CentOS - Apr 2015 - Problems with getty and X on runlevel switch [Was: Re: The future of centos]

On 2015-04-08, David Both
<dboth at millennium-technology.com>
wrote:
> The easy way to restart gdm is when you are on the login screen itself
> or the desktop simply press Ctrl-Alt-Backspace. This works for Upstart
> in CentOS 6.x but will not work for CentOS 7.x which uses Systemd. The
> service command does not work for gdm. However, logging out of the
> desktop will restart gdm. It works for the graphical login exactly
> like the gettys in a TTY environment.
Thanks for the suggestion.

Logging out and keying ctrl-alt-backspace both restart X, certainly, but
I'm not so sure about gdm. I'm not at a CentOS 6 machine right now so I
can't confirm one way or the other.
>
> On 04/08/2015 06:36 AM, Liam O'Toole wrote:
>> On 2015-04-04, Bill Maltby (C4B)
>> <centos4bill at gmail.com>  wrote:
>>> On Sat, 2015-04-04 at 11:12 +0100, Nux! wrote:
>>>> 100% with Digimer here.  <snip> All this energy should be
put into
>>>> contributing towards to the project, testing, helping out
>>>> community.
>>> Well, I used to agree. But when a bug report filed in December goes
>>> untouched entering April, which I don't recall happening prior
to RH
>>> subsuming the project, it takes away impetus to ever file one again
>>> from lowly end users like me I think.
>>>
>>> http://bugs.centos.org/view.php?id=7972
>> Thanks for drawing my attention to that bug. I encountered it the
>> other day after switching from runlevel 5 to 3 (and back again) on a
>> CentOS 6.6 machine.
>>
>> The purpose of the runlevel switch was to restart gdm. Is there a
>> better way?
>>
>
>
-- 

Liam

Am 08.04.2015 um 16:22 schrieb Liam O'Toole <liam.p.otoole at
gmail.com>:
> On 2015-04-08, David Both
> <dboth at millennium-technology.com>
> wrote:
>> The easy way to restart gdm is when you are on the login screen itself
>> or the desktop simply press Ctrl-Alt-Backspace. This works for Upstart
>> in CentOS 6.x but will not work for CentOS 7.x which uses Systemd. The
>> service command does not work for gdm. However, logging out of the
>> desktop will restart gdm. It works for the graphical login exactly
>> like the gettys in a TTY environment.
> 
> Thanks for the suggestion.
> 
> Logging out and keying ctrl-alt-backspace both restart X, certainly, but
> I'm not so sure about gdm. I'm not at a CentOS 6 machine right now
so I
> can't confirm one way or the other.

gdm is a "sub-process" of X ...

--
LF

On 2015-04-08, Leon Fauster
<leonfauster at googlemail.com> wrote:
> Am 08.04.2015 um 16:22 schrieb Liam O'Toole
> <liam.p.otoole at gmail.com>:
>> On 2015-04-08, David Both
>> <dboth at millennium-technology.com>
>> wrote:
>>> The easy way to restart gdm is when you are on the login screen
>>> itself or the desktop simply press Ctrl-Alt-Backspace. This works
>>> for Upstart in CentOS 6.x but will not work for CentOS 7.x which
>>> uses Systemd. The service command does not work for gdm. However,
>>> logging out of the desktop will restart gdm. It works for the
>>> graphical login exactly like the gettys in a TTY environment.
>> 
>> Thanks for the suggestion.
>> 
>> Logging out and keying ctrl-alt-backspace both restart X, certainly,
>> but I'm not so sure about gdm. I'm not at a CentOS 6 machine
right
>> now so I can't confirm one way or the other.
>
>
> gdm is a "sub-process" of X ...
>
> -- LF
Not according to the output of pstree. See the following snippet:

     ??gdm-binary???gdm-simple-slav???Xorg
     ?            ?                 ??gdm-session-wor???gnome-session???bluetoo+
     ?            ?                 ?                 ?               ??compiz?+
     ?            ?                 ?                 ?               ?        +
     ?            ?                 ?                 ?               ??gdu-not+
     ?            ?                 ?                 ?               ??gnome-p+
     ?            ?                 ?                 ?               ??gpk-upd+
     ?            ?                 ?                 ?               ??nautilu+
     ?            ?                 ?                 ?               ??polkit-+
     ?            ?                 ?                 ?               ??python
     ?            ?                 ?                 ?               ??restore+
     ?            ?                 ?                 ?               ??{gnome-+
     ?            ?                 ?                 ??{gdm-session-wo}
     ?            ?                 ??{gdm-simple-sla}
     ?            ??{gdm-binary}

Xorg is in fact a sub-sub-process of gdm-binary.

While logged into a GNOME session, I ran the pgrep command as follows:

$ pgrep -fl gdm
1583 /usr/sbin/gdm-binary -nodaemon
1619 /usr/libexec/gdm-simple-slave --display-id
/org/gnome/DisplayManager/Display1
1622 /usr/bin/Xorg :0 -br -verbose -audit 4 -auth
/var/run/gdm/auth-for-gdm-EcVz3c/database -nolisten tcp vt1
1801 pam: gdm-password

I restarted X using ctrl-alt-backspace, logged back in and ran the command
again:

$ pgrep -fl gdm
1583 /usr/sbin/gdm-binary -nodaemon
1619 /usr/libexec/gdm-simple-slave --display-id
/org/gnome/DisplayManager/Display1
1622 /usr/bin/Xorg :0 -br -verbose -audit 4 -auth
/var/run/gdm/auth-for-gdm-EcVz3c/database -nolisten tcp vt1
1801 pam: gdm-password

X has indeed restarted, but the gdm-related processes have not.

-- 

Liam