RUBYのgsubでアポストロフィ[’]をエスケープ

ちょっと悩んだのでメモ

#!/bin/env ruby -Ku
s="MAC'D"
ss=s.gsub("'","\\\'")
print ss	# MACDD

#!/bin/env ruby -Ku

s="MAC'D"

ss=s.gsub("'","\\\'")

print ss # MACDD

#!/bin/env ruby -Ku
s="MAC'D"
ss=s.gsub("'","\\'")
print ss	# MACDD

#!/bin/env ruby -Ku

s="MAC'D"

ss=s.gsub("'","\\'")

print ss # MACDD

#!/bin/env ruby -Ku
s="MAC'D"
ss=s.gsub("'","\\\\'")
print ss	 # MAC\'D

#!/bin/env ruby -Ku

s="MAC'D"

ss=s.gsub("'","\\\\'")

print ss # MAC\'D