nobody the user apache is running as? this is fairly common,
nobody are all fairly common. try
ps ax | grep apache and see what shows up in the first row, and double check your configuration.
nobody is the user apache is running as, then you will want to do
sudo chown nobody.nobody /var/www/whatever/directory/ to change the ownership of the directory that apache needs rwx permissions to to
then apache will be able to create files in that directory, and the subsequent scripts will be able to download/install their plugins, etc into the directory as well.
then, as i said before, you will manage the plugins and scripts, etc from the web interface, NOT from the shell.
in your apache httpd configuration file, there is a line that says
User username where username is the name of whatever user apache httpd is run as on your system. your configuration file is potentially located at
/etc/apache2/apache2.conf but it could be different, especially if you're running an older (1.x) version of apache's httpd.