Suppose you walk up to a system and want to know the date it was last updated?
How do you find that info? Or, is there an app (like lsb-release for example) that will give it to you?
Hopefully there is a method that would apply both to 15.4 and TW?
TW is listed in /etc/os-release but leap systems don’t show a date there
TIA
I think it is a bit difficult to determine “the last update applied to the system” Because I would not really know how to define that. It is possible to find out what the installation date/time was of an individual package (first installation or later update of it). But there is no package that defines “the system”. And even if there is one, it will not be updated when some other package is updated.
Maybe you should think it over and try to define what you really want and for what reason.
E.g. taking a note about the last time zypper patch or zypper dup or YaST > Online Update was done might be doable (there are zypp loggs), but that does not inform about the fact that the update of one or more packages was skipped for some reason (e.g. install all updates available, but not the kernel because the system is in use and can not be re-booted now, thus postpone). So it will not tell you if every package with a newer version then installed, that was available at the update moment, was really updated.
And as said above, updating to a newer version of software not stored in repositories (downloaded RPMs, build from tarballs), is not covered here, but I assume that is clear.