gistfile1.rb

schema_path = [0, 1, 2].map do |n|
  File.join("prod-backup", "schemas", (Time.current - n.days).strftime("%Y_%m_%d"))
end.select do |filepath| 
  File.exist? File.join(File::SEPARATOR, "Volumes", filepath) 
end.first || "file not found"

# changed to:

n = 0; schema_path = "file not found"; 
while n < 3 && schema_path == "file not found" do
  filepath = File.join("prod-backup", "schemas", (Time.current - n.days).strftime("%Y_%m_%d"))
  schema_path = filepath if File.exist? File.join(File::SEPARATOR, "Volumes", filepath) 
  n += 1
end