How to launch default browser from bash script

How do I launch the default Web browser from within a script? In the below script, the browser opens when the script is successfully run as an executable shell script:

#!/bin/bash
cd $1
php -S 127.0.0.1:5000
for f in *.html; do cp -- "$f" "${f%.html}.php"; done
x-www-browser http://127.0.0.1:5000/index.php

However, in this longer version with Kdialog UI, everything executes correctly (the files are created and the server starts in the chosen directory) except for the launching of the browser

#!/bin/bash
`kdialog --yesno "HTML Files created, make PHP?"`
    if [ $? = 1 ]; then
    `kdialog --sorry "No PHP files created"`
    exit 1 
    fi;
    if [ $? = 0 ]; then
    `kdialog --warningcontinuecancel "Select HTML directory"`
        if [ $? = 0 ]; then
        cd `kdialog --getexistingdirectory`
        #exit 1
        else
        `kdialog --warningyesno "You didn't select a directory. \
        <br>Yes to choose, No to cancel."`
        if [ $? = 0 ]; then
        cd `kdialog --getexistingdirectory`
        exit 1
        fi;
        fi;
    fi;
        if [ $? = 0 ]; then
PORTNO=`kdialog --title "Port Number" --inputbox "Port: (Eg 7000)"`
        fi;
         if [ $? = 1 ]; then
         `kdialog --warningyesno "You didn't enter a port. <br>Yes to coose, No to cancel."`
         if [ $? = 0 ]; then
         PORTNO=`kdialog --title "Port Number" --inputbox "Port: (Eg 7000)"`
         fi;
         fi;
         if [ $? = 0 ]; then
COPYORNEW=`kdialog --radiolist "Copy HTML or make new files?:" 1 "Copy \
HTML files" off 2 "Rename HTML files" off`
         else
         exit 1
        fi;
    if [ "$COPYORNEW" = 1 ]; then
    php -S 127.0.0.1:$PORTNO
    for f in *.html; do cp -- "$f" "${f%.html}.php"; done
    #x-www-browser http://127.0.0.1:$PORTNO
    exit 1
    elif [ "$COPYORNEW" = 2 ]; then
    php -S 127.0.0.1:$PORTNO
    for f in *.html; do mv -- "$f" "${f%.html}.php"; done
    #x-www-browser http://127.0.0.1:$PORTNO
    exit 1
    fi;
URL="http://127.0.0.1:$PORTNO"; xdg-open $URL || sensible-browser $URL || x-www-browser $URL || gnome-open $URL

In both the short- and long-form versions, the command to open the browser is the last.

Я попробовал последнюю строку в оболочке, и это сработало. Смысл. дал значение PORTNO и выполнил последнюю строку.

#!/бин/баш
ПОРТНОМ=5000
URL="http://127.0.0.1:$PORTNO"; xdg-открыть $URL || разумный браузер $URL || x-www-браузер $URL || гном-открыть $URL

он работает в моей системе (рабочий стол 20.04.2)
логика в порядке? кажется, что @steeldriver прав.

С Уважением.