handling busybox linux timezones

the busybox base linux QTS has no timedatectl command. In case the
timedatectl command isn't available, the default timezone is taken
from /etc/TZ and translated via /etc/tzlist.

If those files also don't exist, it simply default to GMT
(Europe/London)

install-paperless-ngx.sh

@@ -71,7 +71,16 @@ if ! docker stats --no-stream &> /dev/null ; then
 	sleep 3
 fi
 
-default_time_zone=$(timedatectl show -p Timezone --value)
+# Added handling for timezone for busybox based linux, not having timedatectl available (i.e. QNAP QTS)
+# if neither timedatectl or /etc/TZ is suceeding, defaulting to GMT.
+if  command -v timedatectl &> /dev/null ; then
+        default_time_zone=$(timedatectl show -p Timezone --value)
+elif [ -f /etc/TZ ] && [ -f /etc/tzlist ] ; then
+        TZ=`cat /etc/TZ`
+        default_time_zone=$(grep -B 1 -m 1 $TZ /etc/tzlist | head -1 | cut -f 2 -d =)
+else
+        default_time_zone="Europe/London"
+fi
 
 set -e