The problem#

For certain applications it can be useful to get many quick responses from the computer, so we would like it to react to individual keypresses instead of requiring an entire command to be typed out and confirmed by pressing Enter. While this is a common feature of GUI and TUI toolkits (e.g., ncurses), it can also be useful for very lightweight inactive experiences written as simple shell scripts.

The solution#

read_keypress.sh will wait for the next keypress and return it as a string:

#!/bin/sh

STTY=$(stty --save)
stty raw -echo
SEL=$(dd if=/dev/tty bs=1k count=1 2>/dev/null)
stty "$STTY"
echo -n "$SEL"

The details#

The problem#

I have my window manager set to not focus new windows because I dislike having a new window pop up while typing and having the keystrokes surprisingly sent to the new window instead of the one I thought I was typing in. While this is usually what I want, this does mean extra clicks when I did mean to open the new window.

This is particularly bad for xfce4-appfinder (or any other application launcher), since the purpose to be able to set a global keyboard shortcut like Super+Space so you can press that combination and quickly type in the application or action you want (or, even better, type just the first few characters of its name). And since it's being intentionally launched by a keyboard shortcut, there's no real concern of it grabbing keyboard focus unexpectedly.

The solution#

Put the following script in a file appfinder-and-focus.sh and set the keyboard shortcut to run it instead of just running xfce4-appfinder directly:

#!/usr/bin/bash
(xprop -spy -root _NET_CLIENT_LIST | stdbuf -oL tail -n +2 |
  while read -r line
  do
    winid="${line/#*, /}"
    if [[ $(xdotool getwindowname "$winid") == \
        "Application Finder" ]]
    then
      xdotool windowactivate "$winid"
    fi
  done) 2>/dev/null &
xfce4-appfinder &

# Wait for window to appear, then kill xprop.
xdotool search --sync --name "Application Finder" >/dev/null
pkill -P "$(jobs -p %1)"

The details#

Most desktop environments provide options for customizing keyboard shortcuts. In XFCE, there's settings panels for both for window manager shortcuts and application shortcuts. While the term "application shortcuts" suggests using them for launching applications, and many keyboards do have special keys for launching a music player or a calculator that I do have set up, I don't find myself using those much. I have buttons on my panel for applications that I launch often; if I'm going to be clicking away into a new application, I don't find clicking on the panel to be an additional inconvenience.

On the other hand, "application shortcuts" can be used for launching arbitrary scripts, including ones don't involve switching contexts.

Keys to use#

Many keyboards have extra keys intended for global commands labeled with various symbols. If you have them, you can be creative about what you want them to mean and even combine them with modifiers (Shift, Ctrl, etc.) to get more inputs. On the other hand, if you have a more traditional keyboard layout (which is likely the case on a laptop), your choices are more limited. To avoid confusion, it's generally best to use the Windows key (usually called the Super key in Linux) for global shortcuts as it is not usually used for anything else.

Shortcut ideas#