UpdateController/SendUpdateCommand.sh

#!/bin/bash

fifo=""

read_config() {
    fifo_dir=$(cat "$1" | jq -r .fifo_dir)
    if [ -z "$fifo_dir" ]; then
        return 1 
    fi

    fifo=$(cat "$1" | jq -r .fifo)
    if [ -z "$fifo" ]; then 
        return 1
    fi
    
    fifo="${fifo_dir}/$fifo"
    return 0
}

if [ $# -ne 1 ] ; then
    echo "Usage: $0 filename"  
    exit 1 
else
    if read_config "$1" ; then
        if [[ ! -p $fifo ]]; then
            echo "Reader not running on $fifo"
            exit 1
        fi
        echo "Reader running on $fifo: update"
        echo "update" >$fifo
        exit 0
    fi
fi