"s/every day/frequently/g” is a UNIX-y way of saying “substitute ‘frequently’ in place of ‘every day’ in the entire document”. (See http://en.wikipedia.org/wik

"s/every day/frequently/g” is a UNIX-y way of saying “substitute ‘frequently’ in place of ‘every day’ in the entire document”. (See http://en.wikipedia.org/wiki/Sed#Substitution http://en.wikipedia.org/wiki/Sed#Substitution .)