dracut-functions.sh: use builtin bash functions rather than tr

convert uppercase to lowercase using bash syntax

diff --git a/dracut-functions.sh b/dracut-functions.sh
index 6c7e693d83c661168d6ac3c88bf3b021b1d788b0..87b976967c0dc4999ad84db163be81be68cd4ef0 100755 (executable)
--- a/dracut-functions.sh
+++ b/dracut-functions.sh
@@ -332,12 +332,12 @@ expand_persistent_dev() {
             ;;
         UUID=*)
             _dev="${_dev#UUID=}"
-            _dev="$(tr "[:upper:]" "[:lower:]" <<< "$_dev" )"
+            _dev="${_dev,,}"
             _dev="/dev/disk/by-uuid/${_dev}"
             ;;
         PARTUUID=*)
             _dev="${_dev#PARTUUID=}"
-            _dev="$(tr "[:upper:]" "[:lower:]"  <<< "$_dev" )"
+            _dev="${_dev,,}"
             _dev="/dev/disk/by-partuuid/${_dev}"
             ;;
         PARTLABEL=*)