Bug#990019: #990019, initscripts: single user mode broken with newer versions of systemd

[Mark Hindley]

On Fri, Jun 18, 2021 at 09:55:42AM -0300, Jesse Smith wrote:
> The issue here is that the init script (/etc/init.d/single) is trying to
> call SysV init with the "-t1" flag, which is not valid. There is no -t
> flag or -t1 flag for init.
> 
> I suspect what the script was intended to do is call "/sbin/telinit -t 1
> s". This would switch to single user mode after a delay of just one second.

I can't see any indication of the original intention for using the -t1 flag. It
has been that way since commit 9184ce235175aeae2725650d34af2c1486b6a73c made in
2005!

The systemd version of telinit doesn't appear to support the -t option[1],
although I think systemd masks single.service to avoid using
/etc/init.d/single. But, I suppose a user could circumvent that.

The most compatible way to deal with this is probably just to remove the -t1
option completely.

Mark

[1]  https://manpages.debian.org/stretch/systemd-sysv/telinit.8.en.html