I don’t usually talk must about one-liners, but here’s one I used today.

ARGF and inject ... Two Great Tastes that Taste Great Together

Consider the following ruby one-lineer

ruby -e 'p ARGF.inject(0) { |sum, line| line.split[1].to_i + sum }'

Breaking it down, it …

• Iterates over each line of standard input (ARGF.inject(0))
• Splits the line into colums (line.split)
• Selects the second column ([1])
• Converts the second column to an integer (.to_i)
• Adds to to the running subtotal (+ sum)
• And prints the final sum (p)

In short, it sums up the numbers in the second column of a text file.

Cool. Now combine it with another one-liner …

lynx -dump http://gems.rubyforge.org/stats.html \
  | ruby -e 'p ARGF.inject(0) { |s,t| t.split[1].to_i + s }'

And you get the result …

1005821

... which is the number of gems served by RubyForge to date.

Over 1 million gems served :)