press the escape key to exit from the edit mode

type :x! to save and exit

or type :q! to quit without saving

now we can use yum to install the mongodb server:

# yum install mongo-10gen mongo-10gen-server

the default location on centos6 is:

/etc/mongod.conf

configure mongodb conf:

# vi /etc/mongod.conf

# mongo.conf

#where to log
logpath=/var/log/mongo/mongod.log

logappend=true

# fork and run in background
fork = true

#port = 27017

dbpath=/var/lib/mongo

# location of pidfile
pidfilepath = /var/run/mongodb/mongod.pid

# Disables write-ahead journaling
# nojournal = true

# Enables periodic logging of CPU utilization and I/O wait
#cpu = true

# Turn on/off security.  Off is currently the default
#noauth = true
auth = true

# Verbose logging output.
#verbose = true

# Inspect all client data for validity on receipt (useful for
# developing drivers)
#objcheck = true

# Enable db quota management
#quota = true

# Set oplogging level where n is
#   0=off (default)
#   1=W
#   2=R
#   3=both
#   7=W+some reads
#diaglog = 0

# Ignore query hints
#nohints = true

# Disable the HTTP interface (Defaults to localhost:27018).
#nohttpinterface = true

# Turns off server-side scripting.  This will result in greatly limited
# functionality
#noscripting = true

# Turns off table scans.  Any query that would do a table scan fails.
#notablescan = true

# Disable data file preallocation.
#noprealloc = true

# Specify .ns file size for new databases.
# nssize = 

# Accout token for Mongo monitoring server.
#mms-token = 

# Server name for Mongo monitoring server.
#mms-name = 

# Ping interval for Mongo monitoring server.
#mms-interval = 

# Replication Options

# in replicated mongo databases, specify here whether this is a slave or master
#slave = true
#source = master.example.com
# Slave only: specify a single database to replicate
#only = master.example.com
# or
#master = true
#source = slave.example.com

the first option i did modify was the "port" option which i commented, because i have a dedicated server an will use the mongodb socket instead of the port, i don't need access from outside to that port either

#port = 27017

then next option that i changed is the "auth" option, i have set the authentification to true

auth = true

if you need more information about configuration options i recommend to read the mongodb configuration page

add chkconfig rule:

chkconfig --levels 235 mongod on

when you start mongo it creates a socket

/tmp/mongodb-27017.sock

if you get this error: "Error: couldn't connect to server" probably mongod is not started:

# service mongod start

now we have to install the php mongo (pecl) extension, this package contains the MongoDB database drivers used by php to communicate with MongoDB

# yum install php-pecl-mongo

no need to edit your php.ini and to add something like mongo.so to it, every package installed through yum will put an dot so file to a directory like /usr/lib64/php/modules/, php will look at that directory on startup and automatically load all the extensions so files that reside inside