Cat A File With Line Numbers

You can quickly view a file using cat

$ cat Gemfile
source 'https://rubygems.org'


# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.2.0'
# Use postgresql as the database for Active Record
gem 'pg'

With the -n flag you can view that file with line numbers

$ cat -n Gemfile
 1  source 'https://rubygems.org'
 2  
 3  
 4  # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 5  gem 'rails', '4.2.0'
 6  # Use postgresql as the database for Active Record
 7  gem 'pg'