How to obtain values of all Apache's mod_rewrite environment variables, without PHP? - apache

Question

I have an Apache instance but without PHP (almost all the SO answers I found for this are PHP-specific). In fact it's mostly serving static content.
I'm working on some mod_rewrite redirections and I'd like to know the exact values of all environment variables.
Those pages list Apache's available env variables and example values
http://www.zytrax.com/tech/web/env_var.htm
https://www.cheatography.com/davechild/cheat-sheets/mod-rewrite/
however I'd like to see the exact values coming from my requests, to facilitate working on my rewrite rules.
What would be the easiest way to get all the Apache environment values? (without installing PHP on it).
As a poor man's debugging, I know I can get values one by one by defining some example rewrites like this
RewriteRule ^/test.htm http://localhost/test2.htm?SERVER_NAME=%{SERVER_NAME} [R,L,NC]
and then hitting http://localhost/test.htm and observing the redirect, but this is not a really good solution.
Is there a better way to learn about all the environment, not specific to any particular language like PHP?

Answer 1

You can obtain the values of all Apache environment variables with Perl. The standard Apache distribution still bundles the good old printenv.pl CGI script. Here's what mine (Apache/2.4 on Windows) looks like:
#!D:/programs/perl/bin/perl.exe
#
# To permit this cgi, replace # on the first line above with the
# appropriate #!/path/to/perl shebang, and on Unix / Linux also
# set this script executable with chmod 755.
#
# ***** !!! WARNING !!! *****
# This script echoes the server environment variables and therefore
# leaks information - so NEVER use it in a live server environment!
# It is provided only for testing purpose.
# Also note that it is subject to cross site scripting attacks on
# MS IE and any other browser which fails to honor RFC2616.
##
## printenv -- demo CGI program which just prints its environment
##
use strict;
use warnings;
print "Content-type: text/plain; charset=iso-8859-1\n\n";
foreach my $var (sort(keys(%ENV))) {
my $val = $ENV{$var};
$val =~ s|\n|\\n|g;
$val =~ s|"|\\"|g;
print "${var}=\"${val}\"\n";
}
Of course:
You need Perl installed
Apache administrator will typically not enable the default /cgi-bin directory
Other that using a program, you're out of luck. I'm not aware of any builtin Apache module that reports ENV variables (not even mod_info).