Installing and Running MongoDB on OSX

Assuming you have created the data/db directory under bin after install.

1. Start a terminal for your mongo server
2. Go to <mongodb-install-directory>/bin directory

3. Run the command

   ./mongod

4. Start a terminal for your mongo shell

5. Go to <mongodb-install-directory>/bin directory

6. Run the command (make sure you put the name of the database)

   ./mongo test

Problem here is you are trying to open a mongo shell without starting a mongo db which is listening to port 127.0.0.1:27017(deafault for mongo db) thats what the error is all about:

Error: couldn't connect to server 127.0.0.1:27017 at src/mongo/shell/mongo.js:145 exception: connect failed

The easiest solution is to open the terminal and type

$ mongod --dbpath ~/data/db

Note: dbpath here is "Users/user" where data/db directories are created

i.e., you need to create directory data and sub directory db in your user folder. For e.g say `

/Users/johnny/data

After mongo db is up. Open another terminal in new window and type

$ mongo

it will open mongo shell with your mongo db connection opened in another terminal.

Updated answer (9/2/2019):

Homebrew has removed mongodb formula from its core repository, see this pull request.

The new way to install mongodb using Homebrew is as follows:

~> brew tap mongodb/brew
~> brew install mongodb-community

After installation you can start the mongodb service by following the caveats:

~> brew info mongodb-community
mongodb/brew/mongodb-community: stable 4.2.0
High-performance, schema-free, document-oriented database
https://www.mongodb.com/
Not installed
From: https://github.com/mongodb/homebrew-brew/blob/master/Formula/mongodb-community.rb
==> Caveats
To have launchd start mongodb/brew/mongodb-community now and restart at login:
  brew services start mongodb/brew/mongodb-community
Or, if you don't want/need a background service you can just run:
  mongod --config /usr/local/etc/mongod.conf

Deprecated answer (8/27/2019):

I assume you are using Homebrew. You can see the additional information that you need using brew info $FORMULA

~> brew info mongo                                                           255
mongodb: stable 2.4.6, devel 2.5.1
http://www.mongodb.org/
/usr/local/Cellar/mongodb/2.4.5-x86_64 (20 files, 287M) *
  Built from source
From: https://github.com/mxcl/homebrew/commits/master/Library/Formula/mongodb.rb
==> Caveats
To reload mongodb after an upgrade:
    launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.mongodb.plist
    launchctl load ~/Library/LaunchAgents/homebrew.mxcl.mongodb.plist

Caveats is what you need to follow after installation.

If you have installed mongodb through homebrew then you can simply start mongodb through (mongodb-community if installted mongodb-community

brew services start mongodb

OR

brew services start mongodb-community

Then access the shell by

mongo

You can shut down your db by

brew services stop mongodb

You can restart your db by

brew services restart mongodb

For more options

brew info mongodb