I thought that the rescue target, which I can enter from multi-user with the commands systemctl rescue or systemctl isolate rescue, is single-user mode.

However I just found that on my Centos 8 server, existing interactive sessions continue. Also, systemctl rescue is supposed to send a message to all logged-in users but doesn't. I also expected it to shut down networking - it is obviously up.

The sshd service is shut down.

On a Debian 10 server, the behavior is different. The main network interface is shut down, but the bash process that I launched by logging on via ssh is still running.

I expected all interactive sessions and the network interfaces to be stopped. Is there a problem with the servers' configuration or is my expectation wrong?

Never considered it - but that command is documented as blocking. Why would you use it in preference to a reboot specifying a boot target ?.

I don't care that it's blocking. Rebooting and entering the rescue target requires altering the Grub menuentry, which is more work, less convenience and slightly risky.

I guess I just don't like undocumented behaviour, or behaviour that contradicts documentation. According to the documentation, systemctl rescue is the same as systemctl isolate rescue.target, and isolate means that services that are not in the rescue target should be stopped. This doesn't happen.

So yes I am complaining, but perhaps there is really something that I don't understand correctly.