
 
 # dictionary $ZINIT cannot be passed
 PLUGINS_DIR=${ZINIT[PLUGINS_DIR]}
+
+. $src
diff --git a/fzf-tab-source.plugin.zsh b/fzf-tab-source.plugin.zsh
old mode 100644
new mode 100755
index 3cca45b..44f3c19
--- a/fzf-tab-source.plugin.zsh
+++ b/fzf-tab-source.plugin.zsh
@@ -21,7 +21,7 @@ for src in $dir/sources/*.zsh $sources; do
       break
     fi
   done < $src
-  zstyle $ctx fzf-preview ". $dir/functions/helper.zsh && . $src"
+  zstyle $ctx fzf-preview "src="\""$src"\"" . "\""$dir"\""/functions/main.zsh"
   flags=${arr[2]}
   if [[ -n $flags ]]; then
     zstyle $ctx fzf-flags $flags
diff --git a/sources/_complete.zsh b/sources/--complete.zsh
similarity index 81%
rename from sources/_complete.zsh
rename to sources/--complete.zsh
index acea466..e93421e 100644
--- a/sources/_complete.zsh
+++ b/sources/--complete.zsh
@@ -1,3 +1,3 @@
 # :fzf-tab:complete:*
 # `${realpath#--*=}` aims to handle `--long-option=/the/path/of/a/file`
-less ${realpath#--*=}
+less ${realpath#-*=}
diff --git a/sources/_user-expand.zsh b/sources/--user-expand.zsh
similarity index 100%
rename from sources/_user-expand.zsh
rename to sources/--user-expand.zsh
diff --git a/sources/checkmk.zsh b/sources/checkmk.zsh
new file mode 100644
index 0000000..9371e84
--- /dev/null
+++ b/sources/checkmk.zsh
@@ -0,0 +1,3 @@
+# :fzf-tab:complete:(\\|*/|)checkmk:
+[[ -f $realpath ]] && checkmk $realpath | bat --color=always -plc ||
+  less $realpath
diff --git a/sources/gcov.zsh b/sources/gcov.zsh
new file mode 100644
index 0000000..29b1f8d
--- /dev/null
+++ b/sources/gcov.zsh
@@ -0,0 +1,2 @@
+# :fzf-tab:complete:(\\|*/|)gcov:
+[[ -f $realpath ]] && gcov $realpath || less $realpath
diff --git a/sources/ifnames.zsh b/sources/ifnames.zsh
new file mode 100644
index 0000000..48bb32f
--- /dev/null
+++ b/sources/ifnames.zsh
@@ -0,0 +1,2 @@
+# :fzf-tab:complete:(\\|*/|)ifnames:
+[[ -f $realpath ]] && ifnames $realpath || less $realpath
diff --git a/sources/ninja.zsh b/sources/ninja.zsh
new file mode 100644
index 0000000..6bcd7de
--- /dev/null
+++ b/sources/ninja.zsh
@@ -0,0 +1,6 @@
+# :fzf-tab:complete:(\\|*/|)ninja:argument-rest
+case $group in
+targets)
+  ninja -n $word
+  ;;
+esac
diff --git a/sources/nix-env.zsh b/sources/nix-env.zsh
new file mode 100644
index 0000000..2304323
--- /dev/null
+++ b/sources/nix-env.zsh
@@ -0,0 +1,13 @@
+# :fzf-tab:complete:(\\|*/|)nix-env:*
+case $group in
+'Attribute path')
+  nix-env -qa --out-path --json --meta -A $ctxt[hpre]$word |
+    ${src:h:h}/bin/nix-env.jq | mdcat
+  ;;
+'Installed package'*)
+  nix-env -q --out-path --json --meta $word | ${src:h:h}/bin/nix-env.jq | mdcat
+  ;;
+'Local file')
+  less $realpath
+  ;;
+esac
diff --git a/sources/nix-hash.zsh b/sources/nix-hash.zsh
new file mode 100644
index 0000000..48bd73e
--- /dev/null
+++ b/sources/nix-hash.zsh
@@ -0,0 +1,2 @@
+# :fzf-tab:complete:(\\|*/|)nix-hash:argument-rest
+nix-hash $realpath
diff --git a/sources/nix-instantiate.zsh b/sources/nix-instantiate.zsh
new file mode 100644
index 0000000..94d5cc7
--- /dev/null
+++ b/sources/nix-instantiate.zsh
@@ -0,0 +1,6 @@
+# :fzf-tab:complete:(\\|*/|)nix-instantiate:*
+case $group in
+(shortcuts|'Local file'))
+  nix-instantiate --eval $word | bat --color=always -plnix
+  ;;
+esac
diff --git a/sources/nix-store.zsh b/sources/nix-store.zsh
index 0ae1fce..32a86d9 100644
--- a/sources/nix-store.zsh
+++ b/sources/nix-store.zsh
@@ -1,2 +1,6 @@
-# :fzf-tab:complete:(\\|*/|)nix-build:option-A-1
-nix-build --no-out-link '<nixpkgs>' -A $word
+# :fzf-tab:complete:(\\|*/|)nix-store:*
+case $group in
+'Store Paths')
+  nix-store -q --tree $realpath
+  ;;
+esac