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

[Liam O'Toole]

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