see https://github.com/reddit/reddit/wiki/reddit-install-script-for-Ubuntu

install-reddit.sh

#!/bin/bash -e
# Neil Williams, reddit

# Configuration
REDDITUSER=reddit
REDDITHOME=/home/reddit
GITREPO=git://github.com/reddit/reddit.git
APTITUDE_OPTIONS="-y" # limit bandwidth: -o Acquire::http::Dl-Limit=100"

# make sure we're running as root 
if [ $(id -u) -ne 0 ]; then
    echo "This script must be run as root."
    exit 1
fi

# die if an error occurs
set -e

# make sure any installations we do aren't gonna need to be updated immediately
aptitude update

# add some external ppas for packages
DEBIAN_FRONTEND=noninteractive aptitude install $APTITUDE_OPTIONS python-software-properties
apt-add-repository ppa:cassandra-ubuntu/stable # for lucid 
apt-add-repository ppa:jason-alioth/reddit

# grab the new ppas' package listings
aptitude update

# install prerequisites
DEBIAN_FRONTEND=noninteractive aptitude install $APTITUDE_OPTIONS g++ python-dev python-setuptools python-profiler python-imaging cython git-core subversion libpng12-dev libjpeg62-dev libfreetype6-dev libxml2-dev libxslt1-dev gettext memcached postgresql postgresql-client libpq-dev libpqxx-dev libssl-dev curl daemontools daemontools-run rabbitmq-server haproxy libmemcached5 libmemcached-dev cassandra optipng

# disable init scripts for cassandra/memcached so we can control them in 
# daemontools
/etc/init.d/cassandra stop
update-rc.d -f cassandra remove

/etc/init.d/memcached stop
update-rc.d -f memcached remove 

# link the /service directory to debian's /etc/service 
if [ ! -L /service ]; then
    ln -s /etc/service /service
fi

# add the reddit user if not already present 
# note: the user will have a password of 'password'
if ! egrep "^$REDDITUSER:" /etc/passwd > /dev/null; then
    useradd -m -p TGya1gjhpZi82 $REDDITUSER
fi

# grab the source
cd $REDDITHOME

if [ ! -d $REDDITHOME/reddit ]; then
    sudo -u $REDDITUSER git clone $GITREPO
fi

# set up cassandra directories and configuration 
CASSANDRADIRS="/cassandra/commitlog /cassandra/data /cassandra/saved_caches"
CASSANDRAFILE=/etc/cassandra/cassandra.yaml
mkdir -p $CASSANDRADIRS 

chown -R reddit:reddit /cassandra
chmod 755 /cassandra
chmod 700 $CASSANDRADIRS 

if [ -L $CASSANDRAFILE ]; then 
    rm $CASSANDRAFILE 
fi

if [ -f $CASSANDRAFILE ]; then
    mv $CASSANDRAFILE /etc/cassandra/cassandra.orig.yaml
fi

ln -s $REDDITHOME/reddit/config/cassandra/cassandra.yaml $CASSANDRAFILE

# control cassandra with daemontools
ln -s $REDDITHOME/reddit/srv/cassandra /service/ || true

# start daemontools
/sbin/stop svscan || true
/sbin/start svscan
sleep 30 # give cassandra time to boot

# create the reddit keyspace and permacache CF
cat <<COMMANDS | cassandra-cli -B
connect localhost/9160;
create keyspace reddit with replication_factor = 1;
use reddit;
create column family permacache with column_type = 'Standard' and comparator = 'BytesType';
COMMANDS

# fix a weird directory expectation issue
if [ ! -L /usr/include/libxml ]; then
    ln -s /usr/include/libxml2/libxml /usr/include/libxml
fi  

ldconfig

# set up postgres
IS_DATABASE_CREATED=$(sudo -u postgres psql -t -c "SELECT COUNT(1) FROM pg_catalog.pg_database WHERE datname = 'reddit';")

if [ $IS_DATABASE_CREATED -ne 1 ]; then 
    cat <<PGSCRIPT | sudo -u postgres psql 
CREATE DATABASE reddit WITH ENCODING = 'utf8';
CREATE USER reddit WITH PASSWORD 'password';
PGSCRIPT
fi

sudo -u postgres psql reddit < /home/reddit/reddit/sql/functions.sql

# set up rabbitmq
if ! rabbitmqctl list_vhosts | egrep "^/$"
then
    rabbitmqctl add_vhost / 
fi

if ! rabbitmqctl list_users | egrep "^reddit$" 
then
    rabbitmqctl add_user reddit reddit
fi

rabbitmqctl set_permissions -p / reddit ".*" ".*" ".*" 

# run the setup script
cd $REDDITHOME/reddit/r2
sudo python setup.py develop

# downgrade some packages
easy_install "webhelpers==0.6.4"
easy_install "Paste==1.7.2-reddit-0.2"

# install the rest of the runscripts
cd $REDDITHOME

if [ ! -L $REDDITHOME/srv ]; then
    sudo -u reddit ln -s reddit/srv
fi

cd reddit/r2
if [ ! -L run.ini ]; then
    sudo -u reddit ln -s example.ini run.ini
fi

ln -s $REDDITHOME/reddit/srv/* /service/ || true

# run make
cd $REDDITHOME/reddit/r2
make


# install the crontab
CRONTAB=$(mktemp)

crontab -u reddit -l > $CRONTAB || true

cat >>$CRONTAB <<CRON
# m h  dom mon dow   command
*/5   *   *   *   *    ~/reddit/scripts/rising.sh
*/4   *   *   *   *    ~/reddit/scripts/send_mail.sh
*/3   *   *   *   *    ~/reddit/scripts/broken_things.sh
1     *   *   *   *    ~/reddit/scripts/update_promos.sh
0    23   *   *   *    ~/reddit/scripts/update_reddits.sh
CRON
crontab -u reddit $CRONTAB
rm $CRONTAB

# done!
cd $REDDITHOME
echo "Done installing reddit!"