How Many Gigs of RAM Are On My Server?

How much memory is on my linux server? Run the free command

free -g
 total       used       free     shared    buffers     cached
Mem:             2          1          0          0          0          1
-/+ buffers/cache:          0          1
Swap:            3          0          3

Which will tell you memory in Gigs. You can pass other flags, such as, -m or -k, which will give you the number in megs and kilobytes respectively.

The man page is as follows

man free

FREE(1)                                                                       Linux User's Manual                                                                      FREE(1)

NAME
       free - Display amount of free and used memory in the system

SYNOPSIS
       free [-b | -k | -m | -g] [-o] [-s delay ] [-t] [-V]

DESCRIPTION
       free  displays the total amount of free and used physical and swap memory in the system, as well as the buffers used by the kernel.  The shared memory column should be
       ignored; it is obsolete.

   Options
       The -b switch displays the amount of memory in bytes; the -k switch (set by default) displays it in kilobytes; the -m switch displays it in megabytes;  the  -g  switch
       displays it in gigabytes.

       The -t switch displays a line containing the totals.

       The  -o  switch  disables the display of a "buffer adjusted" line.  If the -o option is not specified, free subtracts buffer memory from the used memory and adds it to
       the free memory reported.

       The -s switch activates continuous polling delay seconds apart. You may actually specify any floating point number for delay, usleep(3) is used for microsecond resolu-
       tion delay times.

       The -V displays version information.

FILES
       /proc/meminfo
              memory information

SEE ALSO
       ps(1), slabtop(1), vmstat(8), top(1)

Have Git Email Committers After Pushes

You need a Mail Transfer Agent MTA on the server. The easiest way is to install Sendmail, which Git uses by default.

apt-get install sendmail

Remember that /etc/hosts file needs the ip address to map to the domain name your sending mail from

# vim /etc/hosts
127.0.0.1     localhost localhost.localdomain
207.136.202.87    wwwexample.com
 

Sendmail has a tendency to hang when sending mail otherwise. To test sendmail

sendmail email@example.com
this is a test
how are you today world?
.

The period on a line by itself denotes end of message and will terminate the prompt and deliver the message.

Now you need to configure Git to send email after it receives a “push” from a committer. You can add email addresses, or you can set up a mailing list to email all members. Either way, you accomplish this with the following command, just remember to cd into the git repository.

git config --add hooks.mailinglist "mailinglist@example.com"

Next you need to activate the post-receive hook, located in the hooks directory of your repository.

cp post-receive.sample post-receive

And uncomment the last line, which uses sendmail to deliver the commit message

# uncomment the last line but keep the period "."
. /usr/share/doc/git-core/contrib/hooks/post-receive-email

All done. Now just make some changes to your source code, add and commit them and you should receive an email with all the details!

Setting Up Users, Permissions and Groups for SSH Access to a Shared Git Repository

If you are having permission problems using git, such as

error: insufficient permission for adding an object to repository database ./objects

There are a couple thing you can do to remedy the situation, before moving to a full on git server like gitosis.

Create your users and add them to a group. Create (if you haven’t already) your git repo on the server and change permission and ownship and set the git config sharedRepository to true.

Here are all the commands, quick and dirty!

adduser sean
adduser jackson
groupadd developers
adduser sean developers
adduser jackson developers

mkdir -p /git/dev/app.git
cd /git/dev/app.git
git --bare init
vim description  #edit this file (mac os x complains otherwise)
chmod -R g+ws *
chgrp -R developers *
git repo-config core.sharedRepository true

Found from: http://mapopa.blogspot.com/2009/10/git-insufficient-permission-for-adding.html

Installing and Using Rvm on Mac OS X, Creating Gemsets and Reverting to Original Environment

What is RVM and why should you use it? RVM is a Ruby interpreter, version management tool. In short, it enables you to switch between different versions and releases of Ruby (for instance, version 1.8.6, 1.8.7, jruby 1.9.2, ruby enterprise edition) on the same machine, while associating different gems with each version of the ruby interpreter. This is super useful and awesome. If you want to play with Rails 3 and Ruby 1.9.1, for 5 minutes, and then want to switch back to your production apps, which are running on Rails 2.3.5 and Ruby 1.8.7, you can do so with a single command from the terminal. With RVM this is a fairly simple process so there is no reason not to install it. You can also revert back to your system settings (not using RVM) with a single command. After all Rails is just a gem, so you can easily create and manage different RVM “gemsets”, (sets of different gems), for the different versions of Ruby (rubies as RVM refers to them) you have installed.

Installing RVM

bash < <(curl -s https://rvm.beginrescueend.com/install/rvm)

Next you have to add rvm to your bash profile

# place in ~/.bash_profile as the very last line
[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm"

To check everything went well

type rvm | head -n1

Should tell you “rvm is a function”

How to add ruby, pass it the version to install

rvm install 1.8.7

*The current terminal session will load this environment. New sessions will not. To use a version of ruby and set it as the default, pass it the –default option

rvm use 1.8.7 --default

Next create a gemset, which will make available different gems for different versions

rvm gemset create rails_2_3_5

When you run “gem list”, you should see nothing!

gem install rails -v=2.3.5

Set a default rvm and default gemset, specify which gemset with the @ sign and include the –default option

rvm use 1.8.7@rails_2_3_5 --default

which gem
gem list
ruby --version
rails --version

And to get back to where you started and revert to using your original ruby setup

rvm system

For upgrading your version of RVM check out this post I wrote http://seanbehan.com/ruby/how-to-upgrade-rvm-on-mac-os-x/

Finally, you can create a .rvmrc file and put it in any directory and when you cd into that directory the environment specified in the file will be loaded automatically. This way you don’t have to remember the version and gemsets and type them into the console. All you have to do is put the ruby version and gemset name in the file like so

ruby1.8.7@rails2.3.5

You’ll be prompted to trust the .rvmrc file the first time, type “y” for yes. Also, subdirectories will inherit this .rvmrc so you can just put it in the parent directory like

rails2/
     .rvmrc
     app1
     app2
rails3/
     .rvmrc
     app1
     app2

And both app1 and app2 will use the .rvmrc environment while your rails3 directory apps will load the environment in its directory!

More information available here:
http://rvm.beginrescueend.com/rvm/install/
http://www.stjhimy.com/posts/4
http://eddorre.com/posts/installing-rails-3-beta-4-using-rvm

Renaming Routes in Rails 3 with :As and :Controller

Renaming routes in Rails 2.* is straight forward. It goes something like this.

## config/routes.rb
map.resources :users, :as => :members

This will give you users_path and form_for(User.new) helpers, for instance, mapping the url to /members instead of /users while using the users_controller.rb class.

In Rails 3.*, this is still possible. It is accomplished differently. In my opinion, it seems a little less elegant.

# config/routes.rb
resources :members, :as => :users, :controller => :users
# app/views/**/*.erb
link_to "Members", users_path
form_for User.new do |f|
# Rake routes
       users GET    /members(.:format)           {:controller=>"users", :action=>"index"}
       users POST   /members(.:format)           {:controller=>"users", :action=>"create"}
    new_user GET    /members/new(.:format)       {:controller=>"users", :action=>"new"}
   edit_user GET    /members/:id/edit(.:format)  {:controller=>"users", :action=>"edit"}
        user GET    /members/:id(.:format)       {:controller=>"users", :action=>"show"}
        user PUT    /members/:id(.:format)       {:controller=>"users", :action=>"update"}
        user DELETE /members/:id(.:format)       {:controller=>"users", :action=>"destroy"}

Your resource is “members” and you are overriding the name (using :as=>”users”) however, you still have to specify the controller.

http://pastie.org/1154956

Combat Spam with the Akismet Class for Ruby

Here is the Akismet.rb class, written by David Czarnecki. I’ve seen several tutorials online using this class, however, the class isn’t available at David’s blog. So… I reposted it here and at the pastie link below
http://pastie.org/1150693

Running Gem Server to View Docs for Ruby Libraries on Localhost

gem server

will boot up documentation on port 8808 by default pass it the -p flag followed by the port number to change.

gem server -p3000

Uploading Files with Curl

curl -i -F name=test -F filedata=@localfile.jpg http://example.org/upload

Courtesy of http://ariejan.net/2010/06/07/uploading-files-with-curl/

Using to_sentence method on an Array in Ruby on Rails

Member.all.collect {|member| member.firstname}.to_sentence
=> "Alex, Andy, and Sean"

Declare separator and the connector

Member.all.collect {|member| member.firstname}.to_sentence(
  :connector => "and last but not least,",
  :skip_last_comma => true
)
=> "Alex, Andy and last but not least, Sean"