Perl error with $ENV variable

Shell Programming and Scripting
1

Hello my friends i have created a perl cgi script to see browser support for text and graphics but $ENV variable is not working ,

Code is:

#!/usr/bin/perl
#Author Ravinder kumar
# START

use warnings;
$nongraphic = 'lynx|CERN-Linemode|elinks';
$client = $ENV{'HTTP_USER_AGENT'};
$text = "text.html";
$graphics = "graphics.html";

if ($client =~ /$nongraphic/)
{
$htmldoc = $text;
}
else
{
$htmldoc = $graphics;
}
print "Content-type: text/html\n\n";
$docroot = $ENV{'DOCUMENT_ROOT'};
$htmldoc = join ("/",$docroot,$htmldoc);
if(open(HTML,"<",$htmldoc))
{
while (<HTML>)
{
print ;
}
close (HTML);
}
else
{
print "There is some problem\n"
}
exit (0);

#END

--------------------------------------------------------------

OUTPUT IS :

[root@cent6 cgi-bin]# ./support.pl
Use of uninitialized value $client in pattern match (m//) at ./support.pl line 11.
Content-type: text/html

Use of uninitialized value $docroot in join or string at ./support.pl line 21.

There is some problem
---------------------------------------------------------------
here u can see $ENV variable is not working

any help

2

BASH is not an HTTP user agent. :wink: HTTP_USER_AGENT is not going to be set when you run it from a commandline! That's a CGI thing.

For testing purposes, you can always set them manually, yourself:

HTTP_USER_AGENT="angrysnail-5.0" DOCUMENT_ROOT="/path/to/whatever" HTML="whateverfile" ./support.pl

Be very careful with this perl script, by the way. It could potentially be exploited to open arbitrary files, regardless of .htaccess limits.

3

hello Corona see this script is working by set %ENV variable

#!/usr/bin/perl

# Author Ravinder kumar
# Cgi script Second part

#Start
print "Content-type: text/html\n\n";

print "<table>";
foreach (sort keys %ENV)
{
  print "<tr><td>$_</td><td>$ENV{$_}</td></tr>\n";
}
print "</table>";

# END

is there any way to set %ENV so i can access individual element by $ENV variable in above script

mean by declaring %ENV variable.

4

What version of Perl are you using?

tyler_durden

5

Version is

This is perl, v5.10.1

6

In the output of this script (your 2nd script), what is the value of the key "HTTP_USER_AGENT" ?

tyler_durden

7

Output of second script :--------

   DOCUMENT_ROOT /var/www/html
   GATEWAY_INTERFACE CGI/1.1
   HTTP_ACCEPT text/html, text/plain, text/css, text/sgml, */*;q=0.01
   HTTP_ACCEPT_ENCODING gzip, bzip2
   HTTP_ACCEPT_LANGUAGE en
   HTTP_HOST localhost
   HTTP_USER_AGENT Lynx/2.8.6rel.5 libwww-FM/2.14 SSL-MM/1.4.1
   OpenSSL/1.0.0-fips
   PATH /sbin:/usr/sbin:/bin:/usr/bin
   QUERY_STRING
   REMOTE_ADDR ::1
   REMOTE_PORT 46329
   REQUEST_METHOD GET
   REQUEST_URI /cgi-bin/env.pl
   SCRIPT_FILENAME /var/www/cgi-bin/env.pl
   SCRIPT_NAME /cgi-bin/env.pl
   SERVER_ADDR ::1
   SERVER_ADMIN root@localhost
   SERVER_NAME localhost
   SERVER_PORT 80
   SERVER_PROTOCOL	HTTP/1.1
   SERVER_SIGNATURE	Apache Server at 192.168.3.15 Port 80
   SERVER_SOFTWARE	Apache
8

It will not do that when you run it by ./programname as you did above. BASH is not an HTTP user agent. You'll have to export the variables yourself.

9

Sorry Corona for this but u cannot understand, bash variable is different thing
that access by this perl module

use Env;

this is cgi variable which is stored in %ENV hash variable through which we can access $ENV variable

u can see the second script it is working script .

There is way to access $ENV variable by set %ENV hash globally

but i do not know how

---------- Post updated at 02:32 PM ---------- Previous update was at 01:30 PM ----------

:slight_smile: Finally the script has created successfully

Thanks for your help my friends , especialy corona sorry for above words

Working CODE ------

#!/usr/bin/perl
#Author Ravinder kumar
use warnings;
print "Content-type: text/html\n\n";

# Set $ENV variable here , to set another $ENV variable use different
# foreach loop, otherwise it will break up the script

foreach(sort keys %ENV)
{
$client = $ENV{'HTTP_USER_AGENT'};
}

# Variables

$nongraphic = 'Lynx|CERN-Linemode|ELinks';
$text = "text.html";
$graphics = "graphics.html";

# Support Checking

if ($client =~ /$nongraphic/)
{
$htmldoc = $text;
}
else
{
$htmldoc = $graphics;
}
$path = "/var/www/cgi-bin";
$htmldoc = join ("/",$path,$htmldoc);

# Result

if(open(HTML,"<",$htmldoc))
{
while (<HTML>)
{
print ;
}
close (HTML);
}
else
{
print "There is some problem\n"
}
exit (0);

#END
10

There is nothing magical or CGI-only about the $ENV variable. They are just environment variables. BASH can also set as I illustrated above, which is necessary when you wish to run it like ./programname as you did above.