bash if shift-key pressed

I had to write a custom bash launch script for a local machine, but wanted it to do one thing if the shift-key was pressed and another thing if it was not.

After searching, i found that bash is NOT capable of such a thing. However, there was a short and simpe C implementation found here: https://forums.gentoo.org/viewtopic-p-2455159.html#2455159

So after compiling the code (gcc shift_state.c -o shift_state ; chmod +x shift_state) and explicitly running it under sudo (required to access /dev/console), i found it did exactly what was needed.

So the only problem remaining was i didn’t want to run my bash script with sudo. To circumvent such, i ran sudo visudo and added the line myusername ALL=(ALL) NOPASSWD: /home/myusername/scripts/shift_state which would allow me to run sudo ~/scripts/shift_state without entering my password.

Subsequently, it was easy to implement a bash script as needed.

Code:

	#include <sys/ioctl.h>
	#include <asm/ioctls.h>
	#include <stdio.h>
	#include <fcntl.h>
	// code by "dma" via https://forums.gentoo.org/viewtopic-p-2455159.html#2455159
	int main(int argc, char *argv[]) {
	int fd;
	char shift_state;
	fd = open("/dev/console", O_RDWR);
	/*
	* From console_ioctl:
	* TIOCLINUX, subcode=6
	* argp points to a char which is set to the value of the kernel
	* variable shift_state. (Since 1.1.32.)
	*/
	shift_state = 6;
	ioctl(fd, TIOCLINUX, &shift_state);
	printf("shift_state = %i\n", (int)shift_state);
	close(fd);
	return shift_state;
	}

view raw shift_state.c hosted with ❤ by GitHub

	#!/bin/bash
	shift_state=$(sudo ~/path/to/shift_state)
	if (( $shift_state )) ; then
	echo "shift-key active"
	else
	echo "shift-key not active"
	fi

view raw somescript.sh hosted with ❤ by GitHub

But wait, there's more!

Such could also be used to customize your XFCE Panel-based launch-bar. (Or any launch-bar for that matter.) For instance, In the past, I've created a panel item for Sublimetext. This is a "Launcher" item with two sublimetext commands, one launches and another launches with the -n parameter for a new window. However, it looks ugly and a bit cumbersome to launch:

With the shift_state method, I have replaced the Launcher commands with a single command: bash -c "if ! (( $(sudo ~/scripts/shift_state) )) ; then /opt/sublime_text/sublime_text %F ; else /opt/sublime_text/sublime_text -n %F ; fi". Now it looks better without a secondary command-arrow, and when I shift-click to launch, it provides me the same function in a quicker workflow way.

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As Always, Good Luck! You can thank me with bitcoin.   

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