LXDM

From ArchWiki
Revision as of 20:19, 18 May 2013 by Valr (Talk | contribs) (Session list)

Jump to: navigation, search
Summary help replacing me

LXDM is the lightweight display manager aimed to replace gdm in LXDE distros. The UI is implemented with GTK+. It is still in early stages of development.

Related
Display_Manager

Installation

The lxdm package is available in the official repositories or lxdm-gitAUR is available in the AUR.

Usage

Currently, lxdm provides an lxdm.service file. Enable it like any other systemd service:

# systemctl enable lxdm

Configuration

The configuration files for LXDM are all located in /etc/lxdm/. The main configuration file is lxdm.conf, and is well documented in its comments. Another file, Xsession, is the systemwide x session configuration file and should generally not be edited. The other files in this folder are all shell scripts, which are run when certain events happen in LXDM.

These are:

  1. LoginReady is executed with root privileges when LXDM is ready to show the login window.
  2. PreLogin is run as root before logging a user in.
  3. PostLogin is run as the logged-in user right after they have logged in.
  4. PostLogout is run as the logged-in user right after they have logged out.
  5. PreReboot is run as root before rebooting with LXDM.
  6. PreShutdown is run as root before poweroff with LXDM.
Warning: The language select control in lxdm.conf is sometimes required and sometimes not. Set lang= to inverse value of itself when LXDM potentially enters a boot loop and fails to load target sessions.

Unlocking keyrings upon login

When using a key manager such as gnome-keyring to manage passwords for ssh keys, /etc/pam.d/lxdm should be adjusted to allow users to unlock keyrings upon login if desired. Add the following to the package provided /etc/pam.d/lxdm:

auth            optional        pam_gnome_keyring.so
session         optional        pam_gnome_keyring.so auto_start

Adding face icons

A 96x96 px image (jpg or png) can optionally be displayed on a per-user basis replacing the stock icon. Simply copy or symlink the target image to $HOME/.face. The gnome-control-center package supplies some default icons suitable for the lxdm screen. Look under /usr/share/pixmaps/faces after installing that package.

Note: Users need not keep gnome-control-center installed to use this images. Simply install it, copy them elsewhere, and remove it.

Default session

Globally

Edit /etc/lxdm/lxdm.conf and change the session line to whatever session or DE is desired:

session=/usr/bin/startlxde

Example using xfce:

session=/usr/bin/startxfce4

Example using openbox:

session=/usr/bin/openbox-session

This is useful for themes that have no visible session selection box, and if experiencing trouble using autologin.

Per user

To define an individual user's preferred session, simply edit his/her respective ~/.dmrc to define the selection.

Example: user1 wants xfce4, user2 wants cinnamon, and user3 wants gnome:

For user1:

[Desktop]
Session=xfce

For user2:

[Desktop]
Session=cinnamon

For user3:

[Desktop]
Session=gnome

Autologin

To log in to one account automatically, without providing a password, find the line in /etc/lxdm/lxdm.conf that looks like this:

#autologin=username

Uncomment it, substituting the target user instead of "username".

This will cause LXDM to automatically login to the specified account when it first starts up. However, if one were to log out of that account, one would have to enter its password to log back into it; if the password was empty, that user will be unable to log into the account. To remedy this and be able to log into the account without entering a password, first delete the password:

$ passwd -d USERNAME

Then, edit the PAM file for LXDM, which is /etc/pam.d/lxdm. The files in this directory describe how users are authenticated by the various installed programs that need to do some sort of authentication. Change the line that says:

auth    required    pam_unix.so

to this:

auth    required    pam_unix.so nullok

This will tell the pam_unix authentication module that blank passwords are to be accepted. After making this change, LXDM will log into accounts with blank passwords.

Expected logout behavior

What might be slightly surprising with LXDM is that, by default, it does not clear the last user's desktop background or kill the user's processes when that user logs out. Users desiring this behavior, can edit /etc/lxdm/PostLogout like this:

#!/bin/sh

# Kills all your processes when you log out.
killall --user $USER -TERM

# Sets the desktop background to solid black. Useful if you have multiple monitors.
xsetroot -solid black

Another option than killall is to use loginctl

# Terminate user sessions and all related jobs
loginctl terminate-user $USER
Note: This will kill daemons such as tmux, urxvtd, etc.

Users can replace killall command with the following to exclude ssh and screen processes from termination:

ps --user $USER | egrep -v "ssh|screen" | cut -b11-15 | xargs -t kill

Or to (hopefully) only kill X-Processes and childs:

ps --user $USER | cut -f1,2 -d' ' | egrep "\?$" | cut -d' ' -f1 | xargs -t kill

Shutdown and reboot commands

Shutdown and reboot commands can be configured in /etc/lxdm/lxdm.conf by adding the [cmd] section:

[cmd]
# reboot command
reboot=/usr/bin/systemctl reboot

# shutdown command
shutdown=/usr/bin/systemctl poweroff

Session list

To add/remove entries to LXDM's session dropdown menu; create/remove the .desktop files in /usr/share/xsessions as desired. A typical .desktop file will look something like:

[Desktop Entry]
Encoding=UTF-8
Name=Openbox
Comment=Log in using the Openbox window manager (without a session manager)
Exec=/usr/bin/openbox-session
TryExec=/usr/bin/openbox-session
Icon=openbox.png
Type=XSession

.xinitrc

By default, lxdm doesn't read ~/.xinitrc but ~/.xprofile. That setup is defined in the /etc/lxdm/Xsession script. The default behaviour can be adapted by modifying the Xsession file like this:

#!/bin/bash

LXSESSION="$1"

if [ -f ~/.xinitrc ]; then
  . ~/.xinitrc lxdm
fi

exec /bin/bash -l -c "$LXSESSION"

Simultaneous users and switching users

LXDM allows multiple users to be logged into different ttys at the same time. The following command is used to allow another user to login without logging out the current user:

$ lxdm -c USER_SWITCH
Note: When the new user logs in, his/her session is now on the NEXT tty. For example, user1 logs in and issues the USER_SWITCH command. Now user2 logs in. User2 will be on tty8 while user1 will be on tty7.

Xscreensaver can also perform this task. For more, see the Xscreensaver#LXDM article.

PulseAudio

After a user logs out, subsequent users have no access to PulseAudio. The reason is that PulseAudio stores server credentials as properties on the X11 root window, and since LXDM does not restart the X server, these properties are not cleaned up and prevent the sound server from starting up for the next users. To remove these properties on logout, add the following line to /etc/lxdm/PostLogout:

test -x /usr/bin/pax11publish && /usr/bin/pax11publish -r

Themes

There is only one theme provided with lxdm, namely Industrial. To display the background file wave.svg which is part of this theme, make sure you have librsvg installed.