Action to run script with dialog box shown only once.

Another option is to call the script with the SHIFT key pressed then you can use..

if (ScriptUI.environment.keyboardState.shiftKey){

    // UI goes here

    }

//rest of code

Then the UI will only be called the first time.

You can use get_run_counter() set_run_counter() or _get_run_counter() _set_run_counter() functions to determine the number of script starts since the start of the photoshop.

///////////////

var options_name = "My Options";

alert (get_run_counter())

inc_run_counter();

alert (_get_run_counter())

_inc_run_counter();

////////////////////////////////////////////////////////////////////////////////////////////

function get_run_counter()

    {

    var d = null;

    try { d = app.getCustomOptions(options_name); } catch(e) { d = null; }

    if (!d) return 0;

    return d.getInteger(0);

    }

////////////////////////////////////////////////////////////////////////////////////////////

function inc_run_counter()

    {

    var cnt = get_run_counter();

    var d = new ActionDescriptor();

    d.putInteger( 0, cnt+1);

    app.putCustomOptions(options_name, d, true);

    }

////////////////////////////////////////////////////////////////////////////////////////////

function _get_run_counter()

    {

    var cnt = $.getenv(options_name);

    if (cnt == null || cnt == undefined) return 0;

    return Number(cnt);

    }

////////////////////////////////////////////////////////////////////////////////////////////

function _inc_run_counter()

    {

    var cnt = _get_run_counter();

    ++cnt;

    $.setenv(options_name, cnt.toFixed(0));

    }