Server Side Includes (SSI)
Echo Environment Variables

A number of environment variables can be used in #if and #echo statements, such as
<!--#echo var="HTTP_USER_AGENT" -->
which yields the browser you are using: CCBot/1.0 (+http://www.commoncrawl.org/bot.html)

These variables can be used in if/elif/else/endif statements, which allow you to construct conditional displays of information. The basic test is the comparison of two strings or a string and a unix egrep regular expression, the tests can be combined using the usual logical operations. See http://www.apache.org/docs/mod/mod_include.html#flowctrl for details.

Environment Variables displayed through echo:
DATE_GMT:   Friday, 10-Jul-2009 06:36:05 GMT
DATE_LOCAL:   Friday, 10-Jul-2009 02:36:05 EDT
DOCUMENT_NAME:   ssi-echo.shtml
DOCUMENT_URI:   /cwis/web/ssi-echo.shtml
LAST_MODIFIED:   Wednesday, 14-Nov-2001 16:51:12 EST
DOCUMENT_ROOT:   /afs/net.mit.edu/admin/www/root
DOCUMENT_PATH_INFO:   (none)
DOCUMENT_URI:   /cwis/web/ssi-echo.shtml
GATEWAY_INTERFACE:   CGI/1.1
HTTP_REFERER:   (none)
HTTPS:   (none)
HTTPS_CIPHER:   (none)
HTTPS_KEYSIZE:   (none)
HTTPS_SECRETKEYSIZE:   (none)
HTTP_ACCEPT:   Accept: text/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
HTTP_ACCEPT_CHARSET:   ISO-8859-1,utf-8;q=0.7,*;q=0.7
HTTP_ACCEPT_ENCODING:   gzip
HTTP_ACCEPT_LANGUAGE:   en-us,en;q=0.5
HTTP_CONNECTION:   close
HTTP_HOST:   web.mit.edu
HTTP_PRAGMA:   no-cache
HTTP_USER_AGENT:   CCBot/1.0 (+http://www.commoncrawl.org/bot.html)
PATH:   /usr/local/perl5/bin:/usr/local/sendmail/bin:/usr/local/mimedefang/bin:/usr/local/bind/bin:/usr/local/dcc/bin:/usr/local/uvscan:/usr/local/spamscreen/bin:/usr/athena/bin:/usr/athena/etc:/etc/athena:/usr/kerberos/bin:/usr/kerberos/sbin:/usr/sbin:/sbin:/bin/athena:/bin:/usr/bin:/etc:/usr/X11R6/bin
QUERY_STRING:  
QUERY_STRING_UNESCAPED:   (none)
REMOTE_ADDR:   38.103.63.61
REMOTE_PORT:   55542
REQUEST_METHOD:   GET
REQUEST_URI:   /cwis/web/ssi-echo.shtml
SCRIPT_FILENAME:   /afs/net.mit.edu/admin/www/root/afs/athena.mit.edu/org/c/cwis/web/ssi-echo.shtml
SCRIPT_NAME:   /cwis/web/ssi-echo.shtml
SERVER_ADMIN:   network@mit.edu
SERVER_NAME:   web.mit.edu
SERVER_PORT:   80
SERVER_PROTOCOL:   HTTP/1.1
SERVER_SOFTWARE:   Apache/1.3.41 (Unix) mod_ssl/2.8.31 OpenSSL/0.9.8j
SERVER_SIGNATURE:   <ADDRESS>Apache/1.3.41 Server at web.mit.edu Port 80</ADDRESS>
SSL_CIPHER:   (none)
SSL_CLIENT_C:   (none)
SSL_CLIENT_CN:   (none)
SSL_CLIENT_DN:   (none)
SSL_CLIENT_EMAIL:   (none)
SSL_CLIENT_I_C:   (none)
SSL_CLIENT_I_DN:   (none)
SSL_CLIENT_I_O:   (none)
SSL_CLIENT_I_OU:   (none)
SSL_CLIENT_I_ST:   (none)
SSL_CLIENT_O:   (none)
SSL_CLIENT_OU:   (none)
SSL_CLIENT_ST:   (none)
SSL_PROTOCOL_VERSION:   (none)
SSL_SERVER_C:   (none)
SSL_SERVER_CN:   (none)
SSL_SERVER_DN:   (none)
SSL_SERVER_I_C:   (none)
SSL_SERVER_I_CN:   (none)
SSL_SERVER_I_DN:   (none)
SSL_SERVER_I_O:   (none)
SSL_SERVER_I_OU:   (none)
SSL_SERVER_I_ST:   (none)
SSL_SERVER_O:   (none)
SSL_SERVER_OU:   (none)
SSL_SERVER_ST:   (none)
SSL_SSLEAY_VERSION:   (none)
USER_NAME:   user#31767

For more information, see http://www.apache.org/docs/mod/mod_include.html