LightDM - Apr 2018 - Bootloop after tried to run a custom script

Hi,

recently I had a seriously problem with LightDM. I wrote a custom Bash
script that do something, and I wanted to run this script before the
greeter (I use GTK+ greeter) is launched. So I wrote this on my
lightdm.conf:

	greeter-setup-script=custom script

I didn't check if lightdm could reach the script, because I forgot to
move it on /usr/local/bin. So I restarted the computer, and LightDM
started to loop infinitely.

I resolved using Debian recovery mode. I inserted the path after the
script name:

	greeter-setup-script=/usr/local/bin/background-selector

and it worked perfectly.

Why a simple script blocked the booting process? Doesn't LightDM check
if the script or command can be executed? And if it can't, why it
doesn't skip it?

I'm using Debian Stable, lightdm 1.18.3.

-- 
Emanuele Petriglia

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Hi Emmanuele,

It's a difficult choice, because LightDM can't determine how important
the
script is. The current logic is, if the script fails to run, then the
greeter is not considered to be started and so nothing can be displayed. To
display the greeter might cause the wrong thing to happen, so we err on the
side of caution.

There's two ways out of this:
- We could add an option, to configure the behaviour of lightdm in regard
to scripts. I'm wary of this, because it would be very obscure.
- Is the functionality in your script suitable for inclusion into the
greeter code? The script support is provided because existing display
managers had them, but ideally they shouldn't be required.

On Mon, 2 Apr 2018 at 06:20 Emanuele Petriglia <inbox at
emanuelepetriglia.me>
wrote:
> Hi,
>
> recently I had a seriously problem with LightDM. I wrote a custom Bash
> script that do something, and I wanted to run this script before the
> greeter (I use GTK+ greeter) is launched. So I wrote this on my
> lightdm.conf:
>
>         greeter-setup-script=custom script
>
> I didn't check if lightdm could reach the script, because I forgot to
> move it on /usr/local/bin. So I restarted the computer, and LightDM
> started to loop infinitely.
>
> I resolved using Debian recovery mode. I inserted the path after the
> script name:
>
>         greeter-setup-script=/usr/local/bin/background-selector
>
> and it worked perfectly.
>
> Why a simple script blocked the booting process? Doesn't LightDM check
> if the script or command can be executed? And if it can't, why it
> doesn't skip it?
>
> I'm using Debian Stable, lightdm 1.18.3.
>
> --
> Emanuele Petriglia
>
> _______________________________________________
> LightDM mailing list
> LightDM at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/lightdm
>
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