Ubuntu – Xampp: Access MySQL from terminal

Try to start mysql server through command line.

sudo service mysql start

or

sudo /etc/init.d/mysql start

As I can see in your question, you are using Apache 2.4.7, but your httpd.conf use Apache 2.2 directive.

According to Apache 2.4 manual:

Access control

In 2.2, access control based on client hostname, IP address, and other characteristics of client requests was done using the directives Order, Allow, Deny, and Satisfy.

In 2.4, such access control is done in the same way as other authorization checks, using the new module mod_authz_host. The old access control idioms should be replaced by the new authentication mechanisms, although for compatibility with old configurations, the new module mod_access_compat is provided.

Try this changes:

<Directory "/opt/lampp/apache2/htdocs">
    Options Indexes FollowSymLinks
    AllowOverride All
    Require all granted
</Directory> 

Allow and deny directive controls which hosts can or can't access an area of the server, Require tests whether an authenticated user is authorized according to a particular authorization provider and the specified restrictions. Require all granted means access is allowed unconditionally, let see Beyond just authorization

Update after reading configuration file:

Your default configuration file is right. The problem is wrong shebang in perl script.

Try this:

  #!/usr/bin/perl

Also:

  chmod +x /opt/lampp/cgi-bin/yourScript.pl

Here is a useful link about file permission problem

Second update

Change http content header:

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

This header is read by apache.

You apache is running as daemon user, check if each directory in script path are readable.