New to CGI: Couple of questions 2

[solepixel]

Hi. I am new to CGI and am just starting out trying a few things. I am a PHP/MySQL developer and am comfortable writing XHTML, XML, CSS, JavaScript, and ASP.NET VB. I know pretty much nothing of CGI and would like to learn a bit more. Here are a couple of questions I have to start out with:

In a project I'm working on, there's some code that looks like this:

if [[ -x /SOME/DIR/SOMETHING ]];then
 /SOME/DIR/SOMETHING INTR001
else
 SOMETHING INTR001
fi

what exactly is going on here? Is this if statement referencing some file, performing a command, what? what does the [[ ]] mean? why the ";"? what is the "fi" at the end?

Main reason I'm asking about this in particular, because I've looked on the server and there is no file located in /SOME/DIR/ called SOMETHING. There aren't any files on the whole server called SOMETHING. What's this code doing?


Another question I have is I tried this to perform a redirect (something more consistent than "meta refresh" or a javascript redirect:

#!/usr/bin/perl
my $URL = "/cgi-bin/main.cgi?INIT";

print "Location: $URL\n\n";

however, I get the message:

Method Not Allowed
An error has occurred.

I tried putting this file in the "CGI-BIN" and I get:

Server Error
This server has encountered an internal error which prevents it from fulfilling your request. The most likely cause is a misconfiguration. Please ask the administrator to look for messages in the server's error log.

Is this because of some setting I have somewhere on the server that restricts redirects? Also, why won't cgi files work outside of /cgi-bin/? Is that also some kind of setting? Is it possible to get CGI to work outside the CGI-BIN? Is there some other way of performing a server-side redirect on a server like this?

I am curious to learn about this stuff and hoped someone could help. Thanks.

 

[feherke]

Hi

what exactly is going on here?

Your first code seems to be a shell script. Probably either [tt]bash[/tt] or [tt]ksh[/tt]. For more about shell scripts read the given shell's man page. Or ask in forum822.

Is this if statement referencing some file, performing a command, what?

If the specified file exists and is executable, executes it by referencing it with full path, otherwise executes it just hoping it is [small]a)[/small] an alias, [small]b)[/small] a function, [small]cd)[/small] shell built-in or [small]d)[/small] an executable somewhere on the [tt]PATH[/tt].

what does the [[ ]] mean? why the ";"? what is the "fi" at the end?

[tt][[ ]][/tt] - conditional expression with pattern matching
[tt];[/tt] - the [tt]if[/tt] and [tt]then[/tt] keywords should be in separate lines but the author preferred to write them on the same line
[tt]fi[/tt] - closing pair of [tt]if[/tt]

Is this because of some setting I have somewhere on the server that restricts redirects?

Usually none, but may depend on the web server you use. Your [tt]perl[/tt] code works for me. Just the /cgi-bin/main.cgi directly works for you ?

Also, why won't cgi files work outside of /cgi-bin/?

Usually that is the default, but may depend on the web server you use. It is mainly for security reasons.

Is that also some kind of setting?

Usually there is, but may depend on the web server you use. Maybe try to post in your web server's forum.

Is there some other way of performing a server-side redirect on a server like this?

Strange wording. Let us call it simply HTTP redirect, because are involved both the server and the client. Well, while you asked for, yes. You can use [tt]Refresh[/tt] as an ugly and stupid alternative.

Feherke.

http://rootshell.be/~feherke/

 

[solepixel]

Wow thank you so much for helping me with this information. thanks for being so detailed in your response. I will check out the UNIX and web server forums to hopefully come up with a solution to my situation.

 

[KevinADC]

that deserves at least two stars

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- Kevin, perl coder unexceptional!