X

Configuration

• xset is a user preference utility for X. It can be used to set different settings in X.
  To get the current configuration settings:

xset q

Hints and Tips

See Linux Commands for a list of X-related commands, and programs to manage key bindings in X. See Linux Software for list of X-related software.

Screenshot

• In Gnome,
  • Press PrtScn to take a screenshot of the complete desktop.
  • Press Alt + PrtScn to take a snapshot of window under mouse pointer.
• See all Linux Software#Shutter
• There exists also plenty of command-line & GUI solutions ([1]).

Enabling xhost on Ubuntu

For security, xhost is disabled by default on Ubuntu. To enable it back ([2]):

• Edit /etc/X11/xinit/xserverrc:
  Remove the -nolisten tcp
• Edit /etc/gdm/gdm.conf:
  Comment out the DisallowTCP=true so that it doesn't add the -nolisten back.
• Really restart X — kill gdm and restart it:

sudo /etc/init.d/gdm stop 
sudo /etc/init.d/gdm start

Set or Get information on Screen Size and Resolution

To get information on the screen size and resolution, use utility xdpyinfo:

xdpyinfo | grep dimensions               # Return dimension of the desktop (size in pixels and millimeters)
xdpyinfo | grep resolution               # Return current screen resolution in DPI (dots per inch)

Some basic information on screen size, DPI, etc:

point (pt)	The point or pt is a typographic unit defined as 1/72 of an inch
DPI	Dots per inch, i.e. the number of pixels by screen inch. Most monitors nowadays have a resolution of 96 DPI.

As explained here, the DPI of the X-server is determined as follows:

• -dpi command line option has highest priority.
• If not set, look up DisplaySize setting in the X config file.
• If not set, use the monitor size values from DDC to derive the DPI.
• If unknown, 75 DPI is used by default.

Windows Manager

References

• http://ubuntulinuxtipstricks.blogspot.com/2008/12/compiz-emerald-metacity-what.html

The function of the window manager is to draw the windows in a certain place, with a certain size, and let them be movable and resizable.

Most common Window Managers on Ubuntu:

• Metacity — The default GNOME Window Manager
• Kwin — KDE Window Manager
• Compiz

Windows Decorator

The window decorator draws the window borders. It is not necessary to move the window, since alt+click & drag will still work even when the window decorator has crashed.

• Metacity has its own window decorator built-in
• KWin also has its own window decorator built-in
• Compiz supports 3 different window decorators:
  • gtk-window-decorator
  • kde-window-decorator
  • emerald — The window decorator inherited from Beryl, the ancestor of Compiz.

Themes

Gnome:

• GTK theme — controls how buttons look, the colors of text, the window background, the scrollbars, and the menubar styles.
• Metacity theme — just controls the window border's style.

KDE:

• Qt theme — does the buttons, scrollbars, etc.,
• Kwin has its own themes for window borders.

When Compiz is used, the theme used depends on the selected window decorator. gtk-window-decorator uses Metacity themes, kde-window-decorator used kwin themes, Emerald has its own themes.

wmctrl / xdotool

Use wmctrl or xdotool to send X events or control windows from the command line:

wmctrl -l -x                                                      # Get list of windows
wmctrl -r :ACTIVE: -b remove,maximized_vert,maximized_horz        # Un-maximize current active window

# Move windows to different viewports
xdotool search --onlyvisible --classname Opera  set_desktop_viewport 0 0 windowmove %@ 1600 0
xdotool search --onlyvisible --classname Gvim  set_desktop_viewport 0 0 windowmove %@ 0 0
xdotool search --onlyvisible --class VirtualBox  set_desktop_viewport 3200 0 windowmove %@ 0 0

xprop

Use xprop to display X properties on a window, fonts, etc. Without any parameters, xprop will display properties on window clicked by the user.

xprop                             # Show properties on window clicked by the user

xev

Use xev (package x11-utils) to detect keyboard or mouse presses, as well as any X events (show keycode - i.e. scancode, keypress, button press...).

Mouse

To adjust mouse properties, use xset m. Default settings (restored with xset m):

Pointer Control: acceleration:  2/1    threshold:  4

Set custom settings:

xset m 1/1 2         # xset m [acc_mult[/acc_div] [thr]]

In Gnome, mouse settings can also be configured in System → Hardware → Mouse.

Keyboard

Qwerty / Azerty Issues

Some tips and tricks to (touch-)type on a QWERTY keyboard when the keymap is set to AZERTY.

The main issue is that AZERTY keyboard has an additional key next to the left SHIFT key. This key gives access to <, to > (Shift) and to \ (AltGr). To obtain these keys on a QWERTY keyboard, the basic trick is to temporarily switch the keyboard layout. Alternatively, one can use under X:

• <:
• >:
• \: Use AltGr-- (on QWERTY, i.e. AltGr-) on AZERTY)

Layout

To change keyboard layout (xfree86):

#Set to BE layout
xprop -root -f _XKB_RULES_NAMES 8s -set _XKB_RULES_NAMES xfree86
setxkbmap -model pc105 -layout be
#Set to US layout
xprop -root -f _XKB_RULES_NAMES 8s -set _XKB_RULES_NAMES xfree86
setxkbmap -model pc104 -layout us

Multiple keyboards - Change keyboard layout on each device separately ([3])

setxkbmap -device 3 af       #Set device 3 to Farsi (to find device id, try 1 and then up)
setxkbmap -device 3 us       #Set it back to US

Configuring Layout Options

X supports a wide range of layout options. See xkeyboard-config manpage for a list:

man 7 xkeyboard-config

The most interesting options:

• caps:escape — Make Caps Lock another Escape key
• caps:swapescape — Swap Caps Lock and Escape key

Use setxkbmap to set temporarily layout options:

/usr/bin/setxkbmap -option "caps:escape"

There are various options to make these settings permanent for the user:

• In Ubuntu, use Keyboard layout applet in system configuration, and click Options — no longer available in u14.04 trusty
• Use dconf-tools and go org >> gnome >> desktop >> input-sources, then edit xkb-options to make the options permanent

sudo apt-get install dconf-tools

• Alternatively, use gnome-tweak-tool [4]

To make the settings permanent system-wide:

• Create file /usr/share/X11/xorg.conf.d/10-keyboard.conf (on Debian / Ubuntu; this is /etc/X11/xorg.conf.d/10-keyboard.conf on other systems). Example of content [5]:

Section "InputClass"
        Identifier "system-keyboard"
        MatchIsKeyboard "on"
        Option "XkbLayout" "us"
        Option "XkbModel" "pc104"
        Option "XkbOptions" "shift:both_capslock,caps:none"
EndSection

Brightness

Various way to control laptop screen brightness

• In Ubuntu, open the Brightness & Lock settings applet.
• Use the keyboard Fn keys Fn+Brightness up/down
• Via command-line by editing /sys/class/backlight/intel_backlight (from bug 847001:

cat /sys/class/backlight/intel_backlight/max_brightness
# 976
cat /sys/class/backlight/intel_backlight/brightness
# 123
echo 600 | sudo tee /sys/class/backlight/intel_backlight/brightness
# 600
echo 200 | sudo tee /sys/class/backlight/intel_backlight/brightness
# 200

• Using xbacklight

xbacklight -set 100

• Using setpci. See for example on Samsung NC10 page:

sudo setpci -s 00:02.1 f4.b=77     # where 77 (00-ff) is the brightness value

Synergy

Install Windows Client

• Execute setup program.
• Set the client to start automatically at PC startup
• Set the service Synergy Client to start manually.
• Check that the keymap for all users are identical.
• To launch the client:

net start "Synergy Client"

Install Linux Client

• Manual launch:

sudo synergyc --daemon --restart -n clientname servername

Install Linux Server

• Configuration file /etc/synergy.conf (see [http://synergy2.sourceforge.net/configuration.html reference manual)
. Example

section: screens
	gryphon:
	BEQLEUNXP1NB103:
	minimoy:
end
section: links
	gryphon:
		left = BEQLEUNXP1NB103
		right = minimoy
	BEQLEUNXP1NB103:
		right = gryphon
	minimoy:
		left = gryphon
end
section: options
	screenSaverSync = true
	keystroke(shift+alt+right) = switchInDirection(right)
	keystroke(shift+alt+left) = switchInDirection(left)
end

• Firewall — open up port 24800/TCP
• Server on gdm — Requires editing 3 gdm startup scripts. /etc/gdm/Init/Default:

#
# Start the synergy server
#
/usr/bin/killall synergys
sleep 1
/usr/bin/synergys --config /etc/synergy.conf --daemon

exit 0

• At the beginning of /etc/gdm/PostLogin/Default:

#
# Kill all running synergy server
#
/usr/bin/killall synergys
sleep 1

• At the beginning of /etc/gdm/PreSession/Default:

#
# Start synergy server
#
/usr/bin/killall synergys
sleep 1
/usr/bin/synergys --config /etc/synergy.conf --daemon

Starting manually with aliases

The aliases make it easy to restart synergy on the client / server in case of crashes (quite frequent),

Add to /etc/sudoers:

ALL	ALL=NOPASSWD: /usr/bin/synergyc
ALL	ALL=NOPASSWD: /usr/bin/synergys
ALL	ALL=NOPASSWD: /usr/bin/killall -9 synergyc
ALL	ALL=NOPASSWD: /usr/bin/killall -9 synergys

Define the following aliases:

alias synclient="sudo killall -9 synergyc; read -p 'Press ENTER...'; sudo synergyc --daemon --restart -n $HOSTNAME"
alias synserver='sudo killall -9 synergys 2>/dev/null; read -p "Press ENTER..."; sudo synergys --daemon --restart --config /etc/synergy.conf'

To start synergy:

synserver                          # On the server
synclient <servername>             # On the client

Building from sources

Instructions to build synergy 1.3.8 on Lucid.

Build instructions say that we have to use cmake and the given hm.sh script. However that does not work! The script always complains about a missing generator argument, even though we try to give it in all possible ways.

Instead, do the usual configure; make:

• Install the dependencies:

sudo apt-get install cmake make g++ xorg-dev libqt4-dev

• Unpack the archive, then

./configure
make
sudo cp bin/synergyc /usr/bin
sudo cp bin/synergys /usr/bin

Troubleshoot

• Sticky modifier keys (ctrl/alt/shift), desync capslock — This problem occurs at least one during my Linux - Linux session (Ubuntu Lucid client, Maverick client), belgium keyboard. Also Capslock event not seen on client. Some related bugs: [6], [7].
• Firefox Chinese bug — When copy/pasting text (incl. address bar) from Firefox to a remote Windows screen, chinese characters are printed instead. Workaround:

sudo apt-get install xsel           # Install xsel (Ubuntu) / xselection (opensuse)
xsel -p                             # (Ubuntu) Before pasting in the remote Windows screen
xselection PRIMARY                  # (opensuse)

• Security — Data are not encrypted between the server and the client(s). To enable this, use SSH port forwarding. Run on the remote client:

ssh -f -N -L 24800:<server-name>:24800 <user-server-name>@<server-name> && synergyc localhost

However, this creates some lag, and mouse movement are a bit jerky. Another solution is to not use wireless connection, and connect computers through a network switch so that local communication are not visible to other computers on the network.

• Login / Unlocking screen saver on Windows client — On Windows client, Synergy must be configured to autostart at boot in order to be able to unlock a session (eg. when client screensaver is protected by a password).
• Keymaps — Server and all client must be configured to all use exactly the same keymap. On Windows client, this is valid for logged user but also for at least Administrator account. Otherwise typing in the login window will give incorrect characters.
• Can't get tilde character (~) on a Belgian-french keyboard on windows client / Linux server with AltGr=
Workaround: Use CA= followed by space.
• Can't connect to server. Possibly because synergy client not started with root privileges
• VirtualBox — When the Synergy Server is also a VirtualBox host, with the guest in fullscreen mode, the mouse will not leave the guest screen. It seems that VirtualBox doesn't release the mouse. See bugs [8], [9], [10].
Workarounds:
• Press VB Host Key (typically ctrl), either before or after going to Synergy Client. — tried and works on Synergy 1.3.7 - VB 4.0.10
• Disable VB mouse integration