Forked from and inspired by haimgel/display-switch

Automate (KVM) monitor switching with a key combination

This utility allows to switch (mulitple) monitor inputs by pressing a key combination. Some monitors (eg. Dell U3419W) have built-in USB hub with multiple upstream ports, effectively making it a KVM switch without external switch button.

Altough monitor vendors provide propriatary software to switch inputs, it is often not possible to use it on Linux/MacOS, or to switch multiple monitors at once, or is generally ugly/buggy/bloatware.

This utility is efficient, cross-platform solution to switch up to 6 monitors at once, up to 4 different inputs per monitor with respective key combinations per input.

Assuming keyboard/mouse are connected via monitor's USB hub to achieve full KVM capability, this tool is supposed to be installed on all computers that could be connected to these monitors, since once the app switches inputs to other PC, pressing combo to revert will be now executed on that target PC.

Platforms supported

The app should function on MacOS (Intel Macs only), Windows, and Linux.

NOTE: Display Switch is currently not working on M1 Macs: M1 series SoC support in ddc-macos-rs is planned but is not implemented yet.

NOTE: Running on Linux requires additional packages, install via: sudo apt install libxi-dev xorg-dev

Configuration

The configuration is pretty similar on all platforms:

On MacOS: the configuration file is expected in ~/Library/Preferences/display-switch-keycombo.ini
On Windows: the configuration file is expected in %APPDATA%\display-switch-keycombo\display-switch-keycombo.ini
On Linux: the configuration file is expected in $XDG_CONFIG_HOME/display-switch-keycombo/display-switch-keycombo.ini or ~/.config/display-switch-keycombo/display-switch-keycombo.ini

Configuration file settings:

combo_a = ShiftLeft ControlLeft KeyM
combo_b = ShiftLeft ControlLeft Comma
input_a = "DisplayPort1"
input_b = "Hdmi2"

Paramters are:

• combo_a ... combo_d are space-separated key combinations to switch to respective input. Supported keys are listed in KEYS.md file
• input_a ... input_d are which monitor input to switch to, when respective key combination is detected. Supported values are Hdmi1, Hdmi2, DisplayPort1, DisplayPort2, Dvi1, Dvi2, Vga1. If your monitor has an USB-C port, it's usually reported as DisplayPort2. Input can also be specified as a "raw" decimal or hexadecimal value: on_usb_connect = 0x10
• input_a_execute ... input_d_execute are optional commands to run when respective key combination is detected. See below for details.

Different inputs on different monitors

display-switch-keycombo supports per-monitor configuration: add one or more monitor-specific configuration sections to set monitor-specific inputs. For example:

combo_a = ShiftLeft ControlLeft KeyM
combo_b = ShiftLeft ControlLeft Comma

[monitor1]
monitor_id = "U3419W"
input_a = "DisplayPort1"
input_b = "Hdmi2"

[monitor2]
monitor_id = "P2418D"
input_a = "DisplayPort1"
input_b = "Hdmi1"

monitor_id specifies a case-insensitive substring to match against the monitor ID. For example, 'U3419W' would match DELL U3419W S/N 1144206897 monitor ID. If more than one section has a match, a first one will be used. input_a ... input_d (if defined) take precedence over global defaults.

Running external commands

display-switch-keycombo supports running external commands upon executing key combination. This configuration can be global (runs every time specified combo is pressed) or per-monitor (runs only when a given monitor is being switched):

input_a = "Hdmi1"
input_b = "DisplayPort2"
input_a_execute = "echo connected"
input_b_execute = "echo disconnected"

[monitor1]
monitor_id="foobar"
input_a_execute = "echo usb connected, monitor 'foobar' being switched"
input_b_execute = "'c:\\program files\\my app.exe' --parameter"

Notes:

1. External applications are executed as the same user that started display-switch-keycombo.
2. This program supports splitting supplied configuration into application name and parameters, but no other shell features are supported.
3. If the application path contains spaces, surround the full file path with single quotes.
4. On Windows, escape the backslashes (replace \ with \, see the example above).

Logging

• On MacOS: the log file is written to /Users/USERNAME/Library/Logs/display-switch-keycombo/display-switch-keycombo.log
• On Windows: the log file is written to %LOCALAPPDATA%\display-switch-keycombo\display-switch-keycombo.log
• On Linux: The log file is written to $XDG_DATA_HOME/display-switch-keycombo/display-switch-keycombo.log or ~/.local/share/display-switch-keycombo/display-switch-keycombo.log

Building from source

Windows

Install Rust, then do cargo build --release

MacOS

Install Xcode, install Rust, then do cargo build --release

Linux

Install Rust, then do cargo build --release

Running on startup

Windows

Copy display_switch_keycombo.exe from target\release (where it was built in the previous step) to %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup.

MacOS

  # Get your INI file in order! (see above)
  cp target/release/display_switch_keycombo /usr/local/bin/
  cp dev.haim.display-switch-keycombo.daemon.plist ~/Library/LaunchAgents/
  launchctl load ~/Library/LaunchAgents/dev.haim.display-switch-keycombo.daemon.plist

Linux

Copy built executable:

  cp target/release/display_switch_keycombo /usr/local/bin/

Enable read/write access to i2c devices for users in i2c group. Run as root :

groupadd i2c
echo 'KERNEL=="i2c-[0-9]*", GROUP="i2c"' >> /etc/udev/rules.d/10-local_i2c_group.rules
udevadm control --reload-rules && udevadm trigger

Then add your user to the i2c group :

sudo usermod -aG i2c $(whoami)

Create a systemd unit file in your user directory (/home/$USER/.config/systemd/user/display-switch-keycombo.service) with contents

[Unit]
Description=Display switch via key combo

[Service]
ExecStart=/usr/local/bin/display_switch_keycombo
Type=simple
StandardOutput=journal
Restart=always

[Install]
WantedBy=default.target

Create the config file at /home/$USER/.config/display-switch-keycombo/display-switch-keycombo.ini. Then enable the service with

systemctl --user daemon-reload
systemctl --user enable display-switch-keycombo.service
systemctl --user start display-switch-keycombo.service