Substitute Strings in Files with Ruby

Uses a list of regular expressions and replacement strings to make changes in text files.

Put in file "edit-all.rb" and run with

ruby edit-all.rb *.txt

Now accepts the target and the replacement from the command line or from the keyboard.

	## Make substitutions in a slew of files.
	## Backups having the extension ".bak" are made.
	## To make it descend into all subdirectories:
	## ruby edit-all.rb **/*.txt
	##
	## You may include the target & replacement on the
	## command line by using the -x switch:
	## ruby edit-all.rb -x 'original' 'replacement' *.txt
	# Only files below the current level?
	only_deep = false
	pairs = [
	# /Original text\./, "Edited in place.",
	# /(\w+) text\./, '\1 nonsense.'
	]
	if '-x' == ARGV.first
	ARGV.shift
	pairs = [ Regexp.new( ARGV.shift ), ARGV.shift ]
	end
	if pairs.size == 0
	puts "\nIn the replacement text, use \\1 for the first"
	puts "capture, \\2 for the second, etc.\n\n"
	loop {
	print "regular expression: "
	s = STDIN.gets.chomp
	break if s == ""
	pairs << Regexp.new( s )
	print "replacement: "
	pairs << STDIN.gets.chomp
	}
	end
	raise "\npairs must contain even number of items." if
	1 == pairs.size % 2
	ARGV.reject! { |f| File.directory?(f) }
	ARGV.reject! { |f| f !~ /\// } if only_deep
	if ARGV.empty?
	puts "I have no filenames."
	exit
	end
	# Turn on in-place editing. If you're certain that
	# nothing can go wrong, you may want to turn off
	# creation of backups by changing ".bak" to "" (won't
	# work under windoze).
	$-i = ".bak"
	ARGF.each{ |line|
	(0 ... pairs.size).step(2) { |i|
	line.gsub!( pairs[i], pairs[i+1] )
	}
	puts line
	}

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