Sometimes you must use a mixture of Linux guides in order to get memcache working for you. If you need memchache to use Puelia, which is a PHP implementation of the Linked Data API, then you will need to know the commands for installing memcache on Ubuntu 10.04.
These are the commands you must enter: sudo apt-get install memcached, sudo apt-get install php-pear, sudo apt-get install php5-dev, sudo apt-get install libmemcached-dev, sudo pecl install Memcache, sudo echo "extension=memcache.so"> /etc/php5/apache2/conf.d/memcache.ini. Find your php.ini file, which is likely in /etc/php5/apache2/php.ini, and add this line to the bottom of the file: memcache.hash_strategy="consistent". Then try : memcached -d -m 1024 -1 127.0.0.1 -p 11211. If you get a message "can't run as root without -u switch" then try: memcached -d -u www-data -m 1024 -1 127.0.0.1 -p 11211, then: service apache2 restart.