Viewing Files in Your CGI Directory
If you should find yourself wanting to monitor a log file
or database in your CGI directory, yet don't want to
download the file every time just to view it, this article
contains an answer.
This can also be a solution in situations where you have a
client who can't use FTP yet wants to view data files in
the CGI directory.
On most servers, only CGI scripts may be accessed in the
CGI directory. Other files are forbidden to browsers. This
ten-line Perl program, however, will display any plain text
file in the CGI directory (including Perl CGI programs):
#!/usr/bin/perl
use strict;
my $File = 'data.txt';
print "Content-Type: text/html\n\n<html><body><pre>";
open R,"<$File";
my $p = join '',<R>;
close R;
$p =~ s/\</\<\;/g;
$p =~ s/\>/\>\;/g;
print "$p</pre></body></html>";
Ensure the first line points to Perl on your server and the
third line specifies the file you want to view. If the file
is in a directory other than where the program is installed,
the directory path must also be specified.
Name the script whatever you want, so long as it has the
file extension your server expects for CGI programs. Upload
the script, set permissions to 0755, and type the script's
URL into your browser. Example:
http://domain.com/cgi-bin/script.cgi
Bookmark the URL and you can use your browser to view the
file whenever you desire.
Admittedly, the above program is limited in that it will
display only one specific file. It is, however, secure. If
anyone should happen upon your URL, the only file they can
view is the one the script will display.
If you have only a few files for display in your browser,
you may wish to upload a copy of the above program for each
file (just change the third line of the scripts). However,
if you have numerous files for display or would rather have
a more sophisticated program, you'll find a solution below.
Because the next program will display files that you name
in the program's URL, two security issues are addressed:
- A password is required to view a file. When a file
is requested, the password must be sent with the
request. The page is displayed only if the sent
password matches the password specified in the
script. Without this feature, anyone having
the URL to your script could view any file
in your CGI directory.
- Only files in the directory and sub-directories
where the program is installed may be viewed.
If the URL to your script is obtained and your
password found out, this feature prevents viewing
files in other locations, some of which might
contain sensitive information.
Here is the script:
#!/usr/bin/perl
use strict;
my $Password = 'myPW';
my($PW,$File) = split /\=/,$ENV{QUERY_STRING},2;
print "Content-Type: text/html\n\n<html><body>\n";
if($File) { &PrintFile; }
else { &PrintInstructions; }
print '</body></html>';
sub PrintFile
{
unless($PW eq $Password)
{
print '<h4>Boo!</h4>';
&PrintInstructions;
return;
}
my $currentdir = $ENV{SCRIPT_FILENAME};
$currentdir =~ s!^(.*)/.*?$!$1!;
if($currentdir =~ /\w/) { $currentdir .= '/'; }
else { $currentdir = ''; }
$File =~ s!^[./]+!!;
$File = "$currentdir$File";
unless(open R,"<$File")
{
print "<h4>Couldn't open file $File</h4>";
&PrintInstructions;
return;
}
my $p = join '',<R>;
close R;
$p =~ s/\</\<\;/g;
$p =~ s/\>/\>\;/g;
print "<pre>$p</pre>\n";
} # sub PrintFile
sub PrintInstructions
{
print <<END_OF_INSTRUCTIONS;
<center><h3>I N S T R U C T I O N S</h3></center>
<p>Type the URL of the script into your browser,
followed by ?PASSWORD=FILENAME</p>
<p>Replace PASSWORD with the password you specified
in the script. Replace FILENAME with the file name
of the file you want to view. If the file is in a
directory other than where the script resides, the
file name must include the directory path relative
to the script.</p>
<p>For example, if your password was "myPW" and
your file was "data.txt," the URL would be:</p>
<pre>
http://domain.com/cgi-bin/script.cgi?myPW=data.txt
</pre>
END_OF_INSTRUCTIONS
} # sub PrintInstructions
# END OF SCRIPT
Ensure the first line points to Perl on your server and the
third line specifies your password.
Give the script any acceptable file name and upload it. Set
permissions to 0755. Then type the program's URL into your
browser.
The program will present instructions.
There you have it, a nice little utility that can be
invaluable in certain situations. You may want to save
this article or remember WillMaster.com as the source
for this and many other programs.
Question:
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Will Bontrager
©2001 Bontrager Connection, LLC
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