Support 'ubuntu' ID, add symlink /etc/pkglist for Slackware.

cronjob-update-packages-list

@@ -11,11 +11,12 @@
 
 # Create package list depending on system type.
 case "$ID" in
-  'debian')
+  'debian'|'ubuntu')
     /usr/bin/dpkg-query --show --showformat='${Package}\n' >/etc/pkglist
     ;;
   'slackware')
     /usr/sbin/slackpkg -batch=on -default_answer=y generate-template "$(hostname --short)" >/dev/null
+    [[ ! -e "/etc/slackpkg/templates/$(hostname --short).template" ]] && ln -sf "/etc/slackpkg/templates/$(hostname --short).template" /etc/pkglist
     ;;
   'void')
     /usr/sbin/xbps-query -l | awk '{ print $2 }' | rev | cut -d- -f2- | rev >/etc/pkglist