Toggle touchpad on laptop

toggle-touchpad.sh

#!/bin/bash

stderr() { cat <<< "$@" 1>&2; }

toggle_xinput_device()
{
    declare -r -a device_filters=("$@")

    if [[ ${#device_filters[*]} -eq 0 ]]; then
        stderr "No filters provided."
        return 1
    fi

    local xinput_output
    if ! xinput_output="$(xinput)"; then
        stderr "Failed to get xinput"
        return 1
    fi

    local lines rest="${xinput_output}"
    for filter in "${device_filters[@]}"; do
        if ! rest="$(grep -i "${filter}" <<< "${rest}")"; then
            stderr "Failed find ${filter} in xinput output"
            return 1
        fi
    done

    if [[ "$(wc -l <<< "${rest}")" != 1 ]]; then
        stderr "Too many devices found"
        stderr "${rest}"
        return 1
    fi
    local touchpad_line="${rest}"

    declare id
    id="$(sed -e 's/^[^=]*id=//' -e 's/[^0-9].*//' <<< "${touchpad_line}")"
    if [[ -z $id ]]; then
        stderr "Failed find device ID in xinput output"
        return 1
    fi

    local enabled
    enabled="$(xinput list-props "${id}" | awk '/Device Enabled/ {print $NF}')"
    if [[ $enabled = "1" ]]; then
        xinput --disable "${id}"
    elif [[ $enabled = "0" ]]; then
        xinput --enable "${id}"
    else
        stderr "Unknown enabled state: $enabled"
        return 1
    fi
}

main()
{
    toggle_xinput_device 'pointer' 'Synaptics TouchPad'
}

[[ "${BASH_SOURCE[0]}" == "${0}" ]] && main "$@"