To [install](/doc/templates/#installing) a specific Debian TemplateVM that is not currently installed in your system, use the following command in dom0:
For routine daily TemplateVM updates within a given Debian release, see [Updating software in TemplateVMs](/doc/software-update-domu/#updating-software-in-templatevms).
- [Install a fresh template to replace the existing one.](#installing) This option may be simpler for less experienced users. After you install the new template, redo all desired template modifications and [switch everything that was set to the old template to the new template](/doc/templates/#switching). You may want to write down the modifications you make to your templates so that you remember what to redo on each fresh install. In the old Debian template, see `/var/log/dpkg.log` and `/var/log/apt/history.log` for logs of package manager actions.
- [Perform an in-place upgrade of an existing Debian template.](/doc/template/debian/upgrade/) This option will preserve any modifications you've made to the template, but it may be more complicated for less experienced users.
The Debian way (generally) is to start daemons if they are installed.
This means that if you install (say) ssh-server in a template, *all* the qubes that use that template will run a ssh server when they start. (They will, naturally, all have the same server key.) This may not be what you want.
So be very careful when installing software in Templates - if the daemon spawns outbound connections then there is a serious security risk.
In general, a reasonable approach would be, (using ssh as example):
