shortcutd

Launch commands when pressing keys combinations. Key features:

• Reads Kernel input device nodes directly so there is no need of any graphical environment and works whatever the launched software stack.

• Support for blocking and non blocking commands spawns.

• Resilient to keyboard hotplugs. You can plug your keyboard only when needed. There is no need for it to be plugged when shortcutd is launched.

shortcutd is a daemon written in NodeJS. It works on Linux and has been designed to execute low level/administrative commands like systemctl start some.service using keyboard shortcuts, on headless or embedded systems for example but is obviously not limited to.

Installation

$ npm install -g shortcutd

Configuration

shortcutd is configured via a JSON configuration file. Here is a simple working configuration file:

{
    "device": "/dev/input/by-id/usb-Logitech_USB_Keyboard-event-kbd",
    "shortcuts": [{
        "keys": "KEY_LEFTCTRL+KEY_LEFTALT+KEY_1",
        "blocking": true,
        "command": "echo Hello World!; sleep 5" 
    }, {
        "keys": "KEY_LEFTCTRL+KEY_LEFTALT+KEY_2",
        "blocking": false,
        "command": "echo Hello World!"
    }, {
        "keys": "KEY_LEFTCTRL+KEY_LEFTALT+KEY_2",
        "blocking": false,
        "release": true,
        "command": "echo key released"
    }]
}

Device node

The input device node path of the keyboard must be specified via the device property. Input device nodes are generaly located in /dev/input/. If you are not sure which device node corresponds to the keyboard you want to use — on some systems they are simply labeled event[0-9]+ — you can try them one by one by launching shortcutd in verbose mode and see if pressed keys are displayed to your terminal (see Usage below).

About (un|re)plug resilience: It is important for shortcutd to be able to detect your keyboard when (re)plugged that the device node has the same path. It is sometimes the case, like links inside the /dev/input/by-id subdirectory. If not, this can be configured nowadays on Linux systems through udev rules.

Device nodes are only readable by root by default. This can be configured with udev rules too.

Shortcuts configuration

Shortcuts are configured inside the shortcuts property. Each shortcut configuration object is defined by theses three properties:

keys

Define the keys combinations that will spawn the command when pressed. Each key code is separated by a + char. You can launch shortcutd in verbose mode without any shortcuts configured to print the codes of the keys in your terminal when they are pressed.

blocking

Tell shortcutd to wait (blocking) for the command to finish once spawned before allowing the user to spawn it again.

command

The command to spawn when the keys combinations are pressed

release

Specify the command to be triggered on key release instead of keypress.

Usage

$ shortcutd [-v] <config-file>

-v option enables verbose mode. Additionnaly to common verbose logs, every key press/release events are logged. This is especially useful to test device nodes and to get the name of the key codes.

shortcutd does not daemonize itself but can easily be launched as a systemd service. Simply put the following into a systemd service configuration file:

[Unit]
Description=Shortcutd

[Install]
WantedBy=multi-user.target

[Service]
ExecStart=/usr/bin/shortcutd /usr/local/etc/shortcutd.json

Known issues and improvments

• shortcutd could be able to read input device events of others devices than keyboards (mouses, joysticks..) but only keyboard kernel event codes have been implemented.

• Only english key mappings are supported. It means pressing a a char using an azerty keyboard is recorded as a q char. If key codes are configured as appearing in verbose mode this should not be an issue.

Contributions

... are welcome :)