Devil for Win, Penguin for Linux. SSI Question

mrl · 05-29-2001, 05:17 PM

Hi Folks,

I'm trying to learn SSI on apache at the moment for fun and would like the browser to display an icon/graphic depending on the users OS

I thought I could use SSI to tell me the browser and OS by using



resulting in..

Mozilla/4.0 (compatible; MSIE 5.0; Linux 2.4.2-2 i686) Opera 5.0 [en]

Instead of telling the user which browser they are using I would like to dispay a seperate image for Linux and windoze users (penguin and devil).

I geuss I would have to character match to find 'Linux' or windows in the HTTP_USER_AGENT variable and then do an If / else thing to select the image.

Could anybody point me in the right direction or suggest how I could do this in bash or perl.

this is what I have come up with so far, it is VERY untidy and does not work

but is the product of an evening playing.
I have just used text to experiment with but will use images when / if it does work

<HTML>

<HEAD>

<TITLE>Stupid Page</TITLE>

</HEAD>

<body>

































<B>Good Stuff, Linux is so so kewl!<B>



<B>Prepare to Blue Screen, your using Windoze</B>



Hmm, Must be a Mac or something



</body>

</HTML>

Cheers

Mike

[Edited by mrl on 05-29-2001 at 07:09 PM]

doodah · 05-29-2001, 06:21 PM

if you know perl...write a block like this for a cgi...

Code:

#!/usr/bin/perl

$browserIs = $ENV{'HTTP_USER_AGENT'}

if($browserIs =~ m/MSIE/gi){
print "LOCATION_OF_DEVIL_PIC";
}
else{
print "LOCATION_OF_PENGUIN_PIC";
}

the print will print the path of the pic, just as if you were hardcoding it in the html file.. ex.

<img src="">

you will want to change that regex to detect win** or linux or whatever 'HTTP_USER_AGENT' prints for different os's...

doodah · 05-29-2001, 06:32 PM

hey you changed that while i was writing! if you want to have different things printed all throughout the page, i would just script the entire page in perl.. perl would be a lot less expensive on the performance end(and alot prettier!).. if you have any questions on perl jsut ask.....

mrl · 05-30-2001, 07:47 PM

Hi Doodah

That's just like me to change things in the middle of something

Quote:

. if you have any questions on perl just ask.....

You may regret that!! I have been trying to learn Perl for a while (that is what got me in to Linux) but I am not mathematical or good with computers (I'm a Nurse/Medic IRL, so this is for Kicks) - this character matching has me stumped. I have read a fair bit on it and can 'read' simple scripts to a certain extent but can not write anything yet. The problem I have is I can not translate the character matching code at all.
This has stopped me learning more about perl, I just need to get a handle on it (which is why I started with the SSI thing).

if($browserIs =~ m/MSIE/gi)

i understand that this is looking to match 'MSIE' string. Could you explain what the other characters mean and how I could apply these to extract the OS.

Any help greatly appreciated.

Cheers

Mike

doodah · 05-31-2001, 07:29 PM

Code:

if($browserIs =~ m/MSIE/gi)

im assuming you know the if() and that $browserIs is a scalar...

the '=~' is the comparison operator for regexes(regular expressions)... in this case it says

look in $browserIs for-(whatever is on the other side of =~)

the 'm/MSIE/gi' bit says to

MATCH the expression 'MSIE' in whatever is on the other side of '=~'... the 'gi' means global and (case)insensitive... if it finds it, the if() gets a 1 if not, a 0...(well not actually a 1 or 0, but it works for this example)

to get the os you will need to test to see what 'HTTP_USER_AGENT' returns for different os's.. cuz i dont know... but for example if it returned 'linux' just do a block like...

Code:

#!/usr/bin/perl

$browserIs = $ENV{'HTTP_USER_AGENT'}

if($browserIs =~ m/linux/gi){
print "LOCATION_OF_PENGUIN_PIC";
}
else{
print "LOCATION_OF_DEVIL_PIC";

}

this is pretty simple use of regex's, because you know basically what 'HTTP_USER_AGENT' is returning always... but it can get ALOT more complex for other operations...i will answer any questions, no prob!.. but perl is deep, and powerful, i first learned from the 'camel book'(O'Reilly, Programming Perl)... i would recommend that if you are serious about learning Perl... but dont hesitate to ask....