Displaying content in real time

[dnszero]

Is there any way to display the output of a shell script (or a php function) while it is being generated?

For example, if i have the following shell script:

#!/bin/sh
echo "."
sleep 1
echo ".."
sleep 1
echo "..."
sleep 1

Can i have a php page that displays each line of output as it is generated (instead of after the script finishes)?

[suzuki]

make the shellscript something like

#!/bin/sh

echo "<p>"
echo "."
echo "</p>"
sleep 1
echo "<p>"
echo ".."
echo "</p>"
sleep 1
echo "<p>"
echo "..."
echo "</p>"
sleep 1

<p> is just one of many tags you can use for this purpose of course, think about table columns, rows,...

[dnszero]

Actually, I'm not concerned with format...just with the timing.

I would like the user to see each line as it is generated rather than having to wait for the entire script to run before any output is displayed, i.e., if you the script from the shell you will a series of dots with a 1 second delay before the next series of dots. The problem is that when I output it to a web page, the entire script has to run before any data is displayed.

[Anon]

I don't know if this helps any, but to do what you are asking you need to be able to open up a kind of session between the server and the client. This of course if difficult due to the stateless nature of the HTPPS protocol.

However, I have seen something like this done before. To be more exact, I have read about it. In the book "Web Application Development with PHP 4.0" by Ratschiller and Gerken they use a techniche to have live IRC chat over a web page. It involves keeping a connection open by using an unsupported http protocol specification whereby you "stream" html. That's about all the detail I can go into off of the top of my head. The program itself is available at www.phpwizard.net. I suggest heading over there and taking a look at how they pulled this off. Hope that helps.

Alan

[rrijnders]

In PHP, you can use the flush() function after each line to send buffered data to the browser:

print "<p>hello</p>";
flush();
sleep(5);
print "<p>world!</p>";
flush();

The <p></p> tags are necessary because most browsers won't render the information (even if it has been sent) until they have a completed container.

HTH

-- Rich Rijnders
-- Irvine, CA US

[suzuki]

I don't use those <p> for formatting in this case, just to have closed containers, like richard a. rijnders explains later in this thread...

[suzuki]

hmmmz, from manual:

passthru("test.sh");

maybe that's what you're looking for?

[dnszero]

OK, I tried the <P></P> tags around each line of output but with no success. Your (and jeffry's) explanation makes sense now in the context of containers. But maybe that's why it still doesn't work...the browser seems to be waiting for the tag before rendering any of the page.

Perhaps, Alan's suggestion of streaming html is the way to attack the problem?

Or is there a javascript solution perhaps?

[josephferris]

Dave,

I remember seeing something like this in a Perl Script a long time ago. To the best of my knowledge, it is done with a multipart/mixed type. The best reference that I could find for you is:

http://home.netscape.com/assist/net_sites/pushpull.html

It is pretty much the latter half of the document that might be of some help.

HTH,

Joseph

[dnszero]

It turns out that the client was buffering the data (both msie and netscape) and that my script wasn't producing enough data to fill the buffer.

So...I included several lines of html comments, ala, "<!-- blah blah blah -->", and used system("myshorttestscript.sh"). And that's all it took. I haven't calculated the mininum number of "blah blah blah"s necessary but about 7 lines worth seemed to work fine in both msie and netscape.

Thanks for all the help.