fix: dkpurge->dkprune, better perm test

bin/dkprune

@@ -28,8 +28,8 @@ function add_opt() {
     echo "$RESULT"
 }
 
-if ! docker container ls > /dev/null 2>&1 && [ "$EUID" != 0 ]; then
-    exec sudo -- "$0" "$@"
+if ! [ -w "/var/run/docker.sock" ] && [ "$EUID" != 0 ]; then
+    sudo -- "$0" "$@"
 fi
 
 c=1
@@ -73,11 +73,11 @@ while getopts hcCviIna o; do
     esac
 done
 
-if [ "$((CLEAN & C))" == "$C" ]; then # C
+if [ "$((CLEAN & C))" == "$C" ]; then
     docker container ls -aq | xargs docker stop
 fi
 
-if [ "$((CLEAN & c))" == "$c" ]; then # C
+if [ "$((CLEAN & c))" == "$c" ]; then
     docker container prune -f
 fi