I am using a Ubuntu virtual machine.Where I installed OpenACS which depends upon AOLServer.To do so I had first shutdown Apache on this machine and then as per instructions given here

<http://openacs.org/xowiki/ubuntu>

Step 1) 
 aptitude install postgresql 

Step 2) 
 aptitude install openacs 

I had to shutdown Apache to do above installation.
Now the installation finishes.So I can access <http://localhost:8000>

but when ever I try to start Apache on this machine which was shutdown during installation I see the error 

```
 service apache2 start
  * Starting web server apache2 (98)Address already in use: make_sock: could not bind to address 0.0.0.0:80  no listening sockets available, shutting down
Unable to open logs

```

So I thought may be OpenACS installs AOLServer so Aolserver might be listening on port 80 I check 

```
 /etc/aolserver4/conf.d/openacs.sh 

```

and here

```
AOL_USER=www-data
AOL_GROUP=www-data
AOL_ADDRESS=192.168.1.15
AOL_PORT=8000
RUN_DAEMON=yes

```

So AOLServer is not listening on port 80 upto here it is confirmed.

```
  netstat -tualp  | grep 80
tcp  0      0 somemachine.somedimain.:8000 *:*   LISTEN   21321/aolserver4-ns

```

so netstat shows only 8000 in use.
Then why am I unable to start Apache in this case?

**Edit** 
as ooshro below pointed out
to check 
`netstat -tualp | grep \:www` the output  

I got was  

`tcp 0 0 localhost:www *:* LISTEN 2883/aolserver4-nsd`