Unable to run Mongo shell (Mac) - mongodb

Question

I'm new to web development and I wanted to get started with some RoR (using Locomotive CMS).
One of the things Locomotive asks for is to have Mongodb. I installed using homebrew by following this link http://docs.mongodb.org/manual/tutorial/install-mongodb-on-os-x/
It installs fine but then im not able to run it!
When I type 'mongo' on terminal I get the following output :
"MongoDB shell version: 2.4.3
connecting to: test
Mon May 6 11:12:28.927
JavaScript execution failed:
Error: couldn't connect to server
127.0.0.1:27017 at src/mongo/shell/mongo.js:L112
exception: connect failed"
BACKGROUND TO HELP DEBUGGING ( on Terminal) :
1.When I type in mongod I get the following :
"all output going to: /usr/local/var/log/mongodb/mongo.log"
Ownership of mongo.log :
-rw-r--r-- 1 username admin 22133 May 6 11:13 mongo.log
2.When I input mongod --fork I get the following :
about to fork child process, waiting until server is ready for connections.
forked process: 77566
all output going to: /usr/local/var/log/mongodb/mongo.log
ERROR: child process failed, exited with error number 100
3.Typing mongod --help gives the following warning:
* WARNING: soft rlimits too low. Number of files is 256, should be at least 1000
4.I have a folder called data (which acts as amongodb database, is this where it should be?)in root (PATH : /data) Ownership of data folder :
"drwxr-xr-x 3 username wheel 102 Apr 23 21:38 data"
5.Checking if ports are free: lsof -i :27017. Ive also tried to check for a running mongo process using activity montior and found zilch!
No output
6.Ive also tried : mongo --repair. Dint help!
Ive been stuk on this for a while, I've looked at most responses on stackoverflow and searched around to find a solution to this but nothing has helped so far!
UPDATE:
When I tried to start the mongo shell, I was getting the following l
log message from mongo.log:
5/6/13 1:33:27.616 PM com.apple.launchd:
(org.mongodb.mongod[79133])
open("/private/var/log/mongodb/output.log", ...): Permission denied
So I did a chmod777 for the particular folder and the shell launches!
Although I still get a warning when it launches as:
Server has startup warnings:
Mon May 6 13:33:27.693 [initandlisten]
Mon May 6 13:33:27.693 [initandlisten]
** WARNING: soft rlimits too low.
Number of files is 256, should be at least 1000
Any idea how I can silence these warnings?

Answer 1

To get the information you need to determine the cause of failure you need to look in (and post for us) the output from /usr/local/var/log/mongodb/mongo.log when it is trying to start.
However, the most common reason for the failure is the lack of the default database path - at /data/db. Either create that folder (and don't forget to make sure your user has permission to read/write to it) or specify a different path with the --dbpath option.
UPDATE: as you have since found, bad permissions on the log file can cause the issue, in a similar way to bad permissions on the data path.
In terms of the warning, the information you need is here:
https://superuser.com/questions/433746/is-there-a-fix-for-the-too-many-open-files-in-system-error-on-os-x-10-7-1
It is just that though, a warning - you can run MongoDB without an issue with those limits as long as it is not under heavy load. So, if this is a development environment, unless you plan on load testing, you should be fine