What is a regex to match a string NOT at the end of a line?

Question

The regex /abc$/ will match an abc that does appear at the end of the line. How do I do the inverse?

I want to match abc that

Answer 1

/abc(?!$)/

(?!$) is a negative lookahead. It will look for any match of abc that is not directly followed by a $ (end of line)

Tested against

• abcddee (match)
• ffffdeeeabc (no match)
• adfassdfabcs (match)
• fabcddee (match)

applying it to your case:

ruby-1.9.2-p290 :007 > "aslkdjfabcalskdfjaabcaabc".gsub(/abc(?!$)/, 'xyz')
  => "aslkdjfxyzalskdfjaxyzaabc"