script to delete one line from a file, uses input like this: ~/.ssh/known_hosts:60

delete_line.rb

#!/usr/bin/env ruby

# script to delete one line from a file
# because remembering how sed works is too hard
# Tijn Schuurmans - May 4, 2012

def print_usage
  puts <<-end_usage_description
delete_line

  delete one line from a file

  Usage:
    delete_line FILE:NUMBER

  Example:
    delete_line ~/.ssh/known_hosts:60
  end_usage_description
end

if ARGV.empty?
  print_usage
  exit
end

filename, line_number = ARGV.last.split(':')

raise "No such file #{filename}" unless File.file?(filename)
raise "I need a line number" if line_number.nil? || line_number.empty?


`sed -i '#{line_number} d' #{filename}`