How do I configure Apache 2 to run Perl CGI scripts?

Question

This post is intended to rescue the people who are suffering from *not being able to properly setup Apache2 for Perl on Ubuntu. (The system configurations specific to your Linux machine will be mentioned within square brackets, like [this]).

Possible outcome of an improperly setup Apache 2:

1. Browser trying to download the .pl file instead of executing and giving out the result.
2. Forbidden.
3. Internal server error.

If one follows the steps described below with a reasonable intelligence, he/she can get through the errors mentioned above.

Before starting the steps. Go to /etc/hosts file and add IP address / domain-name` for example:

127.0.0.1 www.BECK.com

Step 1: Install apache2 Step 2: Install mod_perl Step 3: Configure apache2

open sites-available/default and add the following,

<Files ~ "\.(pl|cgi)$">
    SetHandler perl-script
    PerlResponseHandler ModPerl::PerlRun
    Options +ExecCGI
    PerlSendHeader On
</Files>

<Directory />
    Options FollowSymLinks
    AllowOverride None
</Directory>
<Directory [path-to-store-your-website-files-like-.html-(perl-scripts-should-be-stored-in-cgi-bin] >
####(The Perl/CGI scripts can be stored out of the cgi-bin directory, but that's a story for another day. Let's concentrate on washing out the issue at hand)
####
    Options Indexes FollowSymLinks MultiViews
    AllowOverride None
    Order allow,deny
    allow from all
</Directory>

ScriptAlias /cgi-bin/ [path-where-you-want-your-.pl-and-.cgi-files]

<Directory [path-where-you-want-your-.pl-and-.cgi-files]>
    AllowOverride None
    Options ExecCGI -MultiViews +SymLinksIfOwnerMatch
    AddHandler cgi-script .pl
    Order allow,deny
    allow from all
</Directory>
<Files ~ "\.(pl|cgi)$">
    SetHandler perl-script
    PerlResponseHandler ModPerl::PerlRun
    Options +ExecCGI
    PerlSendHeader On
</Files>

<Directory />
    Options FollowSymLinks
    AllowOverride None
</Directory>
<Directory [path-to-store-your-website-files-like-.html-(perl-scripts-should-be-stored-in-cgi-bin] >
####(The Perl/CGI scripts can be stored out of the cgi-bin directory, but that's a story for another day. Let's concentrate on washing out the issue at hand)
####
    Options Indexes FollowSymLinks MultiViews
    AllowOverride None
    Order allow,deny
    allow from all
</Directory>

ScriptAlias /cgi-bin/ [path-where-you-want-your-.pl-and-.cgi-files]

<Directory [path-where-you-want-your-.pl-and-.cgi-files]>
    AllowOverride None
    Options ExecCGI -MultiViews +SymLinksIfOwnerMatch
    AddHandler cgi-script .pl
    Order allow,deny
    allow from all
</Directory>

Step 4:

Add the following lines to your /etc/apache2/apache2.conf file.

AddHandler cgi-script .cgi .pl
<Files ~ "\.pl$">
Options +ExecCGI
</Files>
<Files ~ "\.cgi$">
Options +ExecCGI
</Files>

<IfModule mod_perl.c>
<IfModule mod_alias.c>
Alias /perl/ /home/sly/host/perl/
</IfModule>
<Location /perl>
SetHandler perl-script
PerlHandler Apache::Registry
Options +ExecCGI
</Location>
</IfModule>

<Files ~ "\.pl$">
Options +ExecCGI
</Files>

Step 5:

Very important, or at least I guess so, only after doing this step, I got it to work.

AddHandler cgi-script .cgi .pl

<Files ~ "\.pl$">
Options +ExecCGI
</Files>
<Files ~ "\.cgi$">
Options +ExecCGI
</Files>

<IfModule mod_perl.c>
<IfModule mod_alias.c>
Alias /perl/ /home/sly/host/perl/
</IfModule>
<Location /perl>
SetHandler perl-script
PerlHandler Apache::Registry
Options +ExecCGI
</Location>
</IfModule>

<Files ~ "\.pl$">
Options +ExecCGI
</Files>

Step 6

Very important, or at least I guess so, only after doing this step, I got it to work.

Add the following to you /etc/apache2/sites-enabled/000-default file

<Files ~ "\.(pl|cgi)$">
SetHandler perl-script
PerlResponseHandler ModPerl::PerlRun
Options +ExecCGI
PerlSendHeader On
</Files>

Step 7:

Now add, your Perl script as test.pl in the place where you mentioned before in step 3 as [path-where-you-want-your-.pl-and-.cgi-files].

Give permissions to the .pl file using chmod and then, type the webaddress/cgi-bin/test.pl in the address bar of the browser, there you go, you got it.

(Now, many of the things would have been redundant in this post. Kindly ignore it.)

You'll need to take a look at your Apache error log to see what the "internal server error" is. The four most likely cases, in my experience would be:

1. The CGI program is in a directory which does not have CGI execution enabled. Solution: Add the ExecCGI option to that directory via either httpd.conf or a .htaccess file.

2. Apache is only configured to run CGIs from a dedicated cgi-bin directory. Solution: Move the CGI program there or add an AddHandler cgi-script .cgi statement to httpd.conf.

3. The CGI program is not set as executable. Solution (assuming a *nix-type operating system): chmod +x my_prog.cgi

4. The CGI program is exiting without sending headers. Solution: Run the program from the command line and verify that a) it actually runs rather than dying with a compile-time error and b) it generates the correct output, which should include, at the very minimum, a Content-Type header and a blank line following the last of its headers.

(Google search brought me to this question even though I did not ask for perl)

I had a problem with running scripts (albeit bash not perl). Apache had a config of ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/ however Apache error log showed File does not exist: /var/www/cgi-bin/test.html.

Tried putting the script in both /usr/lib/cgi-bin/ and /var/www/cgi-bin/ but neither were working.

After a prolonged googling session what cracked it for me was sudo a2enmod cgi and everything fell into place using /usr/lib/cgi-bin/.

If you have successfully installed Apache web server and Perl please follow the following steps to run cgi script using perl on ubuntu systems.

Before starting with CGI scripting it is necessary to configure apache server in such a way that it recognizes the CGI directory (where the cgi programs are saved) and allow for the execution of programs within that directory.

1. In Ubuntu cgi-bin directory usually resides in path /usr/lib , if not present create the cgi-bin directory using the following command.cgi-bin should be in this path itself.

    mkdir /usr/lib/cgi-bin
   

2. Issue the following command to check the permission status of the directory.

    ls -l /usr/lib | less
   

Check whether the permission looks as “drwxr-xr-x 2 root root 4096 2011-11-23 09:08 cgi- bin” if yes go to step 3.

If not issue the following command to ensure the appropriate permission for our cgi-bin directory.

     sudo chmod 755 /usr/lib/cgi-bin
     sudo chmod root.root /usr/lib/cgi-bin

3. Give execution permission to cgi-bin directory

    sudo chmod 755 /usr/lib/cgi-bin
   

Thus your cgi-bin directory is ready to go. This is where you put all your cgi scripts for execution. Our next step is configure apache to recognize cgi-bin directory and allow execution of all programs in it as cgi scripts.

Configuring Apache to run CGI script using perl

1. A directive need to be added in the configuration file of apache server so it knows the presence of CGI and the location of its directories. Initially go to location of configuration file of apache and open it with your favorite text editor

   cd /etc/apache2/sites-available/ 
   sudo gedit 000-default.conf
   

2. Copy the below content to the file 000-default.conf between the line of codes “DocumentRoot /var/www/html/” and “ErrorLog $ {APACHE_LOG_DIR}/error.log”

   ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
   <Directory "/usr/lib/cgi-bin">
   AllowOverride None
   Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
   Require all granted
   

3. Restart apache server with the following code

   sudo service apache2 restart
   

4. Now we need to enable cgi module which is present in newer versions of ubuntu by default

   sudo a2enmod cgi.load
   sudo a2enmod cgid.load
   

5. At this point we can reload the apache webserver so that it reads the configuration files again.

   sudo service apache2 reload
   

The configuration part of apache is over now let us check it with a sample cgi perl program.

Testing it out

1. Go to the cgi-bin directory and create a cgi file with extension .pl

   cd /usr/lib/cgi-bin/
   sudo gedit test.pl
   

2. Copy the following code on test.pl and save it.

   #!/usr/bin/perl -w
   print “Content-type: text/html\r\n\r\n”;
   print “CGI working perfectly!! \n”;
   

3. Now give the test.pl execution permission.

   sudo chmod 755 test.pl
   

4. Now open that file in your web browser http://Localhost/cgi-bin/test.pl

5. If you see the output “CGI working perfectly” you are ready to go.Now dump all your programs into the cgi-bin directory and start using them.

NB: Don't forget to give your new programs in cgi-bin, chmod 755 permissions so as to run it successfully without any internal server errors.

As of Ubuntu 12.04 (Precise Pangolin) (and perhaps a release or two before) simply installing apache2 and mod-perl via Synaptic and placing your CGI scripts in /usr/lib/cgi-bin is really all you need to do.

There are two ways to handle CGI scripts, SetHandler and AddHandler.

SetHandler cgi-script

applies to all files in a given context, no matter how they are named, even index.html or style.css.

AddHandler cgi-script .pl

is similar, but applies to files ending in .pl, in a given context. You may choose another extension or several, if you like.

Additionally, the CGI module must be loaded and Options +ExecCGI configured. To activate the module, issue

a2enmod cgi

and restart or reload Apache. Finally, the Perl CGI script must be executable. So the execute bits must be set

chmod a+x script.pl

and it should start with

#! /usr/bin/perl

as its first line.

---

When you use SetHandler or AddHandler (and Options +ExecCGI) outside of any directive, it is applied globally to all files. But you may restrict the context to a subset by enclosing these directives inside, e.g. Directory

<Directory /path/to/some/cgi-dir>
    SetHandler cgi-script
    Options +ExecCGI
</Directory>

Now SetHandler applies only to the files inside /path/to/some/cgi-dir instead of all files of the web site. Same is with AddHandler inside a Directory or Location directive, of course. It then applies to the files inside /path/to/some/cgi-dir, ending in .pl.