What does a2ensite do apart from creating a symlink?

Question

I regularly use a2ensite and a2dissite to enable and disable sites in Apache. As far as I know it does little more than simply creating a symlink from /etc/apache2/sites-enabled to /etc/apache2/sites-available. I can also do it manually, but because it saves me typing a few characters I use these shortcuts.

I just did a cat /usr/sbin/a2ensite, and to my surprise it's quite an elaborate program. According to the man pages, it does little more than enabling sites though. I briefly looked over the (Perl) source code, but even though it's a lot of code I don't really understand what it does more than simply creating a symlink.

Why does it need so much code to simply create a symlink? What am I missing here?

Answer 1

Actually

• a2enconf
• a2disconf
• a2dismod
• a2ensite
• a2dissite

are all only symlinks to a2enmod:

$ /usr/sbin$ ll -d a2*
lrwxrwxrwx 1 root root       7 Jul 15 17:33 a2disconf -> a2enmod
lrwxrwxrwx 1 root root       7 Jul 15 17:33 a2dismod -> a2enmod
lrwxrwxrwx 1 root root       7 Jul 15 17:33 a2dissite -> a2enmod
lrwxrwxrwx 1 root root       7 Jul 15 17:33 a2enconf -> a2enmod
-rwxr-xr-x 1 root root   15424 Apr  5  2016 a2enmod
lrwxrwxrwx 1 root root       7 Jul 15 17:33 a2ensite -> a2enmod
-rwxr-xr-x 1 root root    9870 Jul 15 17:33 a2query

and a2enmod implements the functionality of all six of them in one script. It decides what to do depending on $0 (i.e. the name the script was called with).

That's probably the reason why it's more complicated than a simple ln -s.