Re: Single-user actions on reboot

On 9/29/23 08:49, Guido Falsi wrote:
> On 29/09/23 15:21, Jason Bacon wrote:
>>
>> I'm wondering if there's a canonical way to schedule a command to run 
>> automatically during the next boot cycle, but before going multiuser.
>>
>> This would be useful, for example, to run certain tunefs commands on 
>> /, which can only be done in single-user mode, on remotely managed 
>> systems.
>>
>> Running things after going multiuser is easy, of course, but not 
>> sufficient for tunefs commands that cannot be performed on a 
>> filesystem mounted rw.
>>
>> Thanks...
>>
> 
> AFAIK there is no ready made tool in base (or ports) for that.
> 
> But ezjail uses this trick with rc scripts (removing itself):
> 
> https://erdgeist.org/gitweb/ezjail/tree/examples/example/etc/rc.d/ezjail.flavour.example
> 
> This is effective but requires the disk mounted r/w which maybe is not 
> enough for you.
> 
> Problem is, without any writable media mounted, how can any script 
> register it has already ran?
> 
> One idea that comes to mind is adding some hook to the main rc script, 
> before mounting disk r/w, and a second script that removes existing 
> hooks once disks are r/w.
> 

Thanks for the brainstorming, gents.  This helped narrow my direction, 
and I implemented what I need by creating a /etc/rc.d/local_early based 
on the standard /etc/rc.d/local:

https://github.com/outpaddling/auto-admin/blob/master/Data/local_early
https://github.com/outpaddling/auto-admin/blob/master/Data/rc.local_early

The only real difference is when it runs.

As an example of how to use it, to toggle the soft-updates journal using 
tunefs, I generate a script like the following and drop it in 
/etc/rc.local_early.d.  It runs on the next reboot and removes itself.

for fs in  /dev/ada0s1a /dev/da0p1; do
     tunefs -j disable $fs
     mount -u -o rw /
     rm -f /etc/rc.local_early.d/auto-su+j-toggle.sh
done
reboot

This is now integrated into auto-su+j-toggle (WIP version), part of 
sysutils/auto-admin.

-- 
Life is a game.  Play hard.  Play fair.  Have fun.