Append File

Opening a file in append mode adds text after the existing content.

append_file.rb

require "tmpdir"

extra_line = 

Dir.mktmpdir do |dir|
  path = File.join(dir, "log.txt")
  File.write(path, "first\nsecond\n")

  file = File.open(path, "a")
  file.puts extra_line
  file.close

  lines = File.read(path).split("\n")

  puts "file=#{File.basename(path)}"
  puts "lines=#{lines.join(",")}"
  puts "last=#{lines.last}"
end

require "tmpdir"

extra_line = 

Dir.mktmpdir do |dir|
  path = File.join(dir, "log.txt")
  File.write(path, "first\nsecond\n")

  file = File.open(path, "a")
  file.puts extra_line
  file.close

  lines = File.read(path).split("\n")

  puts "file=#{File.basename(path)}"
  puts "lines=#{lines.join(",")}"
  puts "last=#{lines.last}"
end

require "tmpdir"

extra_line = 

Dir.mktmpdir do |dir|
  path = File.join(dir, "log.txt")
  File.write(path, "first\nsecond\n")

  file = File.open(path, "a")
  file.puts extra_line
  file.close

  lines = File.read(path).split("\n")

  puts "file=#{File.basename(path)}"
  puts "lines=#{lines.join(",")}"
  puts "last=#{lines.last}"
end

append mode Append mode keeps existing file content and writes new content at the end.