managers: system, session, window, volume, preference (and some use a display)

Links: using systemd as a session manager ::

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I miss the SysV days when system, session, window (eg. "compositing"), volume, preference, and display managers were all cleanly defined. In fact, we never even needed the preference manager, gconf, because configurations were done with simple text files for each app. I'm just a regular user, and it takes me a lot of work these days to keep these managers separate or find their configuration files. They also seem to intertwine on occasion, requiring detangling time, as well.

Display Manager Disclaimer

Logins, startx, and shutdown are the only terminal commands needed in a normal session. Display Managers are only needed to make these more aesthetic. Accordingly, I haven't used a display manager in ten years. Why have an aesthetic login if it costs memory and potential fails? Second, not using it removes one variable from the kludge of 6 managers just listed above. Display Managers inadvertently obscure any start-up fails by keeping text log access out of sight. That's a problem during an install. In fact, during installs, I obtain a solid Runlevel 2 before downloading any X elements.

Session manager sussed-out

I attempted to tweak Evince's default zoom level the other day without gvfs (gnome's volume manager) installed. Sadly, Evince does not use old-skool config files; users have to set "schema keys", which are probably xml files. At any rate, one starts at the top, the correct schema, and then one modifies its key: find the schema, then its possible keys. To shorten the codeblock below, here were the two Evince-related schemas using the list-schema flag :

$ gsettings list-schemas
org.gnome.Evince.Default
org.gnome.Evince

And then the keys for those schemas.

$ gsettings list-keys org.gnome.Evince
document-directory
auto-reload
override-restrictions
page-cache-size
allow-links-change-zoom
pictures-directory
show-caret-navigation-message

$ gsettings list-keys org.gnome.Evince.Default
window-ratio
continuous
fullscreen
show-toolbar
show-sidebar
dual-page-odd-left
inverted-colors
zoom
sidebar-page
sidebar-size
dual-page
sizing-mode

It appears the "zoom" key is the one to set, which is in schema Evince.Default.

$ gsettings set org.gnome.Evince.Default zoom 1.0
$ gsettings get org.gnome.Evince.Default zoom
1.0

We can see the zoom was set correctly (to 100%). Now let's run Evince:

$ evince
GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files

Evince starts, but spawns the error above and only the default zoom factor, instead of the 100% zoom I entered.

Was gnome-session not running, sharing with systemd, or what? A simple setting can often means days of frustration in Linux. If I recall correctly, it's further the case, that gnome-session can only be started after dealing with PAM, like via gdm-password. It's unlikely any gnome sessions are running.

# ps -A |grep -i g
614 ? 00:00:00 gconfd-2
3602 pts/2 00:00:00 grep
31658 ? 00:00:00 gnome-pty-helpe

Now it's clear: no gnome-session is running. The gsetting commands were accepted. That is because, for the settings to be entered, only gconfd, gnome's preference manager, had to be running. However, there was no way to implement those preferences, because the session manager, gnome-session, was not running: an error message was generated. Meanwhile, Arch recommends against any gconf schemas, and notes they will soon be replaced with "dconf". Currently then, Evince is probably caught in the middle of these. We really have no way to configure Evince without getting a session manager going, which in turn probably requires the dreaded gvfs by the way.

Okular

In spite of the immense KDE libraries necessary for Okular, I have to look. I mean if I can just set preferences at this point, I'd be happy.