ruby_tips.rb

# change file extension
input_file="./xxx.log"
output_file= "#{input_file.chomp(File.extname(input_file))}.csv"
puts "input_file is #{input_file}, output_file is #{output_file}"

# get first line of files
input_file="./xxx.log"
first_line = File.open(src_file, "r") {|f| f.readline}
puts "first_line of file[#{input_file}] is #{first_line}"