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CGI script not executing every page visit

Answer 1

+1 A:

You need to tell the browser (and possible proxies) to disable caching of the file with the appropriate HTTP headers:

Pragma-directive: no-cache
Cache-directive: no-cache
Cache-control: no-cache
Pragma: no-cache
Expires: 0

Of course, you'll just add each these in your script like this:

printf "Pragma-directive: no-cache\r\n";

There's a fair bit of redundancy in these directives. All are probably not necessary, but it's good to make sure there's something all browsers and proxies out there understand.

Ville Laurikari 2009-08-04 13:38:33

Answer 2

+1 A:

This doesn't answer your question, so feel free to down vote, but you can make this much easier on yourself by doing:

#!/bin/bash

cat /myspecialdir/foo > /httpd/foo.html

printf "Location: /foo.html\n\n";

This sends a header to the browser telling it to redirect to /foo.html instead of having to load and parse the <meta> tags.

Edit: You should only send 1 \n at the end of each header. After the entire request, you send 2 of them, like this (broken out for clarity):

#!/bin/bash
cat /myspecialdir/foo > /httpd/foo.txt
printf "Pragma-directive: no-cache\n";
printf "Cache-directive: no-cache\n";
printf "Cache-control: no-cache\n";
printf "Pragma: no-cache\n";
printf "Expires: 0\n";
printf "Location: /foo.txt\n";
printf "\n";

(Also note that the Content-Type header isn't included)

Sean Bright 2009-08-04 13:38:44

Sorry, Sean, but that doesn't redirect. All that does is print "Location: /foo.html" in the browser. Am I missing something?The new script is:#!/bin/ashcat /myspecialdir/foo > /httpd/foo.txtprintf "Location: /foo.txt\r\n";printf "Pragma-directive: no-cache\r\n"printf "Cache-directive: no-cache\r\n"printf "Cache-control: no-cache\r\n"printf "Pragma: no-cache\r\n"printf "Expires: 0\r\n"

Coleman 2009-08-04 14:35:55

See my edit for details.

Sean Bright 2009-08-04 16:06:22

Thanks for the clarification, Sean. It looks like the server I'm using (httpd from an older BusyBox) breaks this though because it automatically sends the Content-type: text/plain header which prevents my script from sending headers. So, unforutnately, I have to use META tags.

Coleman 2009-08-04 16:24:18

I've marked this as the answer because of Sean's follow-up. Thanks!!!

Coleman 2009-08-04 16:25:43

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CGI script not executing every page visit

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