Difference between revisions of "LXDM"

Revision as of 07:37, 25 November 2013

zh-CN:LXDM

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.

Installation

The lxdm package is available in the official repositories or lxdm-git^AUR 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 he has logged in.
4. PostLogout is run as the logged-in user right after he has logged out.
5. PreReboot is run as root before rebooting with LXDM.
6. PreShutdown is run as root before poweroff with LXDM.

Default session

It can be specified which session will be loaded when the users select the 'Default' session from the session list. Note that the user setting takes preference over global setting.

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

Example using GNOME:

session=/usr/bin/gnome-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. To avoid this, delete the password:

$ passwd -d USERNAME

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

Tips and tricks

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.

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

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

If you use the Xfce desktop, the Switch User functionality of its Action Button panel item specifically looks for the gdmflexiserver executable in order to enable itself. If you provide it with an executable shell script /usr/bin/gdmflexiserver consisting of

 #!/bin/sh
 /usr/bin/lxdm -c USER_SWITCH

then user switching in Xfce should work fine also with LXDM.

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

Themes

The LXDM themes are localized in /usr/share/lxdm/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.

There are 2 themes provided with lxdm-git^AUR. ArchStripes and ArchDark. You can configure them on /etc/lxdm/lxdm.conf in theme=theme_name

Troubleshooting

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

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

Another option than killall is to use loginctl:

#!/bin/sh

# Terminate current user session
/usr/bin/loginctl terminate-session $XDG_SESSION_ID

# Restart lxdm
/usr/bin/systemctl restart lxdm.service

.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"

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