Bulk validate YAML... in this case to track down a Jekyll error: "The value '{}' was passed to a date-related filter that expects valid dates in /_layouts/default.html or one of its layouts."

validate-yaml.rb

#!/usr/bin/env ruby

# 2021-09-19
# https://stackoverflow.com/questions/34150923/bulk-validating-yaml-files

require "yaml"

def check_file(filename)
  YAML.parse_file(filename)
  puts "OK"
  0
rescue Psych::SyntaxError => ex
  puts "Error#{ex.message[/: .+/]}"
  1
end

exit_code = 0
max_filename_length = ARGV.max_by(&:size).size

ARGV.each do |filename|
  printf "%-*s  ", max_filename_length, filename
  exit_code |= check_file(filename)
end

exit exit_code