xwinid

#!/bin/sh
# (c) Copyright 2017 Jonathan Simmonds
# Tiny wrapper on top of xwininfo to grab just the Window ID in decimal.
# This is only really useful if you are scripting a windowing utility as
# xwininfo does not offer a machine readable output form.
set -e

usage()
{
    echo "usage: xwinid [window-name]"
    echo ""
    echo "Tiny wrapper on top of xwininfo to grab just the Window ID in decimal."
    echo ""
    echo "positional arguments:"
    echo "  window-name     Optional name of the window to query. If ommitted the"
    echo "                  cursor will be used to select the window to query."
    echo ""
    echo "optional arguments:"
    echo "  -h, --help  Print this message and exit."
    exit 1
}

# Script variables
XWINARGS=""
SCRIPT_DIR=$(readlink -f "$0" | xargs dirname)

# Handle command line
while [ $# -gt 0 ]; do
    command_line_arg="$1"
    shift
    case "$command_line_arg" in
        -h)
            usage
            ;;
        --help)
            usage
            ;;
        *)
            XWINARGS="-name $command_line_arg"
            ;;
    esac
done

# Actual implementation
XID=$(xwininfo -int ${XWINARGS} | grep -Po "Window id: [0-9]+" | grep -Po "[0-9]+$")
echo $XID