Dice in shell#

Today I was borrowing a board game from the lending library at Emerald City Comicon and it was missing its dice. We could have gotten some physical dice somewhere, but instead we decided to use the materials we had on hand. The people I was playing with agreed that we did not want to drain our phone batteries by using a dice app on our phones, but I had a laptop with me. So I wrote a dice app for the shell:

while true
do
    reset
    seq 1 6 | shuf -n1
    seq 1 6 | shuf -n1
    read
done

This rolls two six-sided dice every time you hit enter and clears the screen before showing the result using reset.

Better use of shuf#

shuf can generate the number sequence itself without using seq:

$ shuf -n1 --input-range=1-6

I didn't use that feature because I wanted to write the script quickly without reading man pages and didn't remember how to do it from memory.

Accepting any key#

read_keypress.sh:

#!/bin/sh

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

This script uses stty to set the terminal to raw mode (instead of using GNU Readline) and reads the next keypress before restoring the terminal to its previous state. Effectively it waits for a single keypress like read waits for a line to be typed.