You cannot embed shell scripts into HTML, at least not without programming your own apache module to do so.
When your shell script is called it has to provide all the HTML output by itself.
Other possibility is to embed PHP scripts within the HTML page and call from within PHP the shell script like:
system (". my_script.sh");
The same for 'crontab -l': open a pipe in PHP from within a table definition.
It also works the other way around: call PHP routines from within your shell script to do the HTML output and mix it with Bash statement. PHP must be CLI-enabled for this.
An excellent opportunity to do a lot of tests and waste a lot of time.
Is there any specific reason why you want to use shell scripting on a web server?
And don't forget the double linefeed after the HTTP header when producing HTML pages in shell scripts.
Xen in Hardy