[systemd-devel] Hints for upgrading systemd on a running system

[Reindl Harald]

Am 20.02.2018 um 22:04 schrieb Mantas Mikulėnas:
> On Tue, Feb 20, 2018, 21:06 Reindl Harald <h.reindl at thelounge.net 
> <mailto:h.reindl at thelounge.net>> wrote:
> 
> 
>     Am 20.02.2018 um 20:00 schrieb Paul Menzel:
>      > Dear systemd folks,
>      >
>      > We finally are going to upgrade from a very old systemd version
>     27 from
>      > 2011 to the current systemd v237. (Historical reasons.)
> 
>     hopefully you have a working backup
> 
>      > Anyway, I already was told about `systemctl daemon-reexec`, and
>     we got
>      > it working.
> 
>     the "reexec" is misleading because it's not possible to terminate PID1
>     and start it again on a running system with a new binary
> 
> 
> But you don't *have to* terminate pid1 to change the binary – you can 
> just exec the new one. Hence the "reexec".
> 
> It's possible. That's how initramfs works

a lot of other threads here made it clear that there is not much 
difference between "daemon-reload" and "daemon-reexec" at all in the 
past and i strongly doubt that it's technically possible to seamless 
switch from version 27 (the first Fedora GA AFAIK hat version 44) to 237 
and keep the system happily running as like nothing has changed without 
reboot