DSK: Updates and code cleanup

.config/dsk/run/nitrogen

@@ -1,3 +1,3 @@
 #! /usr/bin/env bash
-which nitrogen > /dev/null 2>&1 || exit 0
+command -v nitrogen > /dev/null 2>&1 || exit 0
 exec nitrogen --restore

.config/dsk/run/xrdbupdate

@@ -1,5 +1,5 @@
 #! /usr/bin/env bash
 [ -r ~/.Xresources ] && xrdb ~/.Xresources
-for file in $XDG_CONFIG_HOME/xrdb/*.xresources; do
+for file in "$XDG_CONFIG_HOME"/xrdb/*.xresources; do
 	[ -r "$file" ] && xrdb -merge "$file"
 done