Execute a command for each of the provided files, or to all files in the current directory

eachfile.rb

#!/usr/bin/env ruby
# eachfile.rb - Execute a command for each file
def help
  puts <<-HELP
Syntax: #{$0} [option] "COMMAND" File1 [File2] .. [FileN]
  The command is executed for each of the specified files.
  FILE in the command is substituted with the name of each file.
  If there is no FILE in command, the filename is given as parameter instead.
  When no files are provided, all files in the current directory are used.

The following optional options are not treated as a command:
  -h, --help: Show this help screen
  -V, --verbose: Be more verbose
HELP
end

def error(msg)
  help
  puts "Error: %s" % msg
  exit 1
end

class String
  def indent(depth=2)
    self.split("\n").map{|line| " "*depth + line}.join("\n") 
  end
end

raw_cmd = ARGV.shift.to_s
case raw_cmd
when '-V', '--verbose'
  @verbose = true
when '-h', '--help'
  help
  exit 0
else
  @no_options = true
end
raw_cmd = ARGV.shift.to_s unless @no_options

error("no command was provided") unless raw_cmd.size>0

files = ARGV
if files.size == 0
  files = Dir.glob('*').select {|f| File.file?(f)}
end

do_substitute = raw_cmd.grep('FILE').size>0
files.each do |file|
  if do_substitute
    cmd = raw_cmd.gsub('FILE',file)
  else
    cmd = raw_cmd + ' ' + file
  end
  puts "Execute: #{cmd}" if @verbose
  puts `#{cmd}`.indent(@verbose ? 2 : 0)
end